diff --git a/Gulpfile.js b/Gulpfile.js
index 678cb173d7..04535b387b 100644
--- a/Gulpfile.js
+++ b/Gulpfile.js
@@ -21,32 +21,41 @@ function swapSrcWithLib(srcPath) {
 
 gulp.task("default", ["build"]);
 
-gulp.task("build", function () {
-  return gulp.src(scripts, { base: base })
-    .pipe(plumber({
-      errorHandler: function (err) {
-        gutil.log(err.stack);
-      },
-    }))
-    .pipe(newer({
-      dest: base,
-      map: swapSrcWithLib,
-    }))
-    .pipe(through.obj(function (file, enc, callback) {
-      gutil.log("Compiling", "'" + chalk.cyan(file.relative) + "'...");
-      callback(null, file);
-    }))
+gulp.task("build", function() {
+  return gulp
+    .src(scripts, { base: base })
+    .pipe(
+      plumber({
+        errorHandler: function(err) {
+          gutil.log(err.stack);
+        },
+      })
+    )
+    .pipe(
+      newer({
+        dest: base,
+        map: swapSrcWithLib,
+      })
+    )
+    .pipe(
+      through.obj(function(file, enc, callback) {
+        gutil.log("Compiling", "'" + chalk.cyan(file.relative) + "'...");
+        callback(null, file);
+      })
+    )
     .pipe(babel())
-    .pipe(through.obj(function (file, enc, callback) {
-      // Passing 'file.relative' because newer() above uses a relative path and this keeps it consistent.
-      file.path = path.resolve(file.base, swapSrcWithLib(file.relative));
-      callback(null, file);
-    }))
+    .pipe(
+      through.obj(function(file, enc, callback) {
+        // Passing 'file.relative' because newer() above uses a relative path and this keeps it consistent.
+        file.path = path.resolve(file.base, swapSrcWithLib(file.relative));
+        callback(null, file);
+      })
+    )
     .pipe(gulp.dest(base));
 });
 
-gulp.task("watch", ["build"], function () {
-  watch(scripts, { debounceDelay: 200 }, function () {
+gulp.task("watch", ["build"], function() {
+  watch(scripts, { debounceDelay: 200 }, function() {
     gulp.start("build");
   });
 });
diff --git a/packages/babel-cli/src/_babel-node.js b/packages/babel-cli/src/_babel-node.js
index 4b9ac5160a..56c03c7683 100644
--- a/packages/babel-cli/src/_babel-node.js
+++ b/packages/babel-cli/src/_babel-node.js
@@ -24,9 +24,21 @@ function collect(value, previousValue): Array<string> {
 /* eslint-disable max-len */
 program.option("-e, --eval [script]", "Evaluate script");
 program.option("-p, --print [code]", "Evaluate script and print result");
-program.option("-o, --only [globs]", "A comma-separated list of glob patterns to compile", collect);
-program.option("-i, --ignore [globs]", "A comma-separated list of glob patterns to skip compiling", collect);
-program.option("-x, --extensions [extensions]", "List of extensions to hook into [.es6,.js,.es,.jsx,.mjs]", collect);
+program.option(
+  "-o, --only [globs]",
+  "A comma-separated list of glob patterns to compile",
+  collect,
+);
+program.option(
+  "-i, --ignore [globs]",
+  "A comma-separated list of glob patterns to skip compiling",
+  collect,
+);
+program.option(
+  "-x, --extensions [extensions]",
+  "List of extensions to hook into [.es6,.js,.es,.jsx,.mjs]",
+  collect,
+);
 program.option("-w, --plugins [string]", "", collect);
 program.option("-b, --presets [string]", "", collect);
 /* eslint-enable max-len */
@@ -55,23 +67,28 @@ const replPlugin = ({ types: t }) => ({
 
     VariableDeclaration(path) {
       if (path.node.kind !== "var") {
-        throw path.buildCodeFrameError("Only `var` variables are supported in the REPL");
+        throw path.buildCodeFrameError(
+          "Only `var` variables are supported in the REPL",
+        );
       }
     },
 
     Program(path) {
-      if (path.get("body").some((child) => child.isExpressionStatement())) return;
+      if (path.get("body").some(child => child.isExpressionStatement())) return;
 
       // If the executed code doesn't evaluate to a value,
       // prevent implicit strict mode from printing 'use strict'.
-      path.pushContainer("body", t.expressionStatement(t.identifier("undefined")));
+      path.pushContainer(
+        "body",
+        t.expressionStatement(t.identifier("undefined")),
+      );
     },
   },
 });
 
 //
 
-const _eval = function (code, filename) {
+const _eval = function(code, filename) {
   code = code.trim();
   if (!code) return undefined;
 
@@ -113,7 +130,7 @@ if (program.eval || program.print) {
 
     let i = 0;
     let ignoreNext = false;
-    args.some(function (arg, i2) {
+    args.some(function(arg, i2) {
       if (ignoreNext) {
         ignoreNext = false;
         return;
@@ -133,7 +150,9 @@ if (program.eval || program.print) {
 
     // make the filename absolute
     const filename = args[0];
-    if (!path.isAbsolute(filename)) args[0] = path.join(process.cwd(), filename);
+    if (!path.isAbsolute(filename)) {
+      args[0] = path.join(process.cwd(), filename);
+    }
 
     // add back on node and concat the sliced args
     process.argv = ["node"].concat(args);
diff --git a/packages/babel-cli/src/babel-external-helpers.js b/packages/babel-cli/src/babel-external-helpers.js
index 6624b64d65..2180d10773 100755
--- a/packages/babel-cli/src/babel-external-helpers.js
+++ b/packages/babel-cli/src/babel-external-helpers.js
@@ -10,8 +10,16 @@ function collect(value, previousValue): Array<string> {
   return previousValue ? previousValue.concat(values) : values;
 }
 
-commander.option("-l, --whitelist [whitelist]", "Whitelist of helpers to ONLY include", collect);
-commander.option("-t, --output-type [type]", "Type of output (global|umd|var)", "global");
+commander.option(
+  "-l, --whitelist [whitelist]",
+  "Whitelist of helpers to ONLY include",
+  collect,
+);
+commander.option(
+  "-t, --output-type [type]",
+  "Type of output (global|umd|var)",
+  "global",
+);
 
 commander.usage("[options]");
 commander.parse(process.argv);
diff --git a/packages/babel-cli/src/babel-node.js b/packages/babel-cli/src/babel-node.js
index 101c422f0a..94682978f9 100755
--- a/packages/babel-cli/src/babel-node.js
+++ b/packages/babel-cli/src/babel-node.js
@@ -33,7 +33,7 @@ function getNormalizedV8Flag(arg) {
   return arg;
 }
 
-getV8Flags(function (err, v8Flags) {
+getV8Flags(function(err, v8Flags) {
   babelArgs.forEach(function(arg) {
     const flag = arg.split("=")[0];
 
@@ -59,7 +59,10 @@ getV8Flags(function (err, v8Flags) {
         break;
 
       default:
-        if (v8Flags.indexOf(getNormalizedV8Flag(flag)) >= 0 || arg.indexOf("--trace") === 0) {
+        if (
+          v8Flags.indexOf(getNormalizedV8Flag(flag)) >= 0 ||
+          arg.indexOf("--trace") === 0
+        ) {
           args.unshift(arg);
         } else {
           args.push(arg);
@@ -80,9 +83,11 @@ getV8Flags(function (err, v8Flags) {
     if (err.code !== "MODULE_NOT_FOUND") throw err;
 
     const child_process = require("child_process");
-    const proc = child_process.spawn(process.argv[0], args, { stdio: "inherit" });
-    proc.on("exit", function (code, signal) {
-      process.on("exit", function () {
+    const proc = child_process.spawn(process.argv[0], args, {
+      stdio: "inherit",
+    });
+    proc.on("exit", function(code, signal) {
+      process.on("exit", function() {
         if (signal) {
           process.kill(process.pid, signal);
         } else {
diff --git a/packages/babel-cli/src/babel/dir.js b/packages/babel-cli/src/babel/dir.js
index 1113fd9afc..d59e4e5844 100644
--- a/packages/babel-cli/src/babel/dir.js
+++ b/packages/babel-cli/src/babel/dir.js
@@ -6,19 +6,27 @@ import fs from "fs";
 
 import * as util from "./util";
 
-export default function (commander, filenames, opts) {
+export default function(commander, filenames, opts) {
   function write(src, relative) {
-    if (!util.isCompilableExtension(relative, commander.extensions)) return false;
+    if (!util.isCompilableExtension(relative, commander.extensions)) {
+      return false;
+    }
 
     // remove extension and then append back on .js
     relative = relative.replace(/\.(\w*?)$/, "") + ".js";
 
     const dest = path.join(commander.outDir, relative);
 
-    const data = util.compile(src, defaults({
-      sourceFileName: slash(path.relative(dest + "/..", src)),
-      sourceMapTarget: path.basename(relative),
-    }, opts));
+    const data = util.compile(
+      src,
+      defaults(
+        {
+          sourceFileName: slash(path.relative(dest + "/..", src)),
+          sourceMapTarget: path.basename(relative),
+        },
+        opts,
+      ),
+    );
 
     if (!data) return false;
 
@@ -55,7 +63,7 @@ export default function (commander, filenames, opts) {
     if (stat.isDirectory(filename)) {
       const dirname = filename;
 
-      util.readdir(dirname).forEach(function (filename) {
+      util.readdir(dirname).forEach(function(filename) {
         const src = path.join(dirname, filename);
         handleFile(src, filename);
       });
@@ -71,7 +79,7 @@ export default function (commander, filenames, opts) {
   if (commander.watch) {
     const chokidar = util.requireChokidar();
 
-    filenames.forEach(function (dirname) {
+    filenames.forEach(function(dirname) {
       const watcher = chokidar.watch(dirname, {
         persistent: true,
         ignoreInitial: true,
@@ -81,8 +89,8 @@ export default function (commander, filenames, opts) {
         },
       });
 
-      ["add", "change"].forEach(function (type) {
-        watcher.on(type, function (filename) {
+      ["add", "change"].forEach(function(type) {
+        watcher.on(type, function(filename) {
           const relative = path.relative(dirname, filename) || filename;
           try {
             handleFile(filename, relative);
diff --git a/packages/babel-cli/src/babel/file.js b/packages/babel-cli/src/babel/file.js
index 689f8f9353..79ceef3f6a 100644
--- a/packages/babel-cli/src/babel/file.js
+++ b/packages/babel-cli/src/babel/file.js
@@ -7,14 +7,14 @@ import fs from "fs";
 
 import * as util from "./util";
 
-export default function (commander, filenames, opts) {
+export default function(commander, filenames, opts) {
   if (commander.sourceMaps === "inline") {
     opts.sourceMaps = true;
   }
 
   let results = [];
 
-  const buildResult = function () {
+  const buildResult = function() {
     const map = new sourceMap.SourceMapGenerator({
       file: path.basename(commander.outFile || "") || "stdout",
       sourceRoot: opts.sourceRoot,
@@ -23,14 +23,14 @@ export default function (commander, filenames, opts) {
     let code = "";
     let offset = 0;
 
-    results.forEach(function (result) {
+    results.forEach(function(result) {
       code += result.code + "\n";
 
       if (result.map) {
         const consumer = new sourceMap.SourceMapConsumer(result.map);
         const sources = new Set();
 
-        consumer.eachMapping(function (mapping) {
+        consumer.eachMapping(function(mapping) {
           if (mapping.source != null) sources.add(mapping.source);
 
           map.addMapping({
@@ -39,14 +39,17 @@ export default function (commander, filenames, opts) {
               column: mapping.generatedColumn,
             },
             source: mapping.source,
-            original: mapping.source == null ? null : {
-              line: mapping.originalLine,
-              column: mapping.originalColumn,
-            },
+            original:
+              mapping.source == null
+                ? null
+                : {
+                    line: mapping.originalLine,
+                    column: mapping.originalColumn,
+                  },
           });
         });
 
-        sources.forEach((source) => {
+        sources.forEach(source => {
           const content = consumer.sourceContentFor(source, true);
           if (content !== null) {
             map.setSourceContent(source, content);
@@ -59,7 +62,10 @@ export default function (commander, filenames, opts) {
 
     // add the inline sourcemap comment if we've either explicitly asked for inline source
     // maps, or we've requested them without any output file
-    if (commander.sourceMaps === "inline" || (!commander.outFile && commander.sourceMaps)) {
+    if (
+      commander.sourceMaps === "inline" ||
+      (!commander.outFile && commander.sourceMaps)
+    ) {
       code += "\n" + convertSourceMap.fromObject(map).toComment();
     }
 
@@ -69,7 +75,7 @@ export default function (commander, filenames, opts) {
     };
   };
 
-  const output = function () {
+  const output = function() {
     const result = buildResult();
 
     if (commander.outFile) {
@@ -86,36 +92,45 @@ export default function (commander, filenames, opts) {
     }
   };
 
-  const stdin = function () {
+  const stdin = function() {
     let code = "";
 
     process.stdin.setEncoding("utf8");
 
-    process.stdin.on("readable", function () {
+    process.stdin.on("readable", function() {
       const chunk = process.stdin.read();
       if (chunk !== null) code += chunk;
     });
 
-    process.stdin.on("end", function () {
-      results.push(util.transform(commander.filename, code, defaults({
-        sourceFileName: "stdin",
-      }, opts)));
+    process.stdin.on("end", function() {
+      results.push(
+        util.transform(
+          commander.filename,
+          code,
+          defaults(
+            {
+              sourceFileName: "stdin",
+            },
+            opts,
+          ),
+        ),
+      );
       output();
     });
   };
 
-  const walk = function () {
+  const walk = function() {
     const _filenames = [];
     results = [];
 
-    filenames.forEach(function (filename) {
+    filenames.forEach(function(filename) {
       if (!fs.existsSync(filename)) return;
 
       const stat = fs.statSync(filename);
       if (stat.isDirectory()) {
         const dirname = filename;
 
-        util.readdirFilter(filename).forEach(function (filename) {
+        util.readdirFilter(filename).forEach(function(filename) {
           _filenames.push(path.join(dirname, filename));
         });
       } else {
@@ -123,16 +138,25 @@ export default function (commander, filenames, opts) {
       }
     });
 
-    _filenames.forEach(function (filename) {
+    _filenames.forEach(function(filename) {
       let sourceFilename = filename;
       if (commander.outFile) {
-        sourceFilename = path.relative(path.dirname(commander.outFile), sourceFilename);
+        sourceFilename = path.relative(
+          path.dirname(commander.outFile),
+          sourceFilename,
+        );
       }
       sourceFilename = slash(sourceFilename);
 
-      const data = util.compile(filename, defaults({
-        sourceFileName: sourceFilename,
-      }, opts));
+      const data = util.compile(
+        filename,
+        defaults(
+          {
+            sourceFileName: sourceFilename,
+          },
+          opts,
+        ),
+      );
 
       if (!data) return;
 
@@ -142,33 +166,36 @@ export default function (commander, filenames, opts) {
     output();
   };
 
-  const files = function () {
-
+  const files = function() {
     if (!commander.skipInitialBuild) {
       walk();
     }
 
     if (commander.watch) {
       const chokidar = util.requireChokidar();
-      chokidar.watch(filenames, {
-        persistent: true,
-        ignoreInitial: true,
-        awaitWriteFinish: {
-          stabilityThreshold: 50,
-          pollInterval: 10,
-        },
-      }).on("all", function (type, filename) {
-        if (!util.isCompilableExtension(filename, commander.extensions)) return;
-
-        if (type === "add" || type === "change") {
-          util.log(type + " " + filename);
-          try {
-            walk();
-          } catch (err) {
-            console.error(err.stack);
+      chokidar
+        .watch(filenames, {
+          persistent: true,
+          ignoreInitial: true,
+          awaitWriteFinish: {
+            stabilityThreshold: 50,
+            pollInterval: 10,
+          },
+        })
+        .on("all", function(type, filename) {
+          if (!util.isCompilableExtension(filename, commander.extensions)) {
+            return;
           }
-        }
-      });
+
+          if (type === "add" || type === "change") {
+            util.log(type + " " + filename);
+            try {
+              walk();
+            } catch (err) {
+              console.error(err.stack);
+            }
+          }
+        });
     }
   };
 
diff --git a/packages/babel-cli/src/babel/index.js b/packages/babel-cli/src/babel/index.js
index 42b949f952..4ac77fd051 100755
--- a/packages/babel-cli/src/babel/index.js
+++ b/packages/babel-cli/src/babel/index.js
@@ -34,45 +34,117 @@ function collect(value, previousValue): Array<string> {
 
 /* eslint-disable max-len */
 // Standard Babel input configs.
-commander.option("-f, --filename [filename]", "filename to use when reading from stdin - this will be used in source-maps, errors etc");
-commander.option("--presets [list]", "comma-separated list of preset names", collect);
-commander.option("--plugins [list]", "comma-separated list of plugin names", collect);
+commander.option(
+  "-f, --filename [filename]",
+  "filename to use when reading from stdin - this will be used in source-maps, errors etc",
+);
+commander.option(
+  "--presets [list]",
+  "comma-separated list of preset names",
+  collect,
+);
+commander.option(
+  "--plugins [list]",
+  "comma-separated list of plugin names",
+  collect,
+);
 
 // Basic file input configuration.
 commander.option("--source-type [script|module]", "");
-commander.option("--no-babelrc", "Whether or not to look up .babelrc and .babelignore files");
-commander.option("--ignore [list]", "list of glob paths to **not** compile", collect);
-commander.option("--only [list]", "list of glob paths to **only** compile", collect);
+commander.option(
+  "--no-babelrc",
+  "Whether or not to look up .babelrc and .babelignore files",
+);
+commander.option(
+  "--ignore [list]",
+  "list of glob paths to **not** compile",
+  collect,
+);
+commander.option(
+  "--only [list]",
+  "list of glob paths to **only** compile",
+  collect,
+);
 
 // Misc babel config.
-commander.option("--no-highlight-code", "enable/disable ANSI syntax highlighting of code frames (on by default)");
+commander.option(
+  "--no-highlight-code",
+  "enable/disable ANSI syntax highlighting of code frames (on by default)",
+);
 
 // General output formatting.
-commander.option("--no-comments", "write comments to generated output (true by default)");
-commander.option("--retain-lines", "retain line numbers - will result in really ugly code");
-commander.option("--compact [true|false|auto]", "do not include superfluous whitespace characters and line terminators", booleanify);
+commander.option(
+  "--no-comments",
+  "write comments to generated output (true by default)",
+);
+commander.option(
+  "--retain-lines",
+  "retain line numbers - will result in really ugly code",
+);
+commander.option(
+  "--compact [true|false|auto]",
+  "do not include superfluous whitespace characters and line terminators",
+  booleanify,
+);
 commander.option("--minified", "save as much bytes when printing [true|false]");
-commander.option("--auxiliary-comment-before [string]", "print a comment before any injected non-user code");
-commander.option("--auxiliary-comment-after [string]", "print a comment after any injected non-user code");
+commander.option(
+  "--auxiliary-comment-before [string]",
+  "print a comment before any injected non-user code",
+);
+commander.option(
+  "--auxiliary-comment-after [string]",
+  "print a comment after any injected non-user code",
+);
 
 // General soucemap formatting.
 commander.option("-s, --source-maps [true|false|inline|both]", "", booleanify);
-commander.option("--source-map-target [string]", "set `file` on returned source map");
-commander.option("--source-file-name [string]", "set `sources[0]` on returned source map");
-commander.option("--source-root [filename]", "the root from which all sources are relative");
+commander.option(
+  "--source-map-target [string]",
+  "set `file` on returned source map",
+);
+commander.option(
+  "--source-file-name [string]",
+  "set `sources[0]` on returned source map",
+);
+commander.option(
+  "--source-root [filename]",
+  "the root from which all sources are relative",
+);
 
 // Config params for certain module output formats.
-commander.option("--module-root [filename]", "optional prefix for the AMD module formatter that will be prepend to the filename on module definitions");
+commander.option(
+  "--module-root [filename]",
+  "optional prefix for the AMD module formatter that will be prepend to the filename on module definitions",
+);
 commander.option("-M, --module-ids", "insert an explicit id for modules");
-commander.option("--module-id [string]", "specify a custom name for module ids");
+commander.option(
+  "--module-id [string]",
+  "specify a custom name for module ids",
+);
 
 // "babel" command specific arguments that are not passed to babel-core.
-commander.option("-x, --extensions [extensions]", "List of extensions to compile when a directory has been input [.es6,.js,.es,.jsx,.mjs]", collect);
+commander.option(
+  "-x, --extensions [extensions]",
+  "List of extensions to compile when a directory has been input [.es6,.js,.es,.jsx,.mjs]",
+  collect,
+);
 commander.option("-w, --watch", "Recompile files on changes");
-commander.option("--skip-initial-build", "Do not compile files before watching");
-commander.option("-o, --out-file [out]", "Compile all input files into a single file");
-commander.option("-d, --out-dir [out]", "Compile an input directory of modules into an output directory");
-commander.option("-D, --copy-files", "When compiling a directory copy over non-compilable files");
+commander.option(
+  "--skip-initial-build",
+  "Do not compile files before watching",
+);
+commander.option(
+  "-o, --out-file [out]",
+  "Compile all input files into a single file",
+);
+commander.option(
+  "-d, --out-dir [out]",
+  "Compile an input directory of modules into an output directory",
+);
+commander.option(
+  "-D, --copy-files",
+  "When compiling a directory copy over non-compilable files",
+);
 commander.option("-q, --quiet", "Don't log anything");
 /* eslint-enable max-len */
 
@@ -84,7 +156,7 @@ commander.parse(process.argv);
 
 const errors = [];
 
-let filenames = commander.args.reduce(function (globbed, input) {
+let filenames = commander.args.reduce(function(globbed, input) {
   let files = glob.sync(input);
   if (!files.length) files = [input];
   return globbed.concat(files);
@@ -92,7 +164,7 @@ let filenames = commander.args.reduce(function (globbed, input) {
 
 filenames = uniq(filenames);
 
-filenames.forEach(function (filename) {
+filenames.forEach(function(filename) {
   if (!fs.existsSync(filename)) {
     errors.push(filename + " doesn't exist");
   }
diff --git a/packages/babel-cli/src/babel/util.js b/packages/babel-cli/src/babel/util.js
index 7f393b5101..3150b3753a 100644
--- a/packages/babel-cli/src/babel/util.js
+++ b/packages/babel-cli/src/babel/util.js
@@ -10,7 +10,7 @@ export function chmod(src, dest) {
 }
 
 export function readdirFilter(filename) {
-  return readdir(filename).filter(function (filename) {
+  return readdir(filename).filter(function(filename) {
     return isCompilableExtension(filename);
   });
 }
@@ -20,7 +20,10 @@ export { readdir };
 /**
  * Test if a filename ends with a compilable extension.
  */
-export function isCompilableExtension(filename: string, altExts?: Array<string>): boolean {
+export function isCompilableExtension(
+  filename: string,
+  altExts?: Array<string>,
+): boolean {
   const exts = altExts || babel.DEFAULT_EXTENSIONS;
   const ext = path.extname(filename);
   return includes(exts, ext);
@@ -63,7 +66,7 @@ function toErrorStack(err) {
   }
 }
 
-process.on("uncaughtException", function (err) {
+process.on("uncaughtException", function(err) {
   console.error(toErrorStack(err));
   process.exit(1);
 });
@@ -74,7 +77,7 @@ export function requireChokidar() {
   } catch (err) {
     console.error(
       "The optional dependency chokidar failed to install and is required for " +
-      "--watch. Chokidar is likely not supported on your platform."
+        "--watch. Chokidar is likely not supported on your platform.",
     );
     throw err;
   }
diff --git a/packages/babel-cli/test/index.js b/packages/babel-cli/test/index.js
index a5ebfbfc55..2bfaa02c71 100644
--- a/packages/babel-cli/test/index.js
+++ b/packages/babel-cli/test/index.js
@@ -27,34 +27,39 @@ const pluginLocs = [
   path.join(__dirname, "/../../babel-plugin-transform-es2015-modules-commonjs"),
 ].join(",");
 
-const readDir = function (loc, filter) {
+const readDir = function(loc, filter) {
   const files = {};
   if (fs.existsSync(loc)) {
-    readdir(loc, filter).forEach(function (filename) {
+    readdir(loc, filter).forEach(function(filename) {
       files[filename] = helper.readFile(path.join(loc, filename));
     });
   }
   return files;
 };
 
-const saveInFiles = function (files) {
+const saveInFiles = function(files) {
   // Place an empty .babelrc in each test so tests won't unexpectedly get to repo-level config.
   outputFileSync(".babelrc", "{}");
 
-  Object.keys(files).forEach(function (filename) {
+  Object.keys(files).forEach(function(filename) {
     const content = files[filename];
     outputFileSync(filename, content);
   });
 };
 
-const assertTest = function (stdout, stderr, opts) {
+const assertTest = function(stdout, stderr, opts) {
   const expectStderr = opts.stderr.trim();
   stderr = stderr.trim();
 
   if (opts.stderr) {
     if (opts.stderrContains) {
-      assert.ok(includes(stderr, expectStderr), "stderr " + JSON.stringify(stderr) +
-        " didn't contain " + JSON.stringify(expectStderr));
+      assert.ok(
+        includes(stderr, expectStderr),
+        "stderr " +
+          JSON.stringify(stderr) +
+          " didn't contain " +
+          JSON.stringify(expectStderr),
+      );
     } else {
       chai.expect(stderr).to.equal(expectStderr, "stderr didn't match");
     }
@@ -68,8 +73,13 @@ const assertTest = function (stdout, stderr, opts) {
 
   if (opts.stdout) {
     if (opts.stdoutContains) {
-      assert.ok(includes(stdout, expectStdout), "stdout " + JSON.stringify(stdout) +
-        " didn't contain " + JSON.stringify(expectStdout));
+      assert.ok(
+        includes(stdout, expectStdout),
+        "stdout " +
+          JSON.stringify(stdout) +
+          " didn't contain " +
+          JSON.stringify(expectStdout),
+      );
     } else {
       chai.expect(stdout).to.equal(expectStdout, "stdout didn't match");
     }
@@ -80,30 +90,34 @@ const assertTest = function (stdout, stderr, opts) {
   if (opts.outFiles) {
     const actualFiles = readDir(path.join(tmpLoc));
 
-    Object.keys(actualFiles).forEach(function (filename) {
+    Object.keys(actualFiles).forEach(function(filename) {
       if (!opts.inFiles.hasOwnProperty(filename)) {
         const expect = opts.outFiles[filename];
         const actual = actualFiles[filename];
 
-        chai.expect(expect, "Output is missing: " + filename).to.not.be.undefined;
+        chai.expect(expect, "Output is missing: " + filename).to.not.be
+          .undefined;
 
         if (expect) {
-          chai.expect(actual).to.equal(expect, "Compiled output does not match: " + filename);
+          chai
+            .expect(actual)
+            .to.equal(expect, "Compiled output does not match: " + filename);
         }
       }
     });
 
     Object.keys(opts.outFiles).forEach(function(filename) {
-      chai.expect(actualFiles, "Extraneous file in output: " + filename)
+      chai
+        .expect(actualFiles, "Extraneous file in output: " + filename)
         .to.contain.key(filename);
     });
   }
 };
 
-const buildTest = function (binName, testName, opts) {
+const buildTest = function(binName, testName, opts) {
   const binLoc = path.join(__dirname, "../lib", binName);
 
-  return function (callback) {
+  return function(callback) {
     clear();
     saveInFiles(opts.inFiles);
 
@@ -124,15 +138,15 @@ const buildTest = function (binName, testName, opts) {
     let stderr = "";
     let stdout = "";
 
-    spawn.stderr.on("data", function (chunk) {
+    spawn.stderr.on("data", function(chunk) {
       stderr += chunk;
     });
 
-    spawn.stdout.on("data", function (chunk) {
+    spawn.stdout.on("data", function(chunk) {
       stdout += chunk;
     });
 
-    spawn.on("close", function () {
+    spawn.on("close", function() {
       let err;
 
       try {
@@ -142,7 +156,8 @@ const buildTest = function (binName, testName, opts) {
       }
 
       if (err) {
-        err.message = args.map((arg) => `"${ arg }"`).join(" ") + ": " + err.message;
+        err.message =
+          args.map(arg => `"${arg}"`).join(" ") + ": " + err.message;
       }
 
       callback(err);
@@ -155,19 +170,19 @@ const buildTest = function (binName, testName, opts) {
   };
 };
 
-const clear = function () {
+const clear = function() {
   process.chdir(__dirname);
   if (fs.existsSync(tmpLoc)) rimraf.sync(tmpLoc);
   fs.mkdirSync(tmpLoc);
   process.chdir(tmpLoc);
 };
 
-fs.readdirSync(fixtureLoc).forEach(function (binName) {
+fs.readdirSync(fixtureLoc).forEach(function(binName) {
   if (binName[0] === ".") return;
 
   const suiteLoc = path.join(fixtureLoc, binName);
-  describe("bin/" + binName, function () {
-    fs.readdirSync(suiteLoc).forEach(function (testName) {
+  describe("bin/" + binName, function() {
+    fs.readdirSync(suiteLoc).forEach(function(testName) {
       if (testName[0] === ".") return;
 
       const testLoc = path.join(suiteLoc, testName);
@@ -179,7 +194,7 @@ fs.readdirSync(fixtureLoc).forEach(function (binName) {
       const optionsLoc = path.join(testLoc, "options.json");
       if (fs.existsSync(optionsLoc)) merge(opts, require(optionsLoc));
 
-      ["stdout", "stdin", "stderr"].forEach(function (key) {
+      ["stdout", "stdin", "stderr"].forEach(function(key) {
         const loc = path.join(testLoc, key + ".txt");
         if (fs.existsSync(loc)) {
           opts[key] = helper.readFile(loc);
diff --git a/packages/babel-code-frame/src/index.js b/packages/babel-code-frame/src/index.js
index f8564a0a23..cb1901d160 100644
--- a/packages/babel-code-frame/src/index.js
+++ b/packages/babel-code-frame/src/index.js
@@ -90,11 +90,11 @@ function getTokenType(match) {
  */
 
 function highlight(defs: Object, text: string) {
-  return text.replace(jsTokens, function (...args) {
+  return text.replace(jsTokens, function(...args) {
     const type = getTokenType(args);
     const colorize = defs[type];
     if (colorize) {
-      return args[0].split(NEWLINE).map((str) => colorize(str)).join("\n");
+      return args[0].split(NEWLINE).map(str => colorize(str)).join("\n");
     } else {
       return args[0];
     }
@@ -106,9 +106,15 @@ function highlight(defs: Object, text: string) {
  */
 
 function getMarkerLines(
-  loc: NodeLocation, source: Array<string>, opts: Object
+  loc: NodeLocation,
+  source: Array<string>,
+  opts: Object,
 ): { start: number, end: number, markerLines: Object } {
-  const startLoc: Location = Object.assign({}, { column: 0, line: -1 }, loc.start);
+  const startLoc: Location = Object.assign(
+    {},
+    { column: 0, line: -1 },
+    loc.start,
+  );
   const endLoc: Location = Object.assign({}, startLoc, loc.end);
   const linesAbove = opts.linesAbove || 2;
   const linesBelow = opts.linesBelow || 3;
@@ -165,12 +171,13 @@ function getMarkerLines(
   return { start, end, markerLines };
 }
 
-export function codeFrameColumns (
+export function codeFrameColumns(
   rawLines: string,
   loc: NodeLocation,
   opts: Object = {},
 ): string {
-  const highlighted = (opts.highlightCode && Chalk.supportsColor) || opts.forceColor;
+  const highlighted =
+    (opts.highlightCode && Chalk.supportsColor) || opts.forceColor;
   let chalk = Chalk;
   if (opts.forceColor) {
     chalk = new Chalk.constructor({ enabled: true });
@@ -186,34 +193,39 @@ export function codeFrameColumns (
 
   const numberMaxWidth = String(end).length;
 
-  const frame = lines.slice(start, end).map((line, index) => {
-    const number = start + 1 + index;
-    const paddedNumber = ` ${number}`.slice(-numberMaxWidth);
-    const gutter = ` ${paddedNumber} | `;
-    const hasMarker = markerLines[number];
-    if (hasMarker) {
-      let markerLine = "";
-      if (Array.isArray(hasMarker)) {
-        const markerSpacing = line.slice(0, Math.max(hasMarker[0] - 1, 0)).replace(/[^\t]/g, " ");
-        const numberOfMarkers = hasMarker[1] || 1;
+  const frame = lines
+    .slice(start, end)
+    .map((line, index) => {
+      const number = start + 1 + index;
+      const paddedNumber = ` ${number}`.slice(-numberMaxWidth);
+      const gutter = ` ${paddedNumber} | `;
+      const hasMarker = markerLines[number];
+      if (hasMarker) {
+        let markerLine = "";
+        if (Array.isArray(hasMarker)) {
+          const markerSpacing = line
+            .slice(0, Math.max(hasMarker[0] - 1, 0))
+            .replace(/[^\t]/g, " ");
+          const numberOfMarkers = hasMarker[1] || 1;
 
-        markerLine = [
-          "\n ",
-          maybeHighlight(defs.gutter, gutter.replace(/\d/g, " ")),
-          markerSpacing,
-          maybeHighlight(defs.marker, "^").repeat(numberOfMarkers),
+          markerLine = [
+            "\n ",
+            maybeHighlight(defs.gutter, gutter.replace(/\d/g, " ")),
+            markerSpacing,
+            maybeHighlight(defs.marker, "^").repeat(numberOfMarkers),
+          ].join("");
+        }
+        return [
+          maybeHighlight(defs.marker, ">"),
+          maybeHighlight(defs.gutter, gutter),
+          line,
+          markerLine,
         ].join("");
+      } else {
+        return ` ${maybeHighlight(defs.gutter, gutter)}${line}`;
       }
-      return [
-        maybeHighlight(defs.marker, ">"),
-        maybeHighlight(defs.gutter, gutter),
-        line,
-        markerLine,
-      ].join("");
-    } else {
-      return ` ${maybeHighlight(defs.gutter, gutter)}${line}`;
-    }
-  }).join("\n");
+    })
+    .join("\n");
 
   if (highlighted) {
     return chalk.reset(frame);
@@ -226,7 +238,7 @@ export function codeFrameColumns (
  * Create a code frame, adding line numbers, code highlighting, and pointing to a given position.
  */
 
-export default function (
+export default function(
   rawLines: string,
   lineNumber: number,
   colNumber: ?number,
@@ -236,7 +248,7 @@ export default function (
     deprecationWarningShown = true;
 
     const deprecationError = new Error(
-      "Passing lineNumber and colNumber is deprecated to babel-code-frame. Please use `codeFrameColumns`."
+      "Passing lineNumber and colNumber is deprecated to babel-code-frame. Please use `codeFrameColumns`.",
     );
     deprecationError.name = "DeprecationWarning";
 
@@ -249,7 +261,9 @@ export default function (
 
   colNumber = Math.max(colNumber, 0);
 
-  const location: NodeLocation = { start: { column: colNumber, line: lineNumber } };
+  const location: NodeLocation = {
+    start: { column: colNumber, line: lineNumber },
+  };
 
   return codeFrameColumns(rawLines, location, opts);
 }
diff --git a/packages/babel-code-frame/test/index.js b/packages/babel-code-frame/test/index.js
index a0a1223463..5892b7a443 100644
--- a/packages/babel-code-frame/test/index.js
+++ b/packages/babel-code-frame/test/index.js
@@ -2,35 +2,29 @@ import assert from "assert";
 import chalk from "chalk";
 import codeFrame, { codeFrameColumns } from "..";
 
-describe("babel-code-frame", function () {
-  it("basic usage", function () {
-    const rawLines = [
-      "class Foo {",
-      "  constructor()",
-      "};",
-    ].join("\n");
-    assert.equal(codeFrame(rawLines, 2, 16), [
-      "  1 | class Foo {",
-      "> 2 |   constructor()",
-      "    |                ^",
-      "  3 | };",
-    ].join("\n"));
+describe("babel-code-frame", function() {
+  it("basic usage", function() {
+    const rawLines = ["class Foo {", "  constructor()", "};"].join("\n");
+    assert.equal(
+      codeFrame(rawLines, 2, 16),
+      [
+        "  1 | class Foo {",
+        "> 2 |   constructor()",
+        "    |                ^",
+        "  3 | };",
+      ].join("\n"),
+    );
   });
 
-  it("optional column number", function () {
-    const rawLines = [
-      "class Foo {",
-      "  constructor()",
-      "};",
-    ].join("\n");
-    assert.equal(codeFrame(rawLines, 2, null), [
-      "  1 | class Foo {",
-      "> 2 |   constructor()",
-      "  3 | };",
-    ].join("\n"));
+  it("optional column number", function() {
+    const rawLines = ["class Foo {", "  constructor()", "};"].join("\n");
+    assert.equal(
+      codeFrame(rawLines, 2, null),
+      ["  1 | class Foo {", "> 2 |   constructor()", "  3 | };"].join("\n"),
+    );
   });
 
-  it("maximum context lines and padding", function () {
+  it("maximum context lines and padding", function() {
     const rawLines = [
       "/**",
       " * Sums two numbers.",
@@ -44,18 +38,21 @@ describe("babel-code-frame", function () {
       "  return a + b",
       "}",
     ].join("\n");
-    assert.equal(codeFrame(rawLines, 7, 2), [
-      "   5 |  * @param b Number",
-      "   6 |  * @returns Number",
-      ">  7 |  */",
-      "     |  ^",
-      "   8 | ",
-      "   9 | function sum(a, b) {",
-      "  10 |   return a + b",
-    ].join("\n"));
+    assert.equal(
+      codeFrame(rawLines, 7, 2),
+      [
+        "   5 |  * @param b Number",
+        "   6 |  * @returns Number",
+        ">  7 |  */",
+        "     |  ^",
+        "   8 | ",
+        "   9 | function sum(a, b) {",
+        "  10 |   return a + b",
+      ].join("\n"),
+    );
   });
 
-  it("no unnecessary padding due to one-off errors", function () {
+  it("no unnecessary padding due to one-off errors", function() {
     const rawLines = [
       "/**",
       " * Sums two numbers.",
@@ -69,43 +66,49 @@ describe("babel-code-frame", function () {
       "  return a + b",
       "}",
     ].join("\n");
-    assert.equal(codeFrame(rawLines, 6, 2), [
-      "  4 |  * @param a Number",
-      "  5 |  * @param b Number",
-      "> 6 |  * @returns Number",
-      "    |  ^",
-      "  7 |  */",
-      "  8 | ",
-      "  9 | function sum(a, b) {",
-    ].join("\n"));
+    assert.equal(
+      codeFrame(rawLines, 6, 2),
+      [
+        "  4 |  * @param a Number",
+        "  5 |  * @param b Number",
+        "> 6 |  * @returns Number",
+        "    |  ^",
+        "  7 |  */",
+        "  8 | ",
+        "  9 | function sum(a, b) {",
+      ].join("\n"),
+    );
   });
 
-  it("tabs", function () {
+  it("tabs", function() {
     const rawLines = [
       "\tclass Foo {",
       "\t  \t\t    constructor\t(\t)",
       "\t};",
     ].join("\n");
-    assert.equal(codeFrame(rawLines, 2, 25), [
-      "  1 | \tclass Foo {",
-      "> 2 | \t  \t\t    constructor\t(\t)",
-      "    | \t  \t\t               \t \t ^",
-      "  3 | \t};",
-    ].join("\n"));
+    assert.equal(
+      codeFrame(rawLines, 2, 25),
+      [
+        "  1 | \tclass Foo {",
+        "> 2 | \t  \t\t    constructor\t(\t)",
+        "    | \t  \t\t               \t \t ^",
+        "  3 | \t};",
+      ].join("\n"),
+    );
   });
 
-  it("opts.highlightCode", function () {
+  it("opts.highlightCode", function() {
     const rawLines = "console.log('babel')";
     const result = codeFrame(rawLines, 1, 9, { highlightCode: true });
     const stripped = chalk.stripColor(result);
     assert.ok(result.length > stripped.length);
-    assert.equal(stripped, [
-      "> 1 | console.log('babel')",
-      "    |         ^",
-    ].join("\n"));
+    assert.equal(
+      stripped,
+      ["> 1 | console.log('babel')", "    |         ^"].join("\n"),
+    );
   });
 
-  it("opts.linesAbove", function () {
+  it("opts.linesAbove", function() {
     const rawLines = [
       "/**",
       " * Sums two numbers.",
@@ -119,17 +122,20 @@ describe("babel-code-frame", function () {
       "  return a + b",
       "}",
     ].join("\n");
-    assert.equal(codeFrame(rawLines, 7, 2, { linesAbove: 1 }), [
-      "   6 |  * @returns Number",
-      ">  7 |  */",
-      "     |  ^",
-      "   8 | ",
-      "   9 | function sum(a, b) {",
-      "  10 |   return a + b",
-    ].join("\n"));
+    assert.equal(
+      codeFrame(rawLines, 7, 2, { linesAbove: 1 }),
+      [
+        "   6 |  * @returns Number",
+        ">  7 |  */",
+        "     |  ^",
+        "   8 | ",
+        "   9 | function sum(a, b) {",
+        "  10 |   return a + b",
+      ].join("\n"),
+    );
   });
 
-  it("opts.linesBelow", function () {
+  it("opts.linesBelow", function() {
     const rawLines = [
       "/**",
       " * Sums two numbers.",
@@ -143,16 +149,19 @@ describe("babel-code-frame", function () {
       "  return a + b",
       "}",
     ].join("\n");
-    assert.equal(codeFrame(rawLines, 7, 2, { linesBelow: 1 }), [
-      "  5 |  * @param b Number",
-      "  6 |  * @returns Number",
-      "> 7 |  */",
-      "    |  ^",
-      "  8 | ",
-    ].join("\n"));
+    assert.equal(
+      codeFrame(rawLines, 7, 2, { linesBelow: 1 }),
+      [
+        "  5 |  * @param b Number",
+        "  6 |  * @returns Number",
+        "> 7 |  */",
+        "    |  ^",
+        "  8 | ",
+      ].join("\n"),
+    );
   });
 
-  it("opts.linesAbove and opts.linesBelow", function () {
+  it("opts.linesAbove and opts.linesBelow", function() {
     const rawLines = [
       "/**",
       " * Sums two numbers.",
@@ -166,78 +175,82 @@ describe("babel-code-frame", function () {
       "  return a + b",
       "}",
     ].join("\n");
-    assert.equal(codeFrame(rawLines, 7, 2, { linesAbove: 1, linesBelow: 1 }), [
-      "  6 |  * @returns Number",
-      "> 7 |  */",
-      "    |  ^",
-      "  8 | ",
-    ].join("\n"));
+    assert.equal(
+      codeFrame(rawLines, 7, 2, { linesAbove: 1, linesBelow: 1 }),
+      ["  6 |  * @returns Number", "> 7 |  */", "    |  ^", "  8 | "].join(
+        "\n",
+      ),
+    );
   });
 
   it("opts.forceColor", function() {
     const marker = chalk.red.bold;
     const gutter = chalk.grey;
 
-    const rawLines = [
-      "",
-      "",
-      "",
-      "",
-    ].join("\n");
-    assert.equal(codeFrame(rawLines, 3, null, { linesAbove: 1, linesBelow: 1, forceColor: true }),
-      chalk.reset([
-        " " + gutter(" 2 | "),
-        marker(">") + gutter(" 3 | "),
-        " " + gutter(" 4 | "),
-      ].join("\n"))
+    const rawLines = ["", "", "", ""].join("\n");
+    assert.equal(
+      codeFrame(rawLines, 3, null, {
+        linesAbove: 1,
+        linesBelow: 1,
+        forceColor: true,
+      }),
+      chalk.reset(
+        [
+          " " + gutter(" 2 | "),
+          marker(">") + gutter(" 3 | "),
+          " " + gutter(" 4 | "),
+        ].join("\n"),
+      ),
     );
   });
 
-  it("basic usage, new API", function () {
-    const rawLines = [
-      "class Foo {",
-      "  constructor()",
-      "};",
-    ].join("\n");
-    assert.equal(codeFrameColumns(rawLines, { start: { line: 2, column: 16 } }), [
-      "  1 | class Foo {",
-      "> 2 |   constructor()",
-      "    |                ^",
-      "  3 | };",
-    ].join("\n"));
+  it("basic usage, new API", function() {
+    const rawLines = ["class Foo {", "  constructor()", "};"].join("\n");
+    assert.equal(
+      codeFrameColumns(rawLines, { start: { line: 2, column: 16 } }),
+      [
+        "  1 | class Foo {",
+        "> 2 |   constructor()",
+        "    |                ^",
+        "  3 | };",
+      ].join("\n"),
+    );
   });
 
   it("mark multiple columns", function() {
-    const rawLines = [
-      "class Foo {",
-      "  constructor()",
-      "};",
-    ].join("\n");
+    const rawLines = ["class Foo {", "  constructor()", "};"].join("\n");
     assert.equal(
-      codeFrameColumns(rawLines, { start: { line: 2, column: 3 }, end: { line: 2, column: 16 } }), [
+      codeFrameColumns(rawLines, {
+        start: { line: 2, column: 3 },
+        end: { line: 2, column: 16 },
+      }),
+      [
         "  1 | class Foo {",
         "> 2 |   constructor()",
         "    |   ^^^^^^^^^^^^^",
         "  3 | };",
-      ].join("\n"));
+      ].join("\n"),
+    );
   });
 
   it("mark multiple columns across lines", function() {
-    const rawLines = [
-      "class Foo {",
-      "  constructor() {",
-      "  }",
-      "};",
-    ].join("\n");
+    const rawLines = ["class Foo {", "  constructor() {", "  }", "};"].join(
+      "\n",
+    );
     assert.equal(
-      codeFrameColumns(rawLines, { start: { line: 2, column: 17 }, end: { line: 3, column: 3 } }), [
+      codeFrameColumns(rawLines, {
+        start: { line: 2, column: 17 },
+        end: { line: 3, column: 3 },
+      }),
+      [
         "  1 | class Foo {",
         "> 2 |   constructor() {",
         "    |                 ^",
         "> 3 |   }",
         "    | ^^^",
         "  4 | };",
-      ].join("\n"));
+      ].join("\n"),
+    );
   });
 
   it("mark multiple columns across multiple lines", function() {
@@ -249,7 +262,11 @@ describe("babel-code-frame", function () {
       "};",
     ].join("\n");
     assert.equal(
-      codeFrameColumns(rawLines, { start: { line: 2, column: 17 }, end: { line: 4, column: 3 } }), [
+      codeFrameColumns(rawLines, {
+        start: { line: 2, column: 17 },
+        end: { line: 4, column: 3 },
+      }),
+      [
         "  1 | class Foo {",
         "> 2 |   constructor() {",
         "    |                 ^",
@@ -258,7 +275,8 @@ describe("babel-code-frame", function () {
         "> 4 |   }",
         "    | ^^^",
         "  5 | };",
-      ].join("\n"));
+      ].join("\n"),
+    );
   });
 
   it("mark across multiple lines without columns", function() {
@@ -270,12 +288,14 @@ describe("babel-code-frame", function () {
       "};",
     ].join("\n");
     assert.equal(
-      codeFrameColumns(rawLines, { start: { line: 2 }, end: { line: 4 } }), [
+      codeFrameColumns(rawLines, { start: { line: 2 }, end: { line: 4 } }),
+      [
         "  1 | class Foo {",
         "> 2 |   constructor() {",
         "> 3 |     console.log(arguments);",
         "> 4 |   }",
         "  5 | };",
-      ].join("\n"));
+      ].join("\n"),
+    );
   });
 });
diff --git a/packages/babel-core/src/config/build-config-chain.js b/packages/babel-core/src/config/build-config-chain.js
index 7c9813f14d..dd10f3166c 100644
--- a/packages/babel-core/src/config/build-config-chain.js
+++ b/packages/babel-core/src/config/build-config-chain.js
@@ -7,14 +7,14 @@ import micromatch from "micromatch";
 import { findConfigs, loadConfig } from "./loading/files";
 
 type ConfigItem = {
-  type: "options"|"arguments",
+  type: "options" | "arguments",
   options: {},
   dirname: string,
   alias: string,
   loc: string,
 };
 
-export default function buildConfigChain(opts: {}): Array<ConfigItem>|null {
+export default function buildConfigChain(opts: {}): Array<ConfigItem> | null {
   if (typeof opts.filename !== "string" && opts.filename != null) {
     throw new Error(".filename must be a string, null, or undefined");
   }
@@ -44,9 +44,9 @@ export default function buildConfigChain(opts: {}): Array<ConfigItem>|null {
 }
 
 class ConfigChainBuilder {
-  filename: string|null;
+  filename: string | null;
   configs: Array<ConfigItem>;
-  possibleDirs: null|Array<string>;
+  possibleDirs: null | Array<string>;
 
   constructor(filename) {
     this.configs = [];
@@ -57,16 +57,14 @@ class ConfigChainBuilder {
   /**
    * Tests if a filename should be ignored based on "ignore" and "only" options.
    */
-  shouldIgnore(
-    ignore: mixed,
-    only: mixed,
-    dirname: string,
-  ): boolean {
+  shouldIgnore(ignore: mixed, only: mixed, dirname: string): boolean {
     if (!this.filename) return false;
 
     if (ignore) {
       if (!Array.isArray(ignore)) {
-        throw new Error(`.ignore should be an array, ${JSON.stringify(ignore)} given`);
+        throw new Error(
+          `.ignore should be an array, ${JSON.stringify(ignore)} given`,
+        );
       }
 
       if (this.matchesPatterns(ignore, dirname)) return true;
@@ -74,7 +72,9 @@ class ConfigChainBuilder {
 
     if (only) {
       if (!Array.isArray(only)) {
-        throw new Error(`.only should be an array, ${JSON.stringify(only)} given`);
+        throw new Error(
+          `.only should be an array, ${JSON.stringify(only)} given`,
+        );
       }
 
       if (!this.matchesPatterns(only, dirname)) return true;
@@ -89,21 +89,27 @@ class ConfigChainBuilder {
    */
   matchesPatterns(patterns: Array<mixed>, dirname: string) {
     const filename = this.filename;
-    if (!filename) throw new Error("Assertion failure: .filename should always exist here");
+    if (!filename) {
+      throw new Error("Assertion failure: .filename should always exist here");
+    }
 
     const res = [];
     const strings = [];
     const fns = [];
 
-    patterns.forEach((pattern) => {
+    patterns.forEach(pattern => {
       if (typeof pattern === "string") strings.push(pattern);
       else if (typeof pattern === "function") fns.push(pattern);
       else if (pattern instanceof RegExp) res.push(pattern);
-      else throw new Error("Patterns must be a string, function, or regular expression");
+      else {
+        throw new Error(
+          "Patterns must be a string, function, or regular expression",
+        );
+      }
     });
 
-    if (res.some((re) => re.test(filename))) return true;
-    if (fns.some((fn) => fn(filename))) return true;
+    if (res.some(re => re.test(filename))) return true;
+    if (fns.some(fn => fn(filename))) return true;
 
     if (strings.length > 0) {
       let possibleDirs = this.possibleDirs;
@@ -123,7 +129,7 @@ class ConfigChainBuilder {
         }
       }
 
-      const absolutePatterns = strings.map((pattern) => {
+      const absolutePatterns = strings.map(pattern => {
         // Preserve the "!" prefix so that micromatch can use it for negation.
         const negate = pattern[0] === "!";
         if (negate) pattern = pattern.slice(1);
@@ -131,7 +137,9 @@ class ConfigChainBuilder {
         return (negate ? "!" : "") + path.resolve(dirname, pattern);
       });
 
-      if (micromatch(possibleDirs, absolutePatterns, { nocase: true }).length > 0) {
+      if (
+        micromatch(possibleDirs, absolutePatterns, { nocase: true }).length > 0
+      ) {
         return true;
       }
     }
@@ -150,16 +158,16 @@ class ConfigChainBuilder {
     });
   }
 
-  mergeConfig({
-    type,
-    options: rawOpts,
-    alias,
-    dirname,
-  }) {
+  mergeConfig({ type, options: rawOpts, alias, dirname }) {
     // Bail out ASAP if this file is ignored so that we run as little logic as possible on ignored files.
-    if (this.filename && this.shouldIgnore(rawOpts.ignore || null, rawOpts.only || null, dirname)) {
+    if (
+      this.filename &&
+      this.shouldIgnore(rawOpts.ignore || null, rawOpts.only || null, dirname)
+    ) {
       // TODO(logan): This is a really cross way to bail out. Avoid this in rewrite.
-      throw Object.assign((new Error("This file has been ignored."): any), { code: "BABEL_IGNORED_FILE" });
+      throw Object.assign((new Error("This file has been ignored."): any), {
+        code: "BABEL_IGNORED_FILE",
+      });
     }
 
     const options = Object.assign({}, rawOpts);
@@ -168,13 +176,19 @@ class ConfigChainBuilder {
 
     const envKey = getEnv();
 
-    if (rawOpts.env != null && (typeof rawOpts.env !== "object" || Array.isArray(rawOpts.env))) {
+    if (
+      rawOpts.env != null &&
+      (typeof rawOpts.env !== "object" || Array.isArray(rawOpts.env))
+    ) {
       throw new Error(".env block must be an object, null, or undefined");
     }
 
     const envOpts = rawOpts.env && rawOpts.env[envKey];
 
-    if (envOpts != null && (typeof envOpts !== "object" || Array.isArray(envOpts))) {
+    if (
+      envOpts != null &&
+      (typeof envOpts !== "object" || Array.isArray(envOpts))
+    ) {
       throw new Error(".env[...] block must be an object, null, or undefined");
     }
 
@@ -196,11 +210,13 @@ class ConfigChainBuilder {
     });
 
     if (rawOpts.extends) {
-      if (typeof rawOpts.extends !== "string") throw new Error(".extends must be a string");
+      if (typeof rawOpts.extends !== "string") {
+        throw new Error(".extends must be a string");
+      }
 
       const extendsConfig = loadConfig(rawOpts.extends, dirname);
 
-      const existingConfig = this.configs.some((config) => {
+      const existingConfig = this.configs.some(config => {
         return config.alias === extendsConfig.filepath;
       });
       if (!existingConfig) {
@@ -214,4 +230,3 @@ class ConfigChainBuilder {
     }
   }
 }
-
diff --git a/packages/babel-core/src/config/caching.js b/packages/babel-core/src/config/caching.js
index 7f27735874..24d3e748bb 100644
--- a/packages/babel-core/src/config/caching.js
+++ b/packages/babel-core/src/config/caching.js
@@ -13,7 +13,7 @@ type CacheConfiguratorObj = {
   invalidate: <T>(handler: () => T) => T,
 };
 
-type CacheEntry<ResultT> = Array<[ ResultT, () => boolean ]>;
+type CacheEntry<ResultT> = Array<[ResultT, () => boolean]>;
 
 /**
  * Given a function with a single argument, cache its results based on its argument and how it
@@ -22,7 +22,7 @@ type CacheEntry<ResultT> = Array<[ ResultT, () => boolean ]>;
 export function makeStrongCache<ArgT, ResultT>(
   handler: (ArgT, CacheConfigurator) => ResultT,
   autoPermacache?: boolean,
-): (ArgT) => ResultT {
+): ArgT => ResultT {
   return makeCachedFunction(new Map(), handler, autoPermacache);
 }
 
@@ -34,22 +34,24 @@ export function makeStrongCache<ArgT, ResultT>(
 export function makeWeakCache<ArgT: {}, ResultT>(
   handler: (ArgT, CacheConfigurator) => ResultT,
   autoPermacache?: boolean,
-): (ArgT) => ResultT {
+): ArgT => ResultT {
   return makeCachedFunction(new WeakMap(), handler, autoPermacache);
 }
 
-type CacheMap<ArgT, ResultT> = Map<ArgT, CacheEntry<ResultT>>|WeakMap<ArgT, CacheEntry<ResultT>>;
+type CacheMap<ArgT, ResultT> =
+  | Map<ArgT, CacheEntry<ResultT>>
+  | WeakMap<ArgT, CacheEntry<ResultT>>;
 
 function makeCachedFunction<ArgT, ResultT, Cache: CacheMap<ArgT, ResultT>>(
   callCache: Cache,
   handler: (ArgT, CacheConfigurator) => ResultT,
   autoPermacache: boolean = true,
-): (ArgT) => ResultT {
+): ArgT => ResultT {
   return function cachedFunction(arg) {
-    let cachedValue: CacheEntry<ResultT>|void = callCache.get(arg);
+    let cachedValue: CacheEntry<ResultT> | void = callCache.get(arg);
 
     if (cachedValue) {
-      for (const [ value, valid ] of cachedValue) {
+      for (const [value, valid] of cachedValue) {
         if (valid()) return value;
       }
     }
@@ -64,55 +66,53 @@ function makeCachedFunction<ArgT, ResultT, Cache: CacheMap<ArgT, ResultT>>(
 
     if (!result.configured) {
       // eslint-disable-next-line max-len
-      throw new Error([
-        "Caching was left unconfigured. Babel's plugins, presets, and .babelrc.js files can be configured",
-        "for various types of caching, using the first param of their handler functions:",
-        "",
-        "module.exports = function(api) {",
-        "  // The API exposes the following:",
-        "",
-        "  // Cache the returned value forever and don't call this function again.",
-        "  api.cache(true);",
-        "",
-        "  // Don't cache at all. Not recommended because it will be very slow.",
-        "  api.cache(false);",
-        "",
-        "  // Cached based on the value of some function. If this function returns a value different from",
-        "  // a previously-encountered value, the plugins will re-evaluate.",
-        "  var env = api.cache(() => process.env.NODE_ENV);",
-        "",
-        "  // If testing for a specific env, we recommend specifics to avoid instantiating a plugin for",
-        "  // any possible NODE_ENV value that might come up during plugin execution.",
-        "  var isProd = api.cache(() => process.env.NODE_ENV === \"production\");",
-        "",
-        "  // .cache(fn) will perform a linear search though instances to find the matching plugin based",
-        "  // based on previous instantiated plugins. If you want to recreate the plugin and discard the",
-        "  // previous instance whenever something changes, you may use:",
-        "  var isProd = api.cache.invalidate(() => process.env.NODE_ENV === \"production\");",
-        "",
-        "  // Note, we also expose the following more-verbose versions of the above examples:",
-        "  api.cache.forever(); // api.cache(true)",
-        "  api.cache.never();   // api.cache(false)",
-        "  api.cache.using(fn); // api.cache(fn)",
-        "",
-        "  // Return the value that will be cached.",
-        "  return { };",
-        "};",
-      ].join("\n"));
+      throw new Error(
+        [
+          "Caching was left unconfigured. Babel's plugins, presets, and .babelrc.js files can be configured",
+          "for various types of caching, using the first param of their handler functions:",
+          "",
+          "module.exports = function(api) {",
+          "  // The API exposes the following:",
+          "",
+          "  // Cache the returned value forever and don't call this function again.",
+          "  api.cache(true);",
+          "",
+          "  // Don't cache at all. Not recommended because it will be very slow.",
+          "  api.cache(false);",
+          "",
+          "  // Cached based on the value of some function. If this function returns a value different from",
+          "  // a previously-encountered value, the plugins will re-evaluate.",
+          "  var env = api.cache(() => process.env.NODE_ENV);",
+          "",
+          "  // If testing for a specific env, we recommend specifics to avoid instantiating a plugin for",
+          "  // any possible NODE_ENV value that might come up during plugin execution.",
+          '  var isProd = api.cache(() => process.env.NODE_ENV === "production");',
+          "",
+          "  // .cache(fn) will perform a linear search though instances to find the matching plugin based",
+          "  // based on previous instantiated plugins. If you want to recreate the plugin and discard the",
+          "  // previous instance whenever something changes, you may use:",
+          '  var isProd = api.cache.invalidate(() => process.env.NODE_ENV === "production");',
+          "",
+          "  // Note, we also expose the following more-verbose versions of the above examples:",
+          "  api.cache.forever(); // api.cache(true)",
+          "  api.cache.never();   // api.cache(false)",
+          "  api.cache.using(fn); // api.cache(fn)",
+          "",
+          "  // Return the value that will be cached.",
+          "  return { };",
+          "};",
+        ].join("\n"),
+      );
     }
 
     if (!result.never) {
       if (result.forever) {
-        cachedValue = [
-          [value, () => true],
-        ];
+        cachedValue = [[value, () => true]];
       } else if (result.invalidate) {
-        cachedValue = [
-          [value, result.valid],
-        ];
+        cachedValue = [[value, result.valid]];
       } else {
         cachedValue = cachedValue || [];
-        cachedValue.push([ value, result.valid ]);
+        cachedValue.push([value, result.valid]);
       }
       callCache.set(arg, cachedValue);
     }
@@ -121,7 +121,11 @@ function makeCachedFunction<ArgT, ResultT, Cache: CacheMap<ArgT, ResultT>>(
   };
 }
 
-function makeCacheConfig(): { cache: CacheConfigurator, result: *, deactivate: () => void } {
+function makeCacheConfig(): {
+  cache: CacheConfigurator,
+  result: *,
+  deactivate: () => void,
+} {
   const pairs = [];
 
   const result = {
@@ -137,51 +141,80 @@ function makeCacheConfig(): { cache: CacheConfigurator, result: *, deactivate: (
     active = false;
   };
 
-  const cache: CacheConfigurator = Object.assign((function cacheFn(val) {
-    if (typeof val === "boolean") {
-      if (val) cache.forever();
-      else cache.never();
-      return;
-    }
-
-    return cache.using(val);
-  }: any), ({
-    forever() {
-      if (!active) throw new Error("Cannot change caching after evaluation has completed.");
-      if (result.never) throw new Error("Caching has already been configured with .never()");
-      result.forever = true;
-      result.configured = true;
-    },
-    never() {
-      if (!active) throw new Error("Cannot change caching after evaluation has completed.");
-      if (result.forever) throw new Error("Caching has already been configured with .forever()");
-      result.never = true;
-      result.configured = true;
-    },
-    using<T>(handler: () => T): T {
-      if (!active) throw new Error("Cannot change caching after evaluation has completed.");
-      if (result.never || result.forever) {
-        throw new Error("Caching has already been configured with .never or .forever()");
+  const cache: CacheConfigurator = Object.assign(
+    (function cacheFn(val) {
+      if (typeof val === "boolean") {
+        if (val) cache.forever();
+        else cache.never();
+        return;
       }
-      result.configured = true;
 
-      const key = handler();
-      pairs.push([ key, handler ]);
-      return key;
-    },
-    invalidate<T>(handler: () => T): T {
-      if (!active) throw new Error("Cannot change caching after evaluation has completed.");
-      if (result.never || result.forever) {
-        throw new Error("Caching has already been configured with .never or .forever()");
-      }
-      result.invalidate = true;
-      result.configured = true;
+      return cache.using(val);
+    }: any),
+    ({
+      forever() {
+        if (!active) {
+          throw new Error(
+            "Cannot change caching after evaluation has completed.",
+          );
+        }
+        if (result.never) {
+          throw new Error("Caching has already been configured with .never()");
+        }
+        result.forever = true;
+        result.configured = true;
+      },
+      never() {
+        if (!active) {
+          throw new Error(
+            "Cannot change caching after evaluation has completed.",
+          );
+        }
+        if (result.forever) {
+          throw new Error(
+            "Caching has already been configured with .forever()",
+          );
+        }
+        result.never = true;
+        result.configured = true;
+      },
+      using<T>(handler: () => T): T {
+        if (!active) {
+          throw new Error(
+            "Cannot change caching after evaluation has completed.",
+          );
+        }
+        if (result.never || result.forever) {
+          throw new Error(
+            "Caching has already been configured with .never or .forever()",
+          );
+        }
+        result.configured = true;
 
-      const key = handler();
-      pairs.push([ key, handler ]);
-      return key;
-    },
-  }: CacheConfiguratorObj));
+        const key = handler();
+        pairs.push([key, handler]);
+        return key;
+      },
+      invalidate<T>(handler: () => T): T {
+        if (!active) {
+          throw new Error(
+            "Cannot change caching after evaluation has completed.",
+          );
+        }
+        if (result.never || result.forever) {
+          throw new Error(
+            "Caching has already been configured with .never or .forever()",
+          );
+        }
+        result.invalidate = true;
+        result.configured = true;
+
+        const key = handler();
+        pairs.push([key, handler]);
+        return key;
+      },
+    }: CacheConfiguratorObj),
+  );
 
   return { cache, result, deactivate };
 }
diff --git a/packages/babel-core/src/config/helpers/environment.js b/packages/babel-core/src/config/helpers/environment.js
index eaa95de791..06bd33484a 100644
--- a/packages/babel-core/src/config/helpers/environment.js
+++ b/packages/babel-core/src/config/helpers/environment.js
@@ -1,7 +1,5 @@
 // @flow
 
 export function getEnv(defaultValue: string = "development"): string {
-  return process.env.BABEL_ENV
-    || process.env.NODE_ENV
-    || defaultValue;
+  return process.env.BABEL_ENV || process.env.NODE_ENV || defaultValue;
 }
diff --git a/packages/babel-core/src/config/index.js b/packages/babel-core/src/config/index.js
index d0a6030d75..f00fd0e924 100644
--- a/packages/babel-core/src/config/index.js
+++ b/packages/babel-core/src/config/index.js
@@ -5,13 +5,13 @@ import manageOptions from "./option-manager";
 
 export type ResolvedConfig = {
   options: Object,
-  passes: Array<Array<[ Plugin, ?{} ]>>,
+  passes: Array<Array<[Plugin, ?{}]>>,
 };
 
 /**
  * Standard API for loading Babel configuration data. Not for public consumption.
  */
-export default function loadConfig(opts: mixed): ResolvedConfig|null {
+export default function loadConfig(opts: mixed): ResolvedConfig | null {
   if (opts != null && typeof opts !== "object") {
     throw new Error("Babel options must be an object, null, or undefined");
   }
diff --git a/packages/babel-core/src/config/loading/files/configuration.js b/packages/babel-core/src/config/loading/files/configuration.js
index 3d762ff8e3..73ce1565d4 100644
--- a/packages/babel-core/src/config/loading/files/configuration.js
+++ b/packages/babel-core/src/config/loading/files/configuration.js
@@ -41,13 +41,16 @@ export function findConfigs(dirname: string): Array<ConfigFile> {
         BABELRC_FILENAME,
         BABELRC_JS_FILENAME,
         PACKAGE_FILENAME,
-      ].reduce((previousConfig: ConfigFile|null, name) => {
+      ].reduce((previousConfig: ConfigFile | null, name) => {
         const filepath = path.join(loc, name);
         const config = readConfig(filepath);
 
         if (config && previousConfig) {
-          throw new Error(`Multiple configuration files found. Please remove one:\n- ${
-            path.basename(previousConfig.filepath)}\n- ${name}\nfrom ${loc}`);
+          throw new Error(
+            `Multiple configuration files found. Please remove one:\n- ${path.basename(
+              previousConfig.filepath,
+            )}\n- ${name}\nfrom ${loc}`,
+          );
         }
 
         return config || previousConfig;
@@ -73,7 +76,9 @@ export function loadConfig(name: string, dirname: string): ConfigFile {
   const filepath = resolve.sync(name, { basedir: dirname });
 
   const conf = readConfig(filepath);
-  if (!conf) throw new Error(`Config file ${filepath} contains no configuration data`);
+  if (!conf) {
+    throw new Error(`Config file ${filepath} contains no configuration data`);
+  }
 
   return conf;
 }
@@ -83,7 +88,9 @@ export function loadConfig(name: string, dirname: string): ConfigFile {
  * throw if there are parsing errors while loading a config.
  */
 function readConfig(filepath) {
-  return (path.extname(filepath) === ".js") ? readConfigJS(filepath) : readConfigFile(filepath);
+  return path.extname(filepath) === ".js"
+    ? readConfigJS(filepath)
+    : readConfigFile(filepath);
 }
 
 const readConfigJS = makeStrongCache((filepath, cache) => {
@@ -96,7 +103,10 @@ const readConfigJS = makeStrongCache((filepath, cache) => {
   try {
     // $FlowIssue
     const configModule = (require(filepath): mixed);
-    options = configModule && configModule.__esModule ? (configModule.default || undefined) : configModule;
+    options =
+      configModule && configModule.__esModule
+        ? configModule.default || undefined
+        : configModule;
   } catch (err) {
     err.message = `${filepath}: Error while loading config - ${err.message}`;
     throw err;
@@ -113,7 +123,9 @@ const readConfigJS = makeStrongCache((filepath, cache) => {
   }
 
   if (!options || typeof options !== "object" || Array.isArray(options)) {
-    throw new Error(`${filepath}: Configuration should be an exported JavaScript object.`);
+    throw new Error(
+      `${filepath}: Configuration should be an exported JavaScript object.`,
+    );
   }
 
   return {
@@ -144,8 +156,12 @@ const readConfigFile = makeStaticFileCache((filepath, content) => {
     if (!options) throw new Error(`${filepath}: No config detected`);
   }
 
-  if (typeof options !== "object") throw new Error(`${filepath}: Config returned typeof ${typeof options}`);
-  if (Array.isArray(options)) throw new Error(`${filepath}: Expected config object but found array`);
+  if (typeof options !== "object") {
+    throw new Error(`${filepath}: Config returned typeof ${typeof options}`);
+  }
+  if (Array.isArray(options)) {
+    throw new Error(`${filepath}: Expected config object but found array`);
+  }
 
   return {
     filepath,
@@ -157,8 +173,8 @@ const readConfigFile = makeStaticFileCache((filepath, content) => {
 const readIgnoreConfig = makeStaticFileCache((filepath, content) => {
   const ignore = content
     .split("\n")
-    .map((line) => line.replace(/#(.*?)$/, "").trim())
-    .filter((line) => !!line);
+    .map(line => line.replace(/#(.*?)$/, "").trim())
+    .filter(line => !!line);
 
   return {
     filepath,
@@ -167,7 +183,7 @@ const readIgnoreConfig = makeStaticFileCache((filepath, content) => {
   };
 });
 
-function makeStaticFileCache<T>(fn: (string, string) => T): (string) => T|null {
+function makeStaticFileCache<T>(fn: (string, string) => T): string => T | null {
   return makeStrongCache((filepath, cache) => {
     if (cache.invalidate(() => fileMtime(filepath)) === null) {
       cache.forever();
@@ -178,7 +194,7 @@ function makeStaticFileCache<T>(fn: (string, string) => T): (string) => T|null {
   });
 }
 
-function fileMtime(filepath: string): number|null {
+function fileMtime(filepath: string): number | null {
   try {
     return +fs.statSync(filepath).mtime;
   } catch (e) {
diff --git a/packages/babel-core/src/config/loading/files/index-browser.js b/packages/babel-core/src/config/loading/files/index-browser.js
index 302c2e9c66..79d5325291 100644
--- a/packages/babel-core/src/config/loading/files/index-browser.js
+++ b/packages/babel-core/src/config/loading/files/index-browser.js
@@ -16,27 +16,47 @@ export function loadConfig(name: string, dirname: string): ConfigFile {
 }
 
 // eslint-disable-next-line no-unused-vars
-export function resolvePlugin(name: string, dirname: string): string|null {
+export function resolvePlugin(name: string, dirname: string): string | null {
   return null;
 }
 
 // eslint-disable-next-line no-unused-vars
-export function resolvePreset(name: string, dirname: string): string|null {
+export function resolvePreset(name: string, dirname: string): string | null {
   return null;
 }
 
-export function loadPlugin(name: string, dirname: string): { filepath: string, value: mixed } {
-  throw new Error(`Cannot load plugin ${name} relative to ${dirname} in a browser`);
+export function loadPlugin(
+  name: string,
+  dirname: string,
+): { filepath: string, value: mixed } {
+  throw new Error(
+    `Cannot load plugin ${name} relative to ${dirname} in a browser`,
+  );
 }
 
-export function loadPreset(name: string, dirname: string): { filepath: string, value: mixed } {
-  throw new Error(`Cannot load preset ${name} relative to ${dirname} in a browser`);
+export function loadPreset(
+  name: string,
+  dirname: string,
+): { filepath: string, value: mixed } {
+  throw new Error(
+    `Cannot load preset ${name} relative to ${dirname} in a browser`,
+  );
 }
 
-export function loadParser(name: string, dirname: string): { filepath: string, value: Function } {
-  throw new Error(`Cannot load parser ${name} relative to ${dirname} in a browser`);
+export function loadParser(
+  name: string,
+  dirname: string,
+): { filepath: string, value: Function } {
+  throw new Error(
+    `Cannot load parser ${name} relative to ${dirname} in a browser`,
+  );
 }
 
-export function loadGenerator(name: string, dirname: string): { filepath: string, value: Function } {
-  throw new Error(`Cannot load generator ${name} relative to ${dirname} in a browser`);
+export function loadGenerator(
+  name: string,
+  dirname: string,
+): { filepath: string, value: Function } {
+  throw new Error(
+    `Cannot load generator ${name} relative to ${dirname} in a browser`,
+  );
 }
diff --git a/packages/babel-core/src/config/loading/files/index.js b/packages/babel-core/src/config/loading/files/index.js
index f26999328e..c7e61ad469 100644
--- a/packages/babel-core/src/config/loading/files/index.js
+++ b/packages/babel-core/src/config/loading/files/index.js
@@ -5,7 +5,7 @@ import typeof * as indexType from "./index";
 
 // Kind of gross, but essentially asserting that the exports of this module are the same as the
 // exports of index-browser, since this file may be replaced at bundle time with index-browser.
-((({}: any) : $Exact<indexBrowserType>): $Exact<indexType>);
+((({}: any): $Exact<indexBrowserType>): $Exact<indexType>);
 
 export * from "./configuration";
 export * from "./plugins";
diff --git a/packages/babel-core/src/config/loading/files/plugins.js b/packages/babel-core/src/config/loading/files/plugins.js
index 7828e90d02..ff65ae8f56 100644
--- a/packages/babel-core/src/config/loading/files/plugins.js
+++ b/packages/babel-core/src/config/loading/files/plugins.js
@@ -15,17 +15,22 @@ const BABEL_PRESET_ORG_RE = /^(@babel[/\/])(?!preset-|[^/\/]+[/\/])/;
 const OTHER_PLUGIN_ORG_RE = /^(@(?!babel[/\/])[^/\/]+[/\/])(?!babel-plugin-|[^/\/]+[/\/])/;
 const OTHER_PRESET_ORG_RE = /^(@(?!babel[/\/])[^/\/]+[/\/])(?!babel-preset-|[^/\/]+[/\/])/;
 
-export function resolvePlugin(name: string, dirname: string): string|null {
+export function resolvePlugin(name: string, dirname: string): string | null {
   return resolveStandardizedName("plugin", name, dirname);
 }
 
-export function resolvePreset(name: string, dirname: string): string|null {
+export function resolvePreset(name: string, dirname: string): string | null {
   return resolveStandardizedName("preset", name, dirname);
 }
 
-export function loadPlugin(name: string, dirname: string): { filepath: string, value: mixed } {
+export function loadPlugin(
+  name: string,
+  dirname: string,
+): { filepath: string, value: mixed } {
   const filepath = resolvePlugin(name, dirname);
-  if (!filepath) throw new Error(`Plugin ${name} not found relative to ${dirname}`);
+  if (!filepath) {
+    throw new Error(`Plugin ${name} not found relative to ${dirname}`);
+  }
 
   return {
     filepath,
@@ -33,9 +38,14 @@ export function loadPlugin(name: string, dirname: string): { filepath: string, v
   };
 }
 
-export function loadPreset(name: string, dirname: string): { filepath: string, value: mixed } {
+export function loadPreset(
+  name: string,
+  dirname: string,
+): { filepath: string, value: mixed } {
   const filepath = resolvePreset(name, dirname);
-  if (!filepath) throw new Error(`Preset ${name} not found relative to ${dirname}`);
+  if (!filepath) {
+    throw new Error(`Preset ${name} not found relative to ${dirname}`);
+  }
 
   return {
     filepath,
@@ -43,16 +53,23 @@ export function loadPreset(name: string, dirname: string): { filepath: string, v
   };
 }
 
-export function loadParser(name: string, dirname: string): { filepath: string, value: Function } {
+export function loadParser(
+  name: string,
+  dirname: string,
+): { filepath: string, value: Function } {
   const filepath = resolve.sync(name, { basedir: dirname });
 
   const mod = requireModule(filepath);
 
   if (!mod) {
-    throw new Error(`Parser ${name} relative to ${dirname} does not export an object`);
+    throw new Error(
+      `Parser ${name} relative to ${dirname} does not export an object`,
+    );
   }
   if (typeof mod.parse !== "function") {
-    throw new Error(`Parser ${name} relative to ${dirname} does not export a .parse function`);
+    throw new Error(
+      `Parser ${name} relative to ${dirname} does not export a .parse function`,
+    );
   }
 
   return {
@@ -61,16 +78,23 @@ export function loadParser(name: string, dirname: string): { filepath: string, v
   };
 }
 
-export function loadGenerator(name: string, dirname: string): { filepath: string, value: Function } {
+export function loadGenerator(
+  name: string,
+  dirname: string,
+): { filepath: string, value: Function } {
   const filepath = resolve.sync(name, { basedir: dirname });
 
   const mod = requireModule(filepath);
 
   if (!mod) {
-    throw new Error(`Generator ${name} relative to ${dirname} does not export an object`);
+    throw new Error(
+      `Generator ${name} relative to ${dirname} does not export an object`,
+    );
   }
   if (typeof mod.print !== "function") {
-    throw new Error(`Generator ${name} relative to ${dirname} does not export a .print function`);
+    throw new Error(
+      `Generator ${name} relative to ${dirname} does not export a .print function`,
+    );
   }
 
   return {
@@ -79,24 +103,39 @@ export function loadGenerator(name: string, dirname: string): { filepath: string
   };
 }
 
-function standardizeName(type: "plugin"|"preset", name: string) {
+function standardizeName(type: "plugin" | "preset", name: string) {
   // Let absolute and relative paths through.
   if (path.isAbsolute(name)) return name;
 
   const isPreset = type === "preset";
 
-  return name
-    // foo -> babel-preset-foo
-    .replace(isPreset ? BABEL_PRESET_PREFIX_RE : BABEL_PLUGIN_PREFIX_RE, `babel-${type}-`)
-    // @babel/es2015 -> @babel/preset-es2015
-    .replace(isPreset ? BABEL_PRESET_ORG_RE : BABEL_PLUGIN_ORG_RE, `$1${type}-`)
-    // @foo/mypreset -> @foo/babel-preset-mypreset
-    .replace(isPreset ? OTHER_PRESET_ORG_RE : OTHER_PLUGIN_ORG_RE, `$1babel-${type}-`)
-    // module:mypreset -> mypreset
-    .replace(EXACT_RE, "");
+  return (
+    name
+      // foo -> babel-preset-foo
+      .replace(
+        isPreset ? BABEL_PRESET_PREFIX_RE : BABEL_PLUGIN_PREFIX_RE,
+        `babel-${type}-`,
+      )
+      // @babel/es2015 -> @babel/preset-es2015
+      .replace(
+        isPreset ? BABEL_PRESET_ORG_RE : BABEL_PLUGIN_ORG_RE,
+        `$1${type}-`,
+      )
+      // @foo/mypreset -> @foo/babel-preset-mypreset
+      .replace(
+        isPreset ? OTHER_PRESET_ORG_RE : OTHER_PLUGIN_ORG_RE,
+        `$1babel-${type}-`,
+      )
+      // module:mypreset -> mypreset
+      .replace(EXACT_RE, "")
+  );
 }
 
-function resolveStandardizedName(type: "plugin"|"preset", name: string, dirname: string = process.cwd()) {
+function resolveStandardizedName(
+  type: "plugin" | "preset",
+  name: string,
+  dirname: string = process.cwd(),
+) {
   const standardizedName = standardizeName(type, name);
 
   try {
@@ -109,7 +148,7 @@ function resolveStandardizedName(type: "plugin"|"preset", name: string, dirname:
       try {
         resolve.sync(name, { basedir: dirname });
         resolvedOriginal = true;
-      } catch (e2) { }
+      } catch (e2) {}
 
       if (resolvedOriginal) {
         // eslint-disable-next-line max-len
@@ -119,9 +158,11 @@ function resolveStandardizedName(type: "plugin"|"preset", name: string, dirname:
 
     let resolvedBabel = false;
     try {
-      resolve.sync(standardizeName(type, "@babel/" + name), { basedir: dirname });
+      resolve.sync(standardizeName(type, "@babel/" + name), {
+        basedir: dirname,
+      });
       resolvedBabel = true;
-    } catch (e2) { }
+    } catch (e2) {}
 
     if (resolvedBabel) {
       // eslint-disable-next-line max-len
@@ -133,7 +174,7 @@ function resolveStandardizedName(type: "plugin"|"preset", name: string, dirname:
     try {
       resolve.sync(standardizeName(oppositeType, name), { basedir: dirname });
       resolvedOppositeType = true;
-    } catch (e2) { }
+    } catch (e2) {}
 
     if (resolvedOppositeType) {
       // eslint-disable-next-line max-len
diff --git a/packages/babel-core/src/config/option-manager.js b/packages/babel-core/src/config/option-manager.js
index a5cfc63bbd..3d50264923 100644
--- a/packages/babel-core/src/config/option-manager.js
+++ b/packages/babel-core/src/config/option-manager.js
@@ -11,14 +11,19 @@ import path from "path";
 import traverse from "babel-traverse";
 import clone from "lodash/clone";
 
-import { loadPlugin, loadPreset, loadParser, loadGenerator } from "./loading/files";
+import {
+  loadPlugin,
+  loadPreset,
+  loadParser,
+  loadGenerator,
+} from "./loading/files";
 
 type MergeOptions = {
-  +type: "arguments"|"options"|"preset",
+  +type: "arguments" | "options" | "preset",
   options: {},
   alias: string,
   loc: string,
-  dirname: string
+  dirname: string,
 };
 
 const optionNames = new Set([
@@ -74,8 +79,8 @@ const ALLOWED_PLUGIN_KEYS = new Set([
 
 export default function manageOptions(opts: {}): {
   options: Object,
-  passes: Array<Array<[ Plugin, ?{} ]>>,
-}|null {
+  passes: Array<Array<[Plugin, ?{}]>>,
+} | null {
   return new OptionManager().init(opts);
 }
 
@@ -100,9 +105,12 @@ class OptionManager {
   mergeOptions(config: MergeOptions, pass?: Array<[Plugin, ?{}]>) {
     const result = loadConfig(config);
 
-    const plugins = result.plugins.map((descriptor) => loadPluginDescriptor(descriptor));
-    const presets = result.presets.map((descriptor) => loadPresetDescriptor(descriptor));
-
+    const plugins = result.plugins.map(descriptor =>
+      loadPluginDescriptor(descriptor),
+    );
+    const presets = result.presets.map(descriptor =>
+      loadPresetDescriptor(descriptor),
+    );
 
     if (
       config.options.passPerPreset != null &&
@@ -148,7 +156,8 @@ class OptionManager {
       // There are a few case where thrown errors will try to annotate themselves multiple times, so
       // to keep things simple we just bail out if re-wrapping the message.
       if (!/^\[BABEL\]/.test(e.message)) {
-        const filename = typeof opts.filename === "string" ? opts.filename : null;
+        const filename =
+          typeof opts.filename === "string" ? opts.filename : null;
         e.message = `[BABEL] ${filename || "unknown"}: ${e.message}`;
       }
 
@@ -160,9 +169,10 @@ class OptionManager {
     // Tack the passes onto the object itself so that, if this object is passed back to Babel a second time,
     // it will be in the right structure to not change behavior.
     opts.plugins = this.passes[0];
-    opts.presets = this.passes.slice(1)
-      .filter((plugins) => plugins.length > 0)
-      .map((plugins) => ({ plugins }));
+    opts.presets = this.passes
+      .slice(1)
+      .filter(plugins => plugins.length > 0)
+      .map(plugins => ({ plugins }));
 
     if (opts.inputSourceMap) {
       opts.sourceMaps = true;
@@ -199,7 +209,7 @@ class OptionManager {
 }
 
 type BasicDescriptor = {
-  value: {}|Function,
+  value: {} | Function,
   options: ?{},
   dirname: string,
   alias: string,
@@ -209,19 +219,28 @@ type BasicDescriptor = {
 /**
  * Load and validate the given config into a set of options, plugins, and presets.
  */
-function loadConfig(config): {
+function loadConfig(
+  config,
+): {
   options: {},
   plugins: Array<BasicDescriptor>,
   presets: Array<BasicDescriptor>,
 } {
   const options = normalizeOptions(config);
 
-  if (config.options.plugins != null && !Array.isArray(config.options.plugins)) {
+  if (
+    config.options.plugins != null &&
+    !Array.isArray(config.options.plugins)
+  ) {
     throw new Error(".plugins should be an array, null, or undefined");
   }
 
   const plugins = (config.options.plugins || []).map((plugin, index) => {
-    const { filepath, value, options } = normalizePair(plugin, loadPlugin, config.dirname);
+    const { filepath, value, options } = normalizePair(
+      plugin,
+      loadPlugin,
+      config.dirname,
+    );
 
     return {
       alias: filepath || `${config.loc}$${index}`,
@@ -232,12 +251,19 @@ function loadConfig(config): {
     };
   });
 
-  if (config.options.presets != null && !Array.isArray(config.options.presets)) {
+  if (
+    config.options.presets != null &&
+    !Array.isArray(config.options.presets)
+  ) {
     throw new Error(".presets should be an array, null, or undefined");
   }
 
   const presets = (config.options.presets || []).map((preset, index) => {
-    const { filepath, value, options } = normalizePair(preset, loadPreset, config.dirname);
+    const { filepath, value, options } = normalizePair(
+      preset,
+      loadPreset,
+      config.dirname,
+    );
 
     return {
       alias: filepath || `${config.loc}$${index}`,
@@ -255,7 +281,9 @@ function loadConfig(config): {
  * Load a generic plugin/preset from the given descriptor loaded from the config object.
  */
 function loadDescriptor(descriptor, skipOptions) {
-  if (typeof descriptor.value !== "function") return { value: descriptor.value, descriptor };
+  if (typeof descriptor.value !== "function") {
+    return { value: descriptor.value, descriptor };
+  }
 
   const { value, options } = descriptor;
   let item;
@@ -266,7 +294,9 @@ function loadDescriptor(descriptor, skipOptions) {
       item = value(context, options, { dirname: descriptor.dirname });
     }
   } catch (e) {
-    if (descriptor.alias) e.message += ` (While processing: ${JSON.stringify(descriptor.alias)})`;
+    if (descriptor.alias) {
+      e.message += ` (While processing: ${JSON.stringify(descriptor.alias)})`;
+    }
     throw e;
   }
 
@@ -282,26 +312,37 @@ function loadDescriptor(descriptor, skipOptions) {
  */
 const PLUGIN_CACHE = new WeakMap();
 function loadPluginDescriptor(descriptor) {
-  if (descriptor.value instanceof Plugin) return [ descriptor.value, descriptor.options ];
+  if (descriptor.value instanceof Plugin) {
+    return [descriptor.value, descriptor.options];
+  }
 
   let result = PLUGIN_CACHE.get(descriptor.value);
   if (!result) {
-    result = instantiatePlugin(loadDescriptor(descriptor, true /* skipOptions */));
+    result = instantiatePlugin(
+      loadDescriptor(descriptor, true /* skipOptions */),
+    );
     PLUGIN_CACHE.set(descriptor.value, result);
   }
 
-  return [ result, descriptor.options];
+  return [result, descriptor.options];
 }
 
 function instantiatePlugin({ value: pluginObj, descriptor }) {
-  Object.keys(pluginObj).forEach((key) => {
+  Object.keys(pluginObj).forEach(key => {
     if (!ALLOWED_PLUGIN_KEYS.has(key)) {
-      throw new Error(messages.get("pluginInvalidProperty", descriptor.alias, key));
+      throw new Error(
+        messages.get("pluginInvalidProperty", descriptor.alias, key),
+      );
     }
   });
-  if (pluginObj.visitor && (pluginObj.visitor.enter || pluginObj.visitor.exit)) {
-    throw new Error("Plugins aren't allowed to specify catch-all enter/exit handlers. " +
-      "Please target individual nodes.");
+  if (
+    pluginObj.visitor &&
+    (pluginObj.visitor.enter || pluginObj.visitor.exit)
+  ) {
+    throw new Error(
+      "Plugins aren't allowed to specify catch-all enter/exit handlers. " +
+        "Please target individual nodes.",
+    );
   }
 
   const plugin = Object.assign({}, pluginObj, {
@@ -325,8 +366,14 @@ function instantiatePlugin({ value: pluginObj, descriptor }) {
 
     plugin.pre = chain(inherits.pre, plugin.pre);
     plugin.post = chain(inherits.post, plugin.post);
-    plugin.manipulateOptions = chain(inherits.manipulateOptions, plugin.manipulateOptions);
-    plugin.visitor = traverse.visitors.merge([inherits.visitor, plugin.visitor]);
+    plugin.manipulateOptions = chain(
+      inherits.manipulateOptions,
+      plugin.manipulateOptions,
+    );
+    plugin.visitor = traverse.visitors.merge([
+      inherits.visitor,
+      plugin.visitor,
+    ]);
   }
 
   return new Plugin(plugin, descriptor.alias);
@@ -371,10 +418,18 @@ function normalizeOptions(config) {
   }
 
   if (type === "preset") {
-    if (options.only !== undefined) throw new Error(`${alias}.only is not supported in a preset`);
-    if (options.ignore !== undefined) throw new Error(`${alias}.ignore is not supported in a preset`);
-    if (options.extends !== undefined) throw new Error(`${alias}.extends is not supported in a preset`);
-    if (options.env !== undefined) throw new Error(`${alias}.env is not supported in a preset`);
+    if (options.only !== undefined) {
+      throw new Error(`${alias}.only is not supported in a preset`);
+    }
+    if (options.ignore !== undefined) {
+      throw new Error(`${alias}.ignore is not supported in a preset`);
+    }
+    if (options.extends !== undefined) {
+      throw new Error(`${alias}.extends is not supported in a preset`);
+    }
+    if (options.env !== undefined) {
+      throw new Error(`${alias}.env is not supported in a preset`);
+    }
   }
 
   if (options.sourceMap !== undefined) {
@@ -390,7 +445,10 @@ function normalizeOptions(config) {
     // check for an unknown option
     if (!optionNames.has(key)) {
       if (removed[key]) {
-        throw new ReferenceError(`Using removed Babel 5 option: ${alias}.${key} - ${removed[key].message}`);
+        throw new ReferenceError(
+          `Using removed Babel 5 option: ${alias}.${key} - ${removed[key]
+            .message}`,
+        );
       } else {
         // eslint-disable-next-line max-len
         const unknownOptErr = `Unknown option: ${alias}.${key}. Check out http://babeljs.io/docs/usage/options/ for more information about options.`;
@@ -402,12 +460,21 @@ function normalizeOptions(config) {
 
   if (options.parserOpts && typeof options.parserOpts.parser === "string") {
     options.parserOpts = Object.assign({}, options.parserOpts);
-    options.parserOpts.parser = loadParser(options.parserOpts.parser, config.dirname).value;
+    options.parserOpts.parser = loadParser(
+      options.parserOpts.parser,
+      config.dirname,
+    ).value;
   }
 
-  if (options.generatorOpts && typeof options.generatorOpts.generator === "string") {
+  if (
+    options.generatorOpts &&
+    typeof options.generatorOpts.generator === "string"
+  ) {
     options.generatorOpts = Object.assign({}, options.generatorOpts);
-    options.generatorOpts.generator = loadGenerator(options.generatorOpts.generator, config.dirname).value;
+    options.generatorOpts.generator = loadGenerator(
+      options.generatorOpts.generator,
+      config.dirname,
+    ).value;
   }
 
   delete options.passPerPreset;
@@ -420,16 +487,22 @@ function normalizeOptions(config) {
 /**
  * Given a plugin/preset item, resolve it into a standard format.
  */
-function normalizePair(pair: mixed, resolver, dirname): {
-  filepath: string|null,
-  value: {}|Function,
+function normalizePair(
+  pair: mixed,
+  resolver,
+  dirname,
+): {
+  filepath: string | null,
+  value: {} | Function,
   options: ?{},
 } {
   let options;
   let value = pair;
   if (Array.isArray(pair)) {
     if (pair.length > 2) {
-      throw new Error(`Unexpected extra options ${JSON.stringify(pair.slice(2))}.`);
+      throw new Error(
+        `Unexpected extra options ${JSON.stringify(pair.slice(2))}.`,
+      );
     }
 
     [value, options] = pair;
@@ -437,10 +510,7 @@ function normalizePair(pair: mixed, resolver, dirname): {
 
   let filepath = null;
   if (typeof value === "string") {
-    ({
-      filepath,
-      value,
-    } = resolver(value, dirname));
+    ({ filepath, value } = resolver(value, dirname));
   }
 
   if (!value) {
@@ -456,11 +526,15 @@ function normalizePair(pair: mixed, resolver, dirname): {
   }
 
   if (typeof value !== "object" && typeof value !== "function") {
-    throw new Error(`Unsupported format: ${typeof value}. Expected an object or a function.`);
+    throw new Error(
+      `Unsupported format: ${typeof value}. Expected an object or a function.`,
+    );
   }
 
   if (options != null && typeof options !== "object") {
-    throw new Error("Plugin/Preset options must be an object, null, or undefined");
+    throw new Error(
+      "Plugin/Preset options must be an object, null, or undefined",
+    );
   }
 
   return { filepath, value, options };
diff --git a/packages/babel-core/src/config/plugin.js b/packages/babel-core/src/config/plugin.js
index 7e6036ec0f..84b3701061 100644
--- a/packages/babel-core/src/config/plugin.js
+++ b/packages/babel-core/src/config/plugin.js
@@ -5,8 +5,13 @@ export default class Plugin {
     if (plugin.name != null && typeof plugin.name !== "string") {
       throw new Error("Plugin .name must be a string, null, or undefined");
     }
-    if (plugin.manipulateOptions != null && typeof plugin.manipulateOptions !== "function") {
-      throw new Error("Plugin .manipulateOptions must be a function, null, or undefined");
+    if (
+      plugin.manipulateOptions != null &&
+      typeof plugin.manipulateOptions !== "function"
+    ) {
+      throw new Error(
+        "Plugin .manipulateOptions must be a function, null, or undefined",
+      );
     }
     if (plugin.post != null && typeof plugin.post !== "function") {
       throw new Error("Plugin .post must be a function, null, or undefined");
diff --git a/packages/babel-core/src/config/removed.js b/packages/babel-core/src/config/removed.js
index 542f7d1533..751209e8e6 100644
--- a/packages/babel-core/src/config/removed.js
+++ b/packages/babel-core/src/config/removed.js
@@ -2,52 +2,58 @@
 /* eslint max-len: "off" */
 
 export default {
-  "auxiliaryComment": {
-    "message": "Use `auxiliaryCommentBefore` or `auxiliaryCommentAfter`",
+  auxiliaryComment: {
+    message: "Use `auxiliaryCommentBefore` or `auxiliaryCommentAfter`",
   },
-  "blacklist": {
-    "message": "Put the specific transforms you want in the `plugins` option",
+  blacklist: {
+    message: "Put the specific transforms you want in the `plugins` option",
   },
-  "breakConfig": {
-    "message": "This is not a necessary option in Babel 6",
+  breakConfig: {
+    message: "This is not a necessary option in Babel 6",
   },
-  "experimental": {
-    "message": "Put the specific transforms you want in the `plugins` option",
+  experimental: {
+    message: "Put the specific transforms you want in the `plugins` option",
   },
-  "externalHelpers": {
-    "message": "Use the `external-helpers` plugin instead. Check out http://babeljs.io/docs/plugins/external-helpers/",
+  externalHelpers: {
+    message:
+      "Use the `external-helpers` plugin instead. Check out http://babeljs.io/docs/plugins/external-helpers/",
   },
-  "extra": {
-    "message": "",
+  extra: {
+    message: "",
   },
-  "jsxPragma": {
-    "message": "use the `pragma` option in the `react-jsx` plugin . Check out http://babeljs.io/docs/plugins/transform-react-jsx/",
+  jsxPragma: {
+    message:
+      "use the `pragma` option in the `react-jsx` plugin . Check out http://babeljs.io/docs/plugins/transform-react-jsx/",
   },
   // "keepModuleIdExtensions": {
   //   "message": ""
   // },
-  "loose": {
-    "message": "Specify the `loose` option for the relevant plugin you are using or use a preset that sets the option.",
+  loose: {
+    message:
+      "Specify the `loose` option for the relevant plugin you are using or use a preset that sets the option.",
   },
-  "metadataUsedHelpers": {
-    "message": "Not required anymore as this is enabled by default",
+  metadataUsedHelpers: {
+    message: "Not required anymore as this is enabled by default",
   },
-  "modules": {
-    "message": "Use the corresponding module transform plugin in the `plugins` option. Check out http://babeljs.io/docs/plugins/#modules",
+  modules: {
+    message:
+      "Use the corresponding module transform plugin in the `plugins` option. Check out http://babeljs.io/docs/plugins/#modules",
   },
-  "nonStandard": {
-    "message": "Use the `react-jsx` and `flow-strip-types` plugins to support JSX and Flow. Also check out the react preset http://babeljs.io/docs/plugins/preset-react/",
+  nonStandard: {
+    message:
+      "Use the `react-jsx` and `flow-strip-types` plugins to support JSX and Flow. Also check out the react preset http://babeljs.io/docs/plugins/preset-react/",
   },
-  "optional": {
-    "message": "Put the specific transforms you want in the `plugins` option",
+  optional: {
+    message: "Put the specific transforms you want in the `plugins` option",
   },
-  "sourceMapName": {
-    "message": "Use the `sourceMapTarget` option",
+  sourceMapName: {
+    message: "Use the `sourceMapTarget` option",
   },
-  "stage": {
-    "message": "Check out the corresponding stage-x presets http://babeljs.io/docs/plugins/#presets",
+  stage: {
+    message:
+      "Check out the corresponding stage-x presets http://babeljs.io/docs/plugins/#presets",
   },
-  "whitelist": {
-    "message": "Put the specific transforms you want in the `plugins` option",
+  whitelist: {
+    message: "Put the specific transforms you want in the `plugins` option",
   },
 };
diff --git a/packages/babel-core/src/index.js b/packages/babel-core/src/index.js
index 918929f9bc..35e8e5c77f 100644
--- a/packages/babel-core/src/index.js
+++ b/packages/babel-core/src/index.js
@@ -12,7 +12,7 @@ export template from "babel-template";
 
 import loadConfig from "./config";
 
-export function loadOptions(opts): Object|null {
+export function loadOptions(opts): Object | null {
   const config = loadConfig(opts);
 
   return config ? config.options : null;
@@ -41,4 +41,10 @@ export {
  * Recommended set of compilable extensions. Not used in babel-core directly, but meant as
  * as an easy source for tooling making use of babel-core.
  */
-export const DEFAULT_EXTENSIONS = Object.freeze([".js", ".jsx", ".es6", ".es", ".mjs"]);
+export const DEFAULT_EXTENSIONS = Object.freeze([
+  ".js",
+  ".jsx",
+  ".es6",
+  ".es",
+  ".mjs",
+]);
diff --git a/packages/babel-core/src/tools/build-external-helpers.js b/packages/babel-core/src/tools/build-external-helpers.js
index 75a00f0fff..7d0a311d36 100644
--- a/packages/babel-core/src/tools/build-external-helpers.js
+++ b/packages/babel-core/src/tools/build-external-helpers.js
@@ -20,17 +20,29 @@ const buildUmdWrapper = template(`
 
 function buildGlobal(namespace, builder) {
   const body = [];
-  const container = t.functionExpression(null, [t.identifier("global")], t.blockStatement(body));
+  const container = t.functionExpression(
+    null,
+    [t.identifier("global")],
+    t.blockStatement(body),
+  );
   const tree = t.program([
-    t.expressionStatement(t.callExpression(container, [helpers.get("selfGlobal")]))]);
-
-  body.push(t.variableDeclaration("var", [
-    t.variableDeclarator(
-      namespace,
-      t.assignmentExpression("=", t.memberExpression(t.identifier("global"), namespace),
-        t.objectExpression([]))
+    t.expressionStatement(
+      t.callExpression(container, [helpers.get("selfGlobal")]),
     ),
-  ]));
+  ]);
+
+  body.push(
+    t.variableDeclaration("var", [
+      t.variableDeclarator(
+        namespace,
+        t.assignmentExpression(
+          "=",
+          t.memberExpression(t.identifier("global"), namespace),
+          t.objectExpression([]),
+        ),
+      ),
+    ]),
+  );
 
   builder(body);
 
@@ -39,9 +51,11 @@ function buildGlobal(namespace, builder) {
 
 function buildUmd(namespace, builder) {
   const body = [];
-  body.push(t.variableDeclaration("var", [
-    t.variableDeclarator(namespace, t.identifier("global")),
-  ]));
+  body.push(
+    t.variableDeclaration("var", [
+      t.variableDeclarator(namespace, t.identifier("global")),
+    ]),
+  );
 
   builder(body);
 
@@ -51,7 +65,7 @@ function buildUmd(namespace, builder) {
       BROWSER_ARGUMENTS: t.assignmentExpression(
         "=",
         t.memberExpression(t.identifier("root"), namespace),
-        t.objectExpression([])
+        t.objectExpression([]),
       ),
       COMMON_ARGUMENTS: t.identifier("exports"),
       AMD_ARGUMENTS: t.arrayExpression([t.stringLiteral("exports")]),
@@ -63,31 +77,39 @@ function buildUmd(namespace, builder) {
 
 function buildVar(namespace, builder) {
   const body = [];
-  body.push(t.variableDeclaration("var", [
-    t.variableDeclarator(namespace, t.objectExpression([])),
-  ]));
+  body.push(
+    t.variableDeclaration("var", [
+      t.variableDeclarator(namespace, t.objectExpression([])),
+    ]),
+  );
   builder(body);
   body.push(t.expressionStatement(namespace));
   return t.program(body);
 }
 
 function buildHelpers(body, namespace, whitelist) {
-  helpers.list.forEach(function (name) {
+  helpers.list.forEach(function(name) {
     if (whitelist && whitelist.indexOf(name) < 0) return;
 
     const key = t.identifier(name);
-    body.push(t.expressionStatement(
-      t.assignmentExpression("=", t.memberExpression(namespace, key), helpers.get(name))
-    ));
+    body.push(
+      t.expressionStatement(
+        t.assignmentExpression(
+          "=",
+          t.memberExpression(namespace, key),
+          helpers.get(name),
+        ),
+      ),
+    );
   });
 }
-export default function (
+export default function(
   whitelist?: Array<string>,
   outputType: "global" | "umd" | "var" = "global",
 ) {
   const namespace = t.identifier("babelHelpers");
 
-  const builder = function (body) {
+  const builder = function(body) {
     return buildHelpers(body, namespace, whitelist);
   };
 
diff --git a/packages/babel-core/src/transformation/file/index.js b/packages/babel-core/src/transformation/file/index.js
index bf5063198f..77fabcb11f 100644
--- a/packages/babel-core/src/transformation/file/index.js
+++ b/packages/babel-core/src/transformation/file/index.js
@@ -45,7 +45,7 @@ export default class File extends Store {
       // passed babel-core's export object, which loads this file, and this 'loadConfig' loading plugins.
       INTERNAL_PLUGINS = loadConfig({
         babelrc: false,
-        plugins: [ blockHoistPlugin ],
+        plugins: [blockHoistPlugin],
       }).passes[0];
     }
 
@@ -61,7 +61,7 @@ export default class File extends Store {
     };
 
     for (const pluginPairs of passes) {
-      for (const [ plugin ] of pluginPairs) {
+      for (const [plugin] of pluginPairs) {
         if (plugin.manipulateOptions) {
           plugin.manipulateOptions(this.opts, this.parserOpts, this);
         }
@@ -150,7 +150,7 @@ export default class File extends Store {
 
     if (opts.sourceRoot != null) {
       // remove sourceRoot from filename
-      const sourceRootRegEx = new RegExp("^" + opts.sourceRoot + "\/?");
+      const sourceRootRegEx = new RegExp("^" + opts.sourceRoot + "/?");
       filenameRelative = filenameRelative.replace(sourceRootRegEx, "");
     }
 
@@ -172,17 +172,25 @@ export default class File extends Store {
 
   resolveModuleSource(source: string): string {
     const resolveModuleSource = this.opts.resolveModuleSource;
-    if (resolveModuleSource) source = resolveModuleSource(source, this.opts.filename);
+    if (resolveModuleSource) {
+      source = resolveModuleSource(source, this.opts.filename);
+    }
     return source;
   }
 
-  addImport(source: string, imported: string, name?: string = imported): Object {
+  addImport(
+    source: string,
+    imported: string,
+    name?: string = imported,
+  ): Object {
     const alias = `${source}:${imported}`;
     let id = this.dynamicImportIds[alias];
 
     if (!id) {
       source = this.resolveModuleSource(source);
-      id = this.dynamicImportIds[alias] = this.scope.generateUidIdentifier(name);
+      id = this.dynamicImportIds[alias] = this.scope.generateUidIdentifier(
+        name,
+      );
 
       const specifiers = [];
 
@@ -222,7 +230,9 @@ export default class File extends Store {
     }
 
     const ref = getHelper(name);
-    const uid = this.declarations[name] = this.scope.generateUidIdentifier(name);
+    const uid = (this.declarations[name] = this.scope.generateUidIdentifier(
+      name,
+    ));
 
     if (t.isFunctionExpression(ref) && !ref.id) {
       ref.body._compact = true;
@@ -257,7 +267,9 @@ export default class File extends Store {
     const declar = this.declarations[name];
     if (declar) return declar;
 
-    const uid = this.declarations[name] = this.scope.generateUidIdentifier("templateObject");
+    const uid = (this.declarations[name] = this.scope.generateUidIdentifier(
+      "templateObject",
+    ));
 
     const helperId = this.addHelper(helperName);
     const init = t.callExpression(helperId, [strings, raw]);
@@ -270,7 +282,11 @@ export default class File extends Store {
     return uid;
   }
 
-  buildCodeFrameError(node: Object, msg: string, Error: typeof Error = SyntaxError): Error {
+  buildCodeFrameError(
+    node: Object,
+    msg: string,
+    Error: typeof Error = SyntaxError,
+  ): Error {
     const loc = node && (node.loc || node._loc);
 
     const err = new Error(msg);
@@ -280,7 +296,8 @@ export default class File extends Store {
     } else {
       traverse(node, errorVisitor, this.scope, err);
 
-      err.message += " (This is an error on an internal node. Probably an internal error";
+      err.message +=
+        " (This is an error on an internal node. Probably an internal error";
 
       if (err.loc) {
         err.message += ". Location has been estimated.";
@@ -308,7 +325,7 @@ export default class File extends Store {
       // single source file to a single output file.
       const source = outputMapConsumer.sources[0];
 
-      inputMapConsumer.eachMapping(function (mapping) {
+      inputMapConsumer.eachMapping(function(mapping) {
         const generatedPosition = outputMapConsumer.generatedPositionFor({
           line: mapping.generatedLine,
           column: mapping.generatedColumn,
@@ -318,10 +335,13 @@ export default class File extends Store {
           mergedGenerator.addMapping({
             source: mapping.source,
 
-            original: mapping.source == null ? null : {
-              line: mapping.originalLine,
-              column: mapping.originalColumn,
-            },
+            original:
+              mapping.source == null
+                ? null
+                : {
+                    line: mapping.originalLine,
+                    column: mapping.originalColumn,
+                  },
 
             generated: generatedPosition,
           });
@@ -385,15 +405,15 @@ export default class File extends Store {
       const passes = [];
       const visitors = [];
 
-      for (const [ plugin, pluginOpts ] of pluginPairs.concat(INTERNAL_PLUGINS)) {
+      for (const [plugin, pluginOpts] of pluginPairs.concat(INTERNAL_PLUGINS)) {
         const pass = new PluginPass(this, plugin.key, pluginOpts);
 
-        passPairs.push([ plugin, pass ]);
+        passPairs.push([plugin, pass]);
         passes.push(pass);
         visitors.push(plugin.visitor);
       }
 
-      for (const [ plugin, pass ] of passPairs) {
+      for (const [plugin, pass] of passPairs) {
         const fn = plugin.pre;
         if (fn) fn.call(pass, this);
       }
@@ -401,16 +421,19 @@ export default class File extends Store {
       debug(this.opts, "Start transform traverse");
 
       // merge all plugin visitors into a single visitor
-      const visitor = traverse.visitors.merge(visitors, passes, this.opts.wrapPluginVisitorMethod);
+      const visitor = traverse.visitors.merge(
+        visitors,
+        passes,
+        this.opts.wrapPluginVisitorMethod,
+      );
       traverse(this.ast, visitor, this.scope);
 
       debug(this.opts, "End transform traverse");
 
-      for (const [ plugin, pass ] of passPairs) {
+      for (const [plugin, pass] of passPairs) {
         const fn = plugin.post;
         if (fn) fn.call(pass, this);
       }
-
     }
 
     return this.generate();
@@ -428,7 +451,7 @@ export default class File extends Store {
         err._babel = true;
       }
 
-      let message = err.message = `${this.opts.filename}: ${err.message}`;
+      let message = (err.message = `${this.opts.filename}: ${err.message}`);
 
       const loc = err.loc;
       if (loc) {
@@ -530,8 +553,11 @@ export default class File extends Store {
 
     debug(this.opts, "Generation start");
 
-    const _result = gen(ast, opts.generatorOpts ? Object.assign(opts, opts.generatorOpts) : opts,
-      this.code);
+    const _result = gen(
+      ast,
+      opts.generatorOpts ? Object.assign(opts, opts.generatorOpts) : opts,
+      this.code,
+    );
     result.code = _result.code;
     result.map = _result.map;
 
diff --git a/packages/babel-core/src/transformation/pipeline.js b/packages/babel-core/src/transformation/pipeline.js
index aafaff2f92..a0b1db373e 100644
--- a/packages/babel-core/src/transformation/pipeline.js
+++ b/packages/babel-core/src/transformation/pipeline.js
@@ -5,7 +5,11 @@ import * as t from "babel-types";
 import File from "./file";
 import loadConfig from "../config";
 
-export function analyse(code: string, opts: Object = {}, visitor?: Object): ?BabelFileMetadata {
+export function analyse(
+  code: string,
+  opts: Object = {},
+  visitor?: Object,
+): ?BabelFileMetadata {
   opts.code = false;
   if (visitor) {
     opts.plugins = opts.plugins || [];
@@ -19,14 +23,18 @@ export function transform(code: string, opts?: Object): BabelFileResult {
   if (config === null) return null;
 
   const file = new File(config);
-  return file.wrap(code, function () {
+  return file.wrap(code, function() {
     file.addCode(code);
     file.parseCode(code);
     return file.transform();
   });
 }
 
-export function transformFromAst(ast: Object, code: string, opts: Object): BabelFileResult {
+export function transformFromAst(
+  ast: Object,
+  code: string,
+  opts: Object,
+): BabelFileResult {
   const config = loadConfig(opts);
   if (config === null) return null;
 
@@ -37,14 +45,18 @@ export function transformFromAst(ast: Object, code: string, opts: Object): Babel
   }
 
   const file = new File(config);
-  return file.wrap(code, function () {
+  return file.wrap(code, function() {
     file.addCode(code);
     file.addAst(ast);
     return file.transform();
   });
 }
 
-export function transformFile(filename: string, opts?: Object, callback: Function) {
+export function transformFile(
+  filename: string,
+  opts?: Object,
+  callback: Function,
+) {
   if (typeof opts === "function") {
     callback = opts;
     opts = {};
@@ -54,13 +66,13 @@ export function transformFile(filename: string, opts?: Object, callback: Functio
   const config = loadConfig(opts);
   if (config === null) return callback(null, null);
 
-  fs.readFile(filename, function (err, code) {
+  fs.readFile(filename, function(err, code) {
     let result;
 
     if (!err) {
       try {
         const file = new File(config);
-        result = file.wrap(code, function () {
+        result = file.wrap(code, function() {
           file.addCode(code);
           file.parseCode(code);
           return file.transform();
@@ -78,7 +90,10 @@ export function transformFile(filename: string, opts?: Object, callback: Functio
   });
 }
 
-export function transformFileSync(filename: string, opts?: Object = {}): string {
+export function transformFileSync(
+  filename: string,
+  opts?: Object = {},
+): string {
   opts.filename = filename;
   const config = loadConfig(opts);
   if (config === null) return null;
@@ -86,7 +101,7 @@ export function transformFileSync(filename: string, opts?: Object = {}): string
   const code = fs.readFileSync(filename, "utf8");
   const file = new File(config);
 
-  return file.wrap(code, function () {
+  return file.wrap(code, function() {
     file.addCode(code);
     file.parseCode(code);
     return file.transform();
diff --git a/packages/babel-core/test/api.js b/packages/babel-core/test/api.js
index 63598ab388..1e8527b96a 100644
--- a/packages/babel-core/test/api.js
+++ b/packages/babel-core/test/api.js
@@ -17,7 +17,7 @@ function assertNotIgnored(result) {
 // shim
 function transformAsync(code, opts) {
   return {
-    then: function (resolve) {
+    then: function(resolve) {
       resolve(babel.transform(code, opts));
     },
   };
@@ -55,11 +55,14 @@ describe("parser and generator options", function() {
   it("experimental syntax", function() {
     const experimental = "var a: number = 1;";
 
-    assert.deepEqual(newTransform(experimental).ast, babel.transform(experimental, {
-      parserOpts: {
-        plugins: ["flow"],
-      },
-    }).ast);
+    assert.deepEqual(
+      newTransform(experimental).ast,
+      babel.transform(experimental, {
+        parserOpts: {
+          plugins: ["flow"],
+        },
+      }).ast,
+    );
     assert.equal(newTransform(experimental).code, experimental);
 
     function newTransformWithPlugins(string) {
@@ -74,126 +77,158 @@ describe("parser and generator options", function() {
       });
     }
 
-    assert.deepEqual(newTransformWithPlugins(experimental).ast, babel.transform(experimental, {
-      parserOpts: {
-        plugins: ["flow"],
-      },
-    }).ast);
+    assert.deepEqual(
+      newTransformWithPlugins(experimental).ast,
+      babel.transform(experimental, {
+        parserOpts: {
+          plugins: ["flow"],
+        },
+      }).ast,
+    );
     assert.equal(newTransformWithPlugins(experimental).code, experimental);
   });
 
   it("other options", function() {
     const experimental = "if (true) {\n  import a from 'a';\n}";
 
-    assert.notEqual(newTransform(experimental).ast, babel.transform(experimental, {
-      parserOpts: {
-        allowImportExportEverywhere: true,
-      },
-    }).ast);
+    assert.notEqual(
+      newTransform(experimental).ast,
+      babel.transform(experimental, {
+        parserOpts: {
+          allowImportExportEverywhere: true,
+        },
+      }).ast,
+    );
     assert.equal(newTransform(experimental).code, experimental);
   });
 });
 
-describe("api", function () {
-  it("analyze", function () {
+describe("api", function() {
+  it("analyze", function() {
     assert.equal(babel.analyse("foobar;").marked.length, 0);
 
-    assert.equal(babel.analyse("foobar;", {
-      plugins: [new Plugin({
-        visitor: {
-          Program: function (path) {
+    assert.equal(
+      babel.analyse("foobar;", {
+        plugins: [
+          new Plugin({
+            visitor: {
+              Program: function(path) {
+                path.mark("category", "foobar");
+              },
+            },
+          }),
+        ],
+      }).marked[0].message,
+      "foobar",
+    );
+
+    assert.equal(
+      babel.analyse(
+        "foobar;",
+        {},
+        {
+          Program: function(path) {
             path.mark("category", "foobar");
           },
         },
-      })],
-    }).marked[0].message, "foobar");
-
-    assert.equal(babel.analyse("foobar;", {}, {
-      Program: function (path) {
-        path.mark("category", "foobar");
-      },
-    }).marked[0].message, "foobar");
-  });
-
-  it("exposes the resolvePlugin method", function() {
-    assert.throws(() => babel.resolvePlugin("nonexistent-plugin"),
-      /Cannot find module 'babel-plugin-nonexistent-plugin'/);
-  });
-
-  it("exposes the resolvePreset method", function() {
-    assert.throws(() => babel.resolvePreset("nonexistent-preset"),
-      /Cannot find module 'babel-preset-nonexistent-preset'/);
-  });
-
-  it("transformFile", function (done) {
-    babel.transformFile(__dirname + "/fixtures/api/file.js", {
-      babelrc: false,
-    }, function (err, res) {
-      if (err) return done(err);
-      assert.equal(res.code, "foo();");
-      done();
-    });
-  });
-
-  it("transformFileSync", function () {
-    assert.equal(babel.transformFileSync(__dirname + "/fixtures/api/file.js", {
-      babelrc: false,
-    }).code, "foo();");
-  });
-
-  it("options throw on falsy true", function () {
-    return assert.throws(
-      function () {
-        babel.transform("", {
-          plugins: [__dirname + "/../../babel-plugin-syntax-jsx", false],
-        });
-      },
-      /Error: \[BABEL\] unknown: Unexpected falsy value: false/
+      ).marked[0].message,
+      "foobar",
     );
   });
 
-  it("options merge backwards", function () {
+  it("exposes the resolvePlugin method", function() {
+    assert.throws(
+      () => babel.resolvePlugin("nonexistent-plugin"),
+      /Cannot find module 'babel-plugin-nonexistent-plugin'/,
+    );
+  });
+
+  it("exposes the resolvePreset method", function() {
+    assert.throws(
+      () => babel.resolvePreset("nonexistent-preset"),
+      /Cannot find module 'babel-preset-nonexistent-preset'/,
+    );
+  });
+
+  it("transformFile", function(done) {
+    babel.transformFile(
+      __dirname + "/fixtures/api/file.js",
+      {
+        babelrc: false,
+      },
+      function(err, res) {
+        if (err) return done(err);
+        assert.equal(res.code, "foo();");
+        done();
+      },
+    );
+  });
+
+  it("transformFileSync", function() {
+    assert.equal(
+      babel.transformFileSync(__dirname + "/fixtures/api/file.js", {
+        babelrc: false,
+      }).code,
+      "foo();",
+    );
+  });
+
+  it("options throw on falsy true", function() {
+    return assert.throws(function() {
+      babel.transform("", {
+        plugins: [__dirname + "/../../babel-plugin-syntax-jsx", false],
+      });
+    }, /Error: \[BABEL\] unknown: Unexpected falsy value: false/);
+  });
+
+  it("options merge backwards", function() {
     return transformAsync("", {
       presets: [__dirname + "/../../babel-preset-es2015"],
       plugins: [__dirname + "/../../babel-plugin-syntax-jsx"],
-    }).then(function (result) {
-      assert.ok(result.options.plugins[0][0].manipulateOptions.toString().indexOf("jsx") >= 0);
+    }).then(function(result) {
+      assert.ok(
+        result.options.plugins[0][0].manipulateOptions
+          .toString()
+          .indexOf("jsx") >= 0,
+      );
     });
   });
 
-  it("option wrapPluginVisitorMethod", function () {
+  it("option wrapPluginVisitorMethod", function() {
     let calledRaw = 0;
     let calledIntercept = 0;
 
     babel.transform("function foo() { bar(foobar); }", {
-      wrapPluginVisitorMethod: function (pluginAlias, visitorType, callback) {
+      wrapPluginVisitorMethod: function(pluginAlias, visitorType, callback) {
         if (pluginAlias !== "foobar") {
           return callback;
         }
 
         assert.equal(visitorType, "enter");
 
-        return function () {
+        return function() {
           calledIntercept++;
           return callback.apply(this, arguments);
         };
       },
 
-      plugins: [new Plugin({
-        name: "foobar",
-        visitor: {
-          "Program|Identifier": function () {
-            calledRaw++;
+      plugins: [
+        new Plugin({
+          name: "foobar",
+          visitor: {
+            "Program|Identifier": function() {
+              calledRaw++;
+            },
           },
-        },
-      })],
+        }),
+      ],
     });
 
     assert.equal(calledRaw, 4);
     assert.equal(calledIntercept, 4);
   });
 
-  it("pass per preset", function () {
+  it("pass per preset", function() {
     let aliasBaseType = null;
 
     function execTest(passPerPreset) {
@@ -201,13 +236,15 @@ describe("api", function () {
         passPerPreset: passPerPreset,
         presets: [
           // First preset with our plugin, "before"
-          function () {
+          function() {
             return {
               plugins: [
                 new Plugin({
                   visitor: {
-                    Function: function (path) {
-                      const alias = path.scope.getProgramParent().path.get("body")[0].node;
+                    Function: function(path) {
+                      const alias = path.scope
+                        .getProgramParent()
+                        .path.get("body")[0].node;
                       if (!babel.types.isTypeAlias(alias)) return;
 
                       // In case of `passPerPreset` being `false`, the
@@ -230,11 +267,12 @@ describe("api", function () {
           require(__dirname + "/../../babel-preset-es2015"),
 
           // Third preset for Flow.
-          function () {
+          function() {
             return {
               plugins: [
                 require(__dirname + "/../../babel-plugin-syntax-flow"),
-                require(__dirname + "/../../babel-plugin-transform-flow-strip-types"),
+                require(__dirname +
+                  "/../../babel-plugin-transform-flow-strip-types"),
               ],
             };
           },
@@ -248,13 +286,16 @@ describe("api", function () {
 
     assert.equal(aliasBaseType, "NumberTypeAnnotation");
 
-    assert.deepEqual([
-      "\"use strict\";",
-      "",
-      "var x = function x(y) {",
-      "  return y;",
-      "};",
-    ].join("\n"), result.code);
+    assert.deepEqual(
+      [
+        '"use strict";',
+        "",
+        "var x = function x(y) {",
+        "  return y;",
+        "};",
+      ].join("\n"),
+      result.code,
+    );
 
     // 2. passPerPreset: false
 
@@ -264,14 +305,16 @@ describe("api", function () {
 
     assert.equal(aliasBaseType, null);
 
-    assert.deepEqual([
-      "\"use strict\";",
-      "",
-      "var x = function x(y) {",
-      "  return y;",
-      "};",
-    ].join("\n"), result.code);
-
+    assert.deepEqual(
+      [
+        '"use strict";',
+        "",
+        "var x = function x(y) {",
+        "  return y;",
+        "};",
+      ].join("\n"),
+      result.code,
+    );
   });
 
   it("complex plugin and preset ordering", function() {
@@ -279,7 +322,10 @@ describe("api", function () {
       return {
         visitor: {
           Program(path) {
-            path.pushContainer("body", babel.types.expressionStatement(babel.types.identifier(str)));
+            path.pushContainer(
+              "body",
+              babel.types.expressionStatement(babel.types.identifier(str)),
+            );
           },
         },
       };
@@ -290,288 +336,345 @@ describe("api", function () {
     }
 
     const result = babel.transform("", {
-      filename: path.join(__dirname, "fixtures", "config", "complex-plugin-config", "file.js"),
-      presets: [
-        pushPreset("argone"),
-        pushPreset("argtwo"),
-      ],
+      filename: path.join(
+        __dirname,
+        "fixtures",
+        "config",
+        "complex-plugin-config",
+        "file.js",
+      ),
+      presets: [pushPreset("argone"), pushPreset("argtwo")],
       env: {
         development: {
           passPerPreset: true,
-          presets: [
-            pushPreset("argthree"),
-            pushPreset("argfour"),
-          ],
+          presets: [pushPreset("argthree"), pushPreset("argfour")],
           env: {
             development: {
               passPerPreset: true,
-              presets: [
-                pushPreset("argfive"),
-                pushPreset("argsix"),
-              ],
+              presets: [pushPreset("argfive"), pushPreset("argsix")],
             },
           },
         },
       },
     });
 
-    assert.equal(result.code, [
-      "argtwo;",
-      "argone;",
-      "eleven;",
-      "twelve;",
-      "one;",
-      "two;",
-      "five;",
-      "six;",
-      "three;",
-      "four;",
-      "seventeen;",
-      "eighteen;",
-      "nineteen;",
-      "twenty;",
-      "thirteen;",
-      "fourteen;",
-      "fifteen;",
-      "sixteen;",
-      "argfive;",
-      "argsix;",
-      "argthree;",
-      "argfour;",
-      "seven;",
-      "eight;",
-      "nine;",
-      "ten;",
-    ].join("\n"));
+    assert.equal(
+      result.code,
+      [
+        "argtwo;",
+        "argone;",
+        "eleven;",
+        "twelve;",
+        "one;",
+        "two;",
+        "five;",
+        "six;",
+        "three;",
+        "four;",
+        "seventeen;",
+        "eighteen;",
+        "nineteen;",
+        "twenty;",
+        "thirteen;",
+        "fourteen;",
+        "fifteen;",
+        "sixteen;",
+        "argfive;",
+        "argsix;",
+        "argthree;",
+        "argfour;",
+        "seven;",
+        "eight;",
+        "nine;",
+        "ten;",
+      ].join("\n"),
+    );
   });
 
-  it("source map merging", function () {
-    const result = babel.transform([
-      /* eslint-disable max-len */
-      "function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError(\"Cannot call a class as a function\"); } }",
-      "",
-      "let Foo = function Foo() {",
-      "  _classCallCheck(this, Foo);",
-      "};",
-      "",
-      "//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbInN0ZG91dCJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiOztJQUFNLEdBQUcsWUFBSCxHQUFHO3dCQUFILEdBQUciLCJmaWxlIjoidW5kZWZpbmVkIiwic291cmNlc0NvbnRlbnQiOlsiY2xhc3MgRm9vIHt9XG4iXX0=",
-      /* eslint-enable max-len */
-    ].join("\n"), {
-      sourceMap: true,
-    });
+  it("source map merging", function() {
+    const result = babel.transform(
+      [
+        /* eslint-disable max-len */
+        'function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }',
+        "",
+        "let Foo = function Foo() {",
+        "  _classCallCheck(this, Foo);",
+        "};",
+        "",
+        "//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbInN0ZG91dCJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiOztJQUFNLEdBQUcsWUFBSCxHQUFHO3dCQUFILEdBQUciLCJmaWxlIjoidW5kZWZpbmVkIiwic291cmNlc0NvbnRlbnQiOlsiY2xhc3MgRm9vIHt9XG4iXX0=",
+        /* eslint-enable max-len */
+      ].join("\n"),
+      {
+        sourceMap: true,
+      },
+    );
 
-    assert.deepEqual([
-      "function _classCallCheck(instance, Constructor) {",
-      "  if (!(instance instanceof Constructor)) {",
-      "    throw new TypeError(\"Cannot call a class as a function\");",
-      "  }",
-      "}",
-      "",
-      "let Foo = function Foo() {",
-      "  _classCallCheck(this, Foo);",
-      "};",
-    ].join("\n"), result.code);
+    assert.deepEqual(
+      [
+        "function _classCallCheck(instance, Constructor) {",
+        "  if (!(instance instanceof Constructor)) {",
+        '    throw new TypeError("Cannot call a class as a function");',
+        "  }",
+        "}",
+        "",
+        "let Foo = function Foo() {",
+        "  _classCallCheck(this, Foo);",
+        "};",
+      ].join("\n"),
+      result.code,
+    );
 
     const consumer = new sourceMap.SourceMapConsumer(result.map);
 
-    assert.deepEqual(consumer.originalPositionFor({
-      line: 7,
-      column: 4,
-    }), {
-      name: null,
-      source: "stdout",
-      line: 1,
-      column: 6,
-    });
+    assert.deepEqual(
+      consumer.originalPositionFor({
+        line: 7,
+        column: 4,
+      }),
+      {
+        name: null,
+        source: "stdout",
+        line: 1,
+        column: 6,
+      },
+    );
   });
 
-  it("code option false", function () {
-    return transformAsync("foo('bar');", { code: false }).then(function (result) {
+  it("code option false", function() {
+    return transformAsync("foo('bar');", { code: false }).then(function(
+      result,
+    ) {
       assert.ok(!result.code);
     });
   });
 
-  it("ast option false", function () {
-    return transformAsync("foo('bar');", { ast: false }).then(function (result) {
+  it("ast option false", function() {
+    return transformAsync("foo('bar');", { ast: false }).then(function(result) {
       assert.ok(!result.ast);
     });
   });
 
-  it("auxiliaryComment option", function () {
+  it("auxiliaryComment option", function() {
     return transformAsync("class Foo {}", {
       auxiliaryCommentBefore: "before",
       auxiliaryCommentAfter: "after",
-      plugins: [function (babel) {
-        const t = babel.types;
-        return {
-          visitor: {
-            Program: function (path) {
-              path.unshiftContainer("body", t.expressionStatement(t.identifier("start")));
-              path.pushContainer("body", t.expressionStatement(t.identifier("end")));
+      plugins: [
+        function(babel) {
+          const t = babel.types;
+          return {
+            visitor: {
+              Program: function(path) {
+                path.unshiftContainer(
+                  "body",
+                  t.expressionStatement(t.identifier("start")),
+                );
+                path.pushContainer(
+                  "body",
+                  t.expressionStatement(t.identifier("end")),
+                );
+              },
             },
-          },
-        };
-      }],
-    }).then(function (result) {
-      assert.equal(result.code,
-        "/*before*/start;\n/*after*/class Foo {}\n/*before*/end;\n/*after*/");
+          };
+        },
+      ],
+    }).then(function(result) {
+      assert.equal(
+        result.code,
+        "/*before*/start;\n/*after*/class Foo {}\n/*before*/end;\n/*after*/",
+      );
     });
   });
 
-  it("modules metadata", function () {
+  it("modules metadata", function() {
     return Promise.all([
       // eslint-disable-next-line max-len
-      transformAsync("import { externalName as localName } from \"external\";").then(function (result) {
+      transformAsync(
+        'import { externalName as localName } from "external";',
+      ).then(function(result) {
         assert.deepEqual(result.metadata.modules.imports[0], {
           source: "external",
           imported: ["externalName"],
-          specifiers: [{
-            kind: "named",
-            imported: "externalName",
-            local: "localName",
-          }],
+          specifiers: [
+            {
+              kind: "named",
+              imported: "externalName",
+              local: "localName",
+            },
+          ],
         });
       }),
 
-      transformAsync("import * as localName2 from \"external\";").then(function (result) {
+      transformAsync('import * as localName2 from "external";').then(function(
+        result,
+      ) {
         assert.deepEqual(result.metadata.modules.imports[0], {
           source: "external",
           imported: ["*"],
-          specifiers: [{
-            kind: "namespace",
-            local: "localName2",
-          }],
+          specifiers: [
+            {
+              kind: "namespace",
+              local: "localName2",
+            },
+          ],
         });
       }),
 
-      transformAsync("import localName3 from \"external\";").then(function (result) {
+      transformAsync('import localName3 from "external";').then(function(
+        result,
+      ) {
         assert.deepEqual(result.metadata.modules.imports[0], {
           source: "external",
           imported: ["default"],
-          specifiers: [{
-            kind: "named",
-            imported: "default",
-            local: "localName3",
-          }],
+          specifiers: [
+            {
+              kind: "named",
+              imported: "default",
+              local: "localName3",
+            },
+          ],
         });
       }),
 
-      transformAsync("import localName from \"./array\";", {
+      transformAsync('import localName from "./array";', {
         resolveModuleSource: function() {
           return "override-source";
         },
-      }).then(function (result) {
+      }).then(function(result) {
         assert.deepEqual(result.metadata.modules.imports, [
           {
             source: "override-source",
             imported: ["default"],
             specifiers: [
               {
-                "kind": "named",
-                "imported": "default",
-                "local": "localName",
+                kind: "named",
+                imported: "default",
+                local: "localName",
               },
             ],
           },
         ]);
       }),
 
-      transformAsync("export * as externalName1 from \"external\";", {
+      transformAsync('export * as externalName1 from "external";', {
         plugins: [require("../../babel-plugin-syntax-export-extensions")],
-      }).then(function (result) {
+      }).then(function(result) {
         assert.deepEqual(result.metadata.modules.exports, {
           exported: ["externalName1"],
-          specifiers: [{
-            kind: "external-namespace",
-            exported: "externalName1",
-            source: "external",
-          }],
+          specifiers: [
+            {
+              kind: "external-namespace",
+              exported: "externalName1",
+              source: "external",
+            },
+          ],
         });
       }),
 
-      transformAsync("export externalName2 from \"external\";", {
+      transformAsync('export externalName2 from "external";', {
         plugins: [require("../../babel-plugin-syntax-export-extensions")],
-      }).then(function (result) {
+      }).then(function(result) {
         assert.deepEqual(result.metadata.modules.exports, {
           exported: ["externalName2"],
-          specifiers: [{
-            kind: "external",
-            local: "externalName2",
-            exported: "externalName2",
-            source: "external",
-          }],
+          specifiers: [
+            {
+              kind: "external",
+              local: "externalName2",
+              exported: "externalName2",
+              source: "external",
+            },
+          ],
         });
       }),
 
-      transformAsync("export function namedFunction() {}").then(function (result) {
+      transformAsync("export function namedFunction() {}").then(function(
+        result,
+      ) {
         assert.deepEqual(result.metadata.modules.exports, {
           exported: ["namedFunction"],
-          specifiers: [{
-            kind: "local",
-            local: "namedFunction",
-            exported: "namedFunction",
-          }],
+          specifiers: [
+            {
+              kind: "local",
+              local: "namedFunction",
+              exported: "namedFunction",
+            },
+          ],
         });
       }),
 
-      transformAsync("export var foo = \"bar\";").then(function (result) {
+      transformAsync('export var foo = "bar";').then(function(result) {
         assert.deepEqual(result.metadata.modules.exports, {
-          "exported": ["foo"],
-          specifiers: [{
-            kind: "local",
-            local: "foo",
-            exported: "foo",
-          }],
+          exported: ["foo"],
+          specifiers: [
+            {
+              kind: "local",
+              local: "foo",
+              exported: "foo",
+            },
+          ],
         });
       }),
 
-      transformAsync("export { localName as externalName3 };").then(function (result) {
+      transformAsync("export { localName as externalName3 };").then(function(
+        result,
+      ) {
         assert.deepEqual(result.metadata.modules.exports, {
           exported: ["externalName3"],
-          specifiers: [{
-            kind: "local",
-            local: "localName",
-            exported: "externalName3",
-          }],
+          specifiers: [
+            {
+              kind: "local",
+              local: "localName",
+              exported: "externalName3",
+            },
+          ],
         });
       }),
 
-      transformAsync("export { externalName4 } from \"external\";").then(function (result) {
+      transformAsync('export { externalName4 } from "external";').then(function(
+        result,
+      ) {
         assert.deepEqual(result.metadata.modules.exports, {
           exported: ["externalName4"],
-          specifiers: [{
-            kind: "external",
-            local: "externalName4",
-            exported: "externalName4",
-            source: "external",
-          }],
+          specifiers: [
+            {
+              kind: "external",
+              local: "externalName4",
+              exported: "externalName4",
+              source: "external",
+            },
+          ],
         });
       }),
 
-      transformAsync("export * from \"external\";").then(function (result) {
+      transformAsync('export * from "external";').then(function(result) {
         assert.deepEqual(result.metadata.modules.exports, {
           exported: [],
-          specifiers: [{
-            kind: "external-all",
-            source: "external",
-          }],
+          specifiers: [
+            {
+              kind: "external-all",
+              source: "external",
+            },
+          ],
         });
       }),
 
-      transformAsync("export default function defaultFunction() {}").then(function (result) {
+      transformAsync(
+        "export default function defaultFunction() {}",
+      ).then(function(result) {
         assert.deepEqual(result.metadata.modules.exports, {
           exported: ["defaultFunction"],
-          specifiers: [{
-            kind: "local",
-            local: "defaultFunction",
-            exported: "default",
-          }],
+          specifiers: [
+            {
+              kind: "local",
+              local: "defaultFunction",
+              exported: "default",
+            },
+          ],
         });
       }),
     ]);
   });
 
-  it("ignore option", function () {
+  it("ignore option", function() {
     return Promise.all([
       transformAsync("", {
         ignore: ["/foo"],
@@ -610,7 +713,7 @@ describe("api", function () {
     ]);
   });
 
-  it("only option", function () {
+  it("only option", function() {
     return Promise.all([
       transformAsync("", {
         only: ["/foo"],
@@ -649,23 +752,23 @@ describe("api", function () {
     ]);
   });
 
-  describe("env option", function () {
+  describe("env option", function() {
     const oldBabelEnv = process.env.BABEL_ENV;
     const oldNodeEnv = process.env.NODE_ENV;
 
-    setup(function () {
+    setup(function() {
       // Tests need to run with the default and specific values for these. They
       // need to be cleared for each test.
       delete process.env.BABEL_ENV;
       delete process.env.NODE_ENV;
     });
 
-    suiteTeardown(function () {
+    suiteTeardown(function() {
       process.env.BABEL_ENV = oldBabelEnv;
       process.env.NODE_ENV = oldNodeEnv;
     });
 
-    it("default", function () {
+    it("default", function() {
       const result = babel.transform("foo;", {
         env: {
           development: { code: false },
@@ -675,7 +778,7 @@ describe("api", function () {
       assert.equal(result.code, undefined);
     });
 
-    it("BABEL_ENV", function () {
+    it("BABEL_ENV", function() {
       process.env.BABEL_ENV = "foo";
       const result = babel.transform("foo;", {
         env: {
@@ -685,7 +788,7 @@ describe("api", function () {
       assert.equal(result.code, undefined);
     });
 
-    it("NODE_ENV", function () {
+    it("NODE_ENV", function() {
       process.env.NODE_ENV = "foo";
       const result = babel.transform("foo;", {
         env: {
@@ -696,41 +799,43 @@ describe("api", function () {
     });
   });
 
-  it("resolveModuleSource option", function () {
+  it("resolveModuleSource option", function() {
     /* eslint-disable max-len */
-    const actual = "import foo from \"foo-import-default\";\nimport \"foo-import-bare\";\nexport { foo } from \"foo-export-named\";";
-    const expected = "import foo from \"resolved/foo-import-default\";\nimport \"resolved/foo-import-bare\";\nexport { foo } from \"resolved/foo-export-named\";";
+    const actual =
+      'import foo from "foo-import-default";\nimport "foo-import-bare";\nexport { foo } from "foo-export-named";';
+    const expected =
+      'import foo from "resolved/foo-import-default";\nimport "resolved/foo-import-bare";\nexport { foo } from "resolved/foo-export-named";';
     /* eslint-enable max-len */
 
     return transformAsync(actual, {
-      resolveModuleSource: function (originalSource) {
+      resolveModuleSource: function(originalSource) {
         return "resolved/" + originalSource;
       },
-    }).then(function (result) {
+    }).then(function(result) {
       assert.equal(result.code.trim(), expected);
     });
   });
 
-  describe("buildExternalHelpers", function () {
-    it("all", function () {
+  describe("buildExternalHelpers", function() {
+    it("all", function() {
       const script = buildExternalHelpers();
       assert.ok(script.indexOf("classCallCheck") >= -1);
       assert.ok(script.indexOf("inherits") >= 0);
     });
 
-    it("whitelist", function () {
+    it("whitelist", function() {
       const script = buildExternalHelpers(["inherits"]);
       assert.ok(script.indexOf("classCallCheck") === -1);
       assert.ok(script.indexOf("inherits") >= 0);
     });
 
-    it("empty whitelist", function () {
+    it("empty whitelist", function() {
       const script = buildExternalHelpers([]);
       assert.ok(script.indexOf("classCallCheck") === -1);
       assert.ok(script.indexOf("inherits") === -1);
     });
 
-    it("underscored", function () {
+    it("underscored", function() {
       const script = buildExternalHelpers(["typeof"]);
       assert.ok(script.indexOf("typeof") >= 0);
     });
diff --git a/packages/babel-core/test/browserify.js b/packages/babel-core/test/browserify.js
index e8e8f27c82..6f91c3f3fc 100644
--- a/packages/babel-core/test/browserify.js
+++ b/packages/babel-core/test/browserify.js
@@ -5,7 +5,9 @@ import vm from "vm";
 
 describe("browserify", function() {
   it("babel/register may be used without breaking browserify", function(done) {
-    const bundler = browserify(path.join(__dirname, "fixtures/browserify/register.js"));
+    const bundler = browserify(
+      path.join(__dirname, "fixtures/browserify/register.js"),
+    );
 
     bundler.bundle(function(err, bundle) {
       if (err) return done(err);
diff --git a/packages/babel-core/test/caching-api.js b/packages/babel-core/test/caching-api.js
index 914214540b..d846fd85bb 100644
--- a/packages/babel-core/test/caching-api.js
+++ b/packages/babel-core/test/caching-api.js
@@ -27,7 +27,6 @@ describe("caching API", () => {
       return { arg, count: count++ };
     });
 
-
     assert.deepEqual(fn("one"), { arg: "one", count: 0 });
     assert.equal(fn("one"), fn("one"));
 
@@ -210,48 +209,97 @@ describe("caching API", () => {
       return { arg, val, val2, count: count++ };
     });
 
-    assert.deepEqual(fn("one"), { arg: "one", val: "default", val2: "another", count: 0 });
+    assert.deepEqual(fn("one"), {
+      arg: "one",
+      val: "default",
+      val2: "another",
+      count: 0,
+    });
     assert.equal(fn("one"), fn("one"));
 
-    assert.deepEqual(fn("two"), { arg: "two", val: "default", val2: "another", count: 1 });
+    assert.deepEqual(fn("two"), {
+      arg: "two",
+      val: "default",
+      val2: "another",
+      count: 1,
+    });
     assert.equal(fn("two"), fn("two"));
 
     other = "new";
 
-    assert.deepEqual(fn("one"), { arg: "one", val: "new", val2: "another", count: 2 });
+    assert.deepEqual(fn("one"), {
+      arg: "one",
+      val: "new",
+      val2: "another",
+      count: 2,
+    });
     assert.equal(fn("one"), fn("one"));
 
-    assert.deepEqual(fn("two"), { arg: "two", val: "new", val2: "another", count: 3 });
+    assert.deepEqual(fn("two"), {
+      arg: "two",
+      val: "new",
+      val2: "another",
+      count: 3,
+    });
     assert.equal(fn("two"), fn("two"));
 
     other = "default";
 
-    assert.deepEqual(fn("one"), { arg: "one", val: "default", val2: "another", count: 4 });
+    assert.deepEqual(fn("one"), {
+      arg: "one",
+      val: "default",
+      val2: "another",
+      count: 4,
+    });
     assert.equal(fn("one"), fn("one"));
 
-    assert.deepEqual(fn("two"), { arg: "two", val: "default", val2: "another", count: 5 });
+    assert.deepEqual(fn("two"), {
+      arg: "two",
+      val: "default",
+      val2: "another",
+      count: 5,
+    });
     assert.equal(fn("two"), fn("two"));
 
     other = "new";
 
-    assert.deepEqual(fn("one"), { arg: "one", val: "new", val2: "another", count: 6 });
+    assert.deepEqual(fn("one"), {
+      arg: "one",
+      val: "new",
+      val2: "another",
+      count: 6,
+    });
     assert.equal(fn("one"), fn("one"));
 
-    assert.deepEqual(fn("two"), { arg: "two", val: "new", val2: "another", count: 7 });
+    assert.deepEqual(fn("two"), {
+      arg: "two",
+      val: "new",
+      val2: "another",
+      count: 7,
+    });
     assert.equal(fn("two"), fn("two"));
 
     another = "second";
 
-    assert.deepEqual(fn("one"), { arg: "one", val: "new", val2: "second", count: 8 });
+    assert.deepEqual(fn("one"), {
+      arg: "one",
+      val: "new",
+      val2: "second",
+      count: 8,
+    });
     assert.equal(fn("one"), fn("one"));
 
-    assert.deepEqual(fn("two"), { arg: "two", val: "new", val2: "second", count: 9 });
+    assert.deepEqual(fn("two"), {
+      arg: "two",
+      val: "new",
+      val2: "second",
+      count: 9,
+    });
     assert.equal(fn("two"), fn("two"));
-
   });
 
   it("should throw if caching is never configured and not defaulting", () => {
-    const fn = makeStrongCache(() => { }, false /* autoPermacache */);
+    const fn = makeStrongCache(() => {}, false /* autoPermacache */);
 
     assert.throws(() => fn(), /Error: Caching was left unconfigured./);
   });
@@ -259,7 +307,7 @@ describe("caching API", () => {
   it("should auto-permacache by default", () => {
     let count = 0;
 
-    const fn = makeStrongCache((arg) => ({ arg, count: count++ }));
+    const fn = makeStrongCache(arg => ({ arg, count: count++ }));
 
     assert.deepEqual(fn("one"), { arg: "one", count: 0 });
     assert.equal(fn("one"), fn("one"));
@@ -333,7 +381,10 @@ describe("caching API", () => {
   it("should throw if you configure .forever after exiting", () => {
     const fn = makeStrongCache((arg, cache) => cache);
 
-    assert.throws(() => fn().forever(), /Cannot change caching after evaluation/);
+    assert.throws(
+      () => fn().forever(),
+      /Cannot change caching after evaluation/,
+    );
   });
 
   it("should throw if you configure .never after exiting", () => {
@@ -345,12 +396,18 @@ describe("caching API", () => {
   it("should throw if you configure .using after exiting", () => {
     const fn = makeStrongCache((arg, cache) => cache);
 
-    assert.throws(() => fn().using(() => null), /Cannot change caching after evaluation/);
+    assert.throws(
+      () => fn().using(() => null),
+      /Cannot change caching after evaluation/,
+    );
   });
 
   it("should throw if you configure .invalidate after exiting", () => {
     const fn = makeStrongCache((arg, cache) => cache);
 
-    assert.throws(() => fn().invalidate(() => null), /Cannot change caching after evaluation/);
+    assert.throws(
+      () => fn().invalidate(() => null),
+      /Cannot change caching after evaluation/,
+    );
   });
 });
diff --git a/packages/babel-core/test/config-chain.js b/packages/babel-core/test/config-chain.js
index 269e6053f7..3f93a7d18c 100644
--- a/packages/babel-core/test/config-chain.js
+++ b/packages/babel-core/test/config-chain.js
@@ -4,7 +4,7 @@ import buildConfigChain from "../lib/config/build-config-chain";
 
 function fixture() {
   const args = [__dirname, "fixtures", "config"];
-  for (let i = 0; i < arguments.length; i ++) {
+  for (let i = 0; i < arguments.length; i++) {
     args.push(arguments[i]);
   }
   return path.join.apply(path, args);
@@ -14,11 +14,11 @@ function base() {
   return process.cwd();
 }
 
-describe("buildConfigChain", function () {
+describe("buildConfigChain", function() {
   let oldBabelEnv;
   let oldNodeEnv;
 
-  beforeEach(function () {
+  beforeEach(function() {
     oldBabelEnv = process.env.BABEL_ENV;
     oldNodeEnv = process.env.NODE_ENV;
 
@@ -26,7 +26,7 @@ describe("buildConfigChain", function () {
     delete process.env.NODE_ENV;
   });
 
-  afterEach(function () {
+  afterEach(function() {
     process.env.BABEL_ENV = oldBabelEnv;
     process.env.NODE_ENV = oldNodeEnv;
   });
@@ -52,7 +52,7 @@ describe("buildConfigChain", function () {
     });
   });
 
-  it("dir1", function () {
+  it("dir1", function() {
     const chain = buildConfigChain({
       filename: fixture("dir1", "src.js"),
     });
@@ -61,9 +61,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "extended",
-          ],
+          plugins: ["extended"],
         },
         alias: fixture("extended.babelrc.json"),
         loc: fixture("extended.babelrc.json"),
@@ -72,9 +70,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "root",
-          ],
+          plugins: ["root"],
         },
         alias: fixture(".babelrc"),
         loc: fixture(".babelrc"),
@@ -83,9 +79,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -105,7 +99,7 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-  it("dir2", function () {
+  it("dir2", function() {
     const chain = buildConfigChain({
       filename: fixture("dir2", "src.js"),
     });
@@ -114,9 +108,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -125,9 +117,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "dir2",
-          ],
+          plugins: ["dir2"],
         },
         alias: fixture("dir2", ".babelrc"),
         loc: fixture("dir2", ".babelrc"),
@@ -147,7 +137,7 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-  it("dir3", function () {
+  it("dir3", function() {
     const chain = buildConfigChain({
       filename: fixture("dir3", "src.js"),
     });
@@ -156,9 +146,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "extended",
-          ],
+          plugins: ["extended"],
         },
         alias: fixture("extended.babelrc.json"),
         loc: fixture("extended.babelrc.json"),
@@ -167,9 +155,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "root",
-          ],
+          plugins: ["root"],
         },
         alias: fixture(".babelrc"),
         loc: fixture(".babelrc"),
@@ -178,9 +164,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -200,7 +184,7 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-  it("env - base", function () {
+  it("env - base", function() {
     const chain = buildConfigChain({
       filename: fixture("env", "src.js"),
     });
@@ -209,9 +193,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -220,9 +202,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "env-base",
-          ],
+          plugins: ["env-base"],
         },
         alias: fixture("env", ".babelrc"),
         loc: fixture("env", ".babelrc"),
@@ -242,7 +222,7 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-  it("env - foo", function () {
+  it("env - foo", function() {
     process.env.NODE_ENV = "foo";
 
     const chain = buildConfigChain({
@@ -253,9 +233,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -264,9 +242,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "env-base",
-          ],
+          plugins: ["env-base"],
         },
         alias: fixture("env", ".babelrc"),
         loc: fixture("env", ".babelrc"),
@@ -275,9 +251,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "env-foo",
-          ],
+          plugins: ["env-foo"],
         },
         alias: fixture("env", ".babelrc.env.foo"),
         loc: fixture("env", ".babelrc.env.foo"),
@@ -297,7 +271,7 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-  it("env - bar", function () {
+  it("env - bar", function() {
     process.env.NODE_ENV = "foo"; // overridden
     process.env.NODE_ENV = "bar";
 
@@ -309,9 +283,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -320,9 +292,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "env-base",
-          ],
+          plugins: ["env-base"],
         },
         alias: fixture("env", ".babelrc"),
         loc: fixture("env", ".babelrc"),
@@ -331,9 +301,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "env-bar",
-          ],
+          plugins: ["env-bar"],
         },
         alias: fixture("env", ".babelrc.env.bar"),
         loc: fixture("env", ".babelrc.env.bar"),
@@ -353,8 +321,7 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-
-  it("env - foo", function () {
+  it("env - foo", function() {
     process.env.NODE_ENV = "foo";
 
     const chain = buildConfigChain({
@@ -394,7 +361,7 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-  it("js-config", function () {
+  it("js-config", function() {
     const chain = buildConfigChain({
       filename: fixture("js-config", "src.js"),
     });
@@ -403,9 +370,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -414,10 +379,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "foo",
-            "bar",
-          ],
+          plugins: ["foo", "bar"],
         },
         alias: fixture("js-config", ".babelrc.js"),
         loc: fixture("js-config", ".babelrc.js"),
@@ -437,7 +399,7 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-  it("js-config-function", function () {
+  it("js-config-function", function() {
     const chain = buildConfigChain({
       filename: fixture("js-config-function", "src.js"),
     });
@@ -446,9 +408,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -477,7 +437,7 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-  it("js-config-default - should read transpiled export default", function () {
+  it("js-config-default - should read transpiled export default", function() {
     const chain = buildConfigChain({
       filename: fixture("js-config-default", "src.js"),
     });
@@ -486,9 +446,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -497,10 +455,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "foo",
-            "bar",
-          ],
+          plugins: ["foo", "bar"],
         },
         alias: fixture("js-config-default", ".babelrc.js"),
         loc: fixture("js-config-default", ".babelrc.js"),
@@ -519,7 +474,7 @@ describe("buildConfigChain", function () {
 
     assert.deepEqual(chain, expected);
   });
-  it("js-config-extended", function () {
+  it("js-config-extended", function() {
     const chain = buildConfigChain({
       filename: fixture("js-config-extended", "src.js"),
     });
@@ -528,9 +483,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -539,9 +492,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "extended",
-          ],
+          plugins: ["extended"],
         },
         alias: fixture("extended.babelrc.json"),
         loc: fixture("extended.babelrc.json"),
@@ -550,10 +501,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          plugins: [
-            "foo",
-            "bar",
-          ],
+          plugins: ["foo", "bar"],
         },
         alias: fixture("js-config-extended", ".babelrc.js"),
         loc: fixture("js-config-extended", ".babelrc.js"),
@@ -573,50 +521,49 @@ describe("buildConfigChain", function () {
     assert.deepEqual(chain, expected);
   });
 
-  it("json-pkg-config-no-babel - should not throw if" +
-    " package.json doesn't contain a `babel` field", function () {
-    const chain = buildConfigChain({
-      filename: fixture("json-pkg-config-no-babel", "src.js"),
-    });
+  it(
+    "json-pkg-config-no-babel - should not throw if" +
+      " package.json doesn't contain a `babel` field",
+    function() {
+      const chain = buildConfigChain({
+        filename: fixture("json-pkg-config-no-babel", "src.js"),
+      });
 
-    const expected = [
-      {
-        type: "options",
-        options: {
-          ignore: [
-            "root-ignore",
-          ],
+      const expected = [
+        {
+          type: "options",
+          options: {
+            ignore: ["root-ignore"],
+          },
+          alias: fixture(".babelignore"),
+          loc: fixture(".babelignore"),
+          dirname: fixture(),
         },
-        alias: fixture(".babelignore"),
-        loc: fixture(".babelignore"),
-        dirname: fixture(),
-      },
-      {
-        type: "options",
-        options: {
-          plugins: [
-            "json",
-          ],
+        {
+          type: "options",
+          options: {
+            plugins: ["json"],
+          },
+          alias: fixture("json-pkg-config-no-babel", ".babelrc"),
+          loc: fixture("json-pkg-config-no-babel", ".babelrc"),
+          dirname: fixture("json-pkg-config-no-babel"),
         },
-        alias: fixture("json-pkg-config-no-babel", ".babelrc"),
-        loc: fixture("json-pkg-config-no-babel", ".babelrc"),
-        dirname: fixture("json-pkg-config-no-babel"),
-      },
-      {
-        type: "arguments",
-        options: {
-          filename: fixture("json-pkg-config-no-babel", "src.js"),
+        {
+          type: "arguments",
+          options: {
+            filename: fixture("json-pkg-config-no-babel", "src.js"),
+          },
+          alias: "base",
+          loc: "base",
+          dirname: base(),
         },
-        alias: "base",
-        loc: "base",
-        dirname: base(),
-      },
-    ];
+      ];
 
-    assert.deepEqual(chain, expected);
-  });
+      assert.deepEqual(chain, expected);
+    },
+  );
 
-  it("should not ignore file matching negated file pattern", function () {
+  it("should not ignore file matching negated file pattern", function() {
     const chain = buildConfigChain({
       filename: fixture("ignore-negate", "src.js"),
     });
@@ -625,9 +572,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -636,10 +581,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "*",
-            "!src.js",
-          ],
+          ignore: ["*", "!src.js"],
         },
         alias: fixture("ignore-negate", ".babelrc"),
         loc: fixture("ignore-negate", ".babelrc"),
@@ -665,7 +607,7 @@ describe("buildConfigChain", function () {
     assert.equal(chain2, null);
   });
 
-  it("should not ignore file matching negated folder pattern", function () {
+  it("should not ignore file matching negated folder pattern", function() {
     const chain = buildConfigChain({
       filename: fixture("ignore-negate-folder", "folder", "src.js"),
     });
@@ -674,9 +616,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "root-ignore",
-          ],
+          ignore: ["root-ignore"],
         },
         alias: fixture(".babelignore"),
         loc: fixture(".babelignore"),
@@ -685,10 +625,7 @@ describe("buildConfigChain", function () {
       {
         type: "options",
         options: {
-          ignore: [
-            "*",
-            "!folder",
-          ],
+          ignore: ["*", "!folder"],
         },
         alias: fixture("ignore-negate-folder", ".babelrc"),
         loc: fixture("ignore-negate-folder", ".babelrc"),
@@ -714,83 +651,71 @@ describe("buildConfigChain", function () {
     assert.equal(chain2, null);
   });
 
-  it("js-json-config - should throw an error if both a .babelrc" +
-    " and a .babelrc.js are present", function () {
-    assert.throws(
-      function () {
+  it(
+    "js-json-config - should throw an error if both a .babelrc" +
+      " and a .babelrc.js are present",
+    function() {
+      assert.throws(function() {
         buildConfigChain({
           filename: fixture("js-json-config", "src.js"),
         });
-      },
-      /Multiple configuration files found\.(.|\n)*\.babelrc(.|\n)*\.babelrc\.js/
-    );
-  });
+      }, /Multiple configuration files found\.(.|\n)*\.babelrc(.|\n)*\.babelrc\.js/);
+    },
+  );
 
-  it("js-pkg-config - should throw an error if both a .babelrc.js" +
-    " and a package.json with a babel field are present", function () {
-    assert.throws(
-      function () {
+  it(
+    "js-pkg-config - should throw an error if both a .babelrc.js" +
+      " and a package.json with a babel field are present",
+    function() {
+      assert.throws(function() {
         buildConfigChain({
           filename: fixture("js-pkg-config", "src.js"),
         });
-      },
-      /Multiple configuration files found\.(.|\n)*\.babelrc\.js(.|\n)*package\.json/
-    );
-  });
+      }, /Multiple configuration files found\.(.|\n)*\.babelrc\.js(.|\n)*package\.json/);
+    },
+  );
 
-  it("json-pkg-config - should throw an error if both a .babelrc" +
-    " and a package.json with a babel field are present", function () {
-    assert.throws(
-      function () {
+  it(
+    "json-pkg-config - should throw an error if both a .babelrc" +
+      " and a package.json with a babel field are present",
+    function() {
+      assert.throws(function() {
         buildConfigChain({
           filename: fixture("json-pkg-config", "src.js"),
         });
-      },
-      /Multiple configuration files found\.(.|\n)*\.babelrc(.|\n)*package\.json/
-    );
+      }, /Multiple configuration files found\.(.|\n)*\.babelrc(.|\n)*package\.json/);
+    },
+  );
+
+  it("js-config-error", function() {
+    assert.throws(function() {
+      buildConfigChain({
+        filename: fixture("js-config-error", "src.js"),
+      });
+    }, /Error while loading config/);
   });
 
-  it("js-config-error", function () {
-    assert.throws(
-      function () {
-        buildConfigChain({
-          filename: fixture("js-config-error", "src.js"),
-        });
-      },
-      /Error while loading config/
-    );
+  it("js-config-error2", function() {
+    assert.throws(function() {
+      buildConfigChain({
+        filename: fixture("js-config-error2", "src.js"),
+      });
+    }, /Configuration should be an exported JavaScript object/);
   });
 
-  it("js-config-error2", function () {
-    assert.throws(
-      function () {
-        buildConfigChain({
-          filename: fixture("js-config-error2", "src.js"),
-        });
-      },
-      /Configuration should be an exported JavaScript object/
-    );
+  it("js-config-error3", function() {
+    assert.throws(function() {
+      buildConfigChain({
+        filename: fixture("js-config-error3", "src.js"),
+      });
+    }, /Configuration should be an exported JavaScript object/);
   });
 
-  it("js-config-error3", function () {
-    assert.throws(
-      function () {
-        buildConfigChain({
-          filename: fixture("js-config-error3", "src.js"),
-        });
-      },
-      /Configuration should be an exported JavaScript object/
-    );
-  });
-
-  it("json-config-error", function () {
-    assert.throws(
-      function () {
-        buildConfigChain({
-          filename: fixture("json-config-error", "src.js"),
-        });
-      },
-      /Error while parsing config/
-    );
+  it("json-config-error", function() {
+    assert.throws(function() {
+      buildConfigChain({
+        filename: fixture("json-config-error", "src.js"),
+      });
+    }, /Error while parsing config/);
   });
 });
diff --git a/packages/babel-core/test/evaluation.js b/packages/babel-core/test/evaluation.js
index ca86f51839..f055238322 100644
--- a/packages/babel-core/test/evaluation.js
+++ b/packages/babel-core/test/evaluation.js
@@ -2,20 +2,23 @@ import traverse from "babel-traverse";
 import assert from "assert";
 import { parse } from "babylon";
 
-describe("evaluation", function () {
+describe("evaluation", function() {
   function addTest(code, type, value, notConfident) {
-    it(type + ": " + code, function () {
+    it(type + ": " + code, function() {
       const visitor = {};
 
-      visitor[type] = function (path) {
+      visitor[type] = function(path) {
         const evaluate = path.evaluate();
         assert.equal(evaluate.confident, !notConfident);
         assert.deepEqual(evaluate.value, value);
       };
 
-      traverse(parse(code, {
-        plugins: ["*"],
-      }), visitor);
+      traverse(
+        parse(code, {
+          plugins: ["*"],
+        }),
+        visitor,
+      );
     });
   }
 
@@ -56,14 +59,39 @@ describe("evaluation", function () {
   addTest("'abc' === 'xyz' || 1 === 1", "LogicalExpression", true);
   addTest("'abc' === 'xyz' || 1 === 10", "LogicalExpression", false);
   addTest("'abc' === 'abc' || config.flag === 1", "LogicalExpression", true);
-  addTest("obj.a === 'abc' || config.flag === 1", "LogicalExpression", undefined, true);
+  addTest(
+    "obj.a === 'abc' || config.flag === 1",
+    "LogicalExpression",
+    undefined,
+    true,
+  );
   addTest("'abc' !== 'abc' && config.flag === 1", "LogicalExpression", false);
   addTest("obj.a === 'abc' && 1 === 1", "LogicalExpression", undefined, true);
-  addTest("'abc' === 'abc' && (1 === 1 || config.flag)", "LogicalExpression", true);
-  addTest("'abc' === 'xyz' || (1 === 1 && config.flag)", "LogicalExpression", undefined, true);
-  addTest("'abc' === 'xyz' || (1 === 1 && 'four' === 'four')", "LogicalExpression", true);
-  addTest("'abc' === 'abc' && (1 === 1 && 'four' === 'four')", "LogicalExpression", true);
+  addTest(
+    "'abc' === 'abc' && (1 === 1 || config.flag)",
+    "LogicalExpression",
+    true,
+  );
+  addTest(
+    "'abc' === 'xyz' || (1 === 1 && config.flag)",
+    "LogicalExpression",
+    undefined,
+    true,
+  );
+  addTest(
+    "'abc' === 'xyz' || (1 === 1 && 'four' === 'four')",
+    "LogicalExpression",
+    true,
+  );
+  addTest(
+    "'abc' === 'abc' && (1 === 1 && 'four' === 'four')",
+    "LogicalExpression",
+    true,
+  );
   addTest("({})", "ObjectExpression", {});
   addTest("({a: '1'})", "ObjectExpression", { a: "1" });
-  addTest("({['a' + 'b']: 10 * 20, 'z': [1, 2, 3]})", "ObjectExpression", { ab: 200, z: [1, 2, 3] });
+  addTest("({['a' + 'b']: 10 * 20, 'z': [1, 2, 3]})", "ObjectExpression", {
+    ab: 200,
+    z: [1, 2, 3],
+  });
 });
diff --git a/packages/babel-core/test/option-manager.js b/packages/babel-core/test/option-manager.js
index cf2fcaa484..3868d456fa 100644
--- a/packages/babel-core/test/option-manager.js
+++ b/packages/babel-core/test/option-manager.js
@@ -6,55 +6,51 @@ describe("option-manager", () => {
   it("throws for babel 5 plugin", () => {
     return assert.throws(() => {
       manageOptions({
-        plugins: [
-          ({ Plugin }) => new Plugin("object-assign", {}),
-        ],
+        plugins: [({ Plugin }) => new Plugin("object-assign", {})],
       });
     }, /Babel 5 plugin is being run with Babel 6/);
   });
 
   describe("mergeOptions", () => {
     it("throws for removed babel 5 options", () => {
-      return assert.throws(
-        () => {
-          manageOptions({
-            "randomOption": true,
-          });
-        },
-        /Unknown option: base.randomOption/
-      );
+      return assert.throws(() => {
+        manageOptions({
+          randomOption: true,
+        });
+      }, /Unknown option: base.randomOption/);
     });
 
     it("throws for removed babel 5 options", () => {
       return assert.throws(
         () => {
           manageOptions({
-            "auxiliaryComment": true,
-            "blacklist": true,
+            auxiliaryComment: true,
+            blacklist: true,
           });
         },
         // eslint-disable-next-line max-len
-        /Using removed Babel 5 option: base.auxiliaryComment - Use `auxiliaryCommentBefore` or `auxiliaryCommentAfter`/
+        /Using removed Babel 5 option: base.auxiliaryComment - Use `auxiliaryCommentBefore` or `auxiliaryCommentAfter`/,
       );
     });
 
     it("throws for resolved but erroring preset", () => {
-      return assert.throws(
-        () => {
-          manageOptions({
-            "presets": [path.join(__dirname, "fixtures/option-manager/not-a-preset")],
-          });
-        },
-        /While processing: .*option-manager(?:\/|\\\\)not-a-preset\.js/
-      );
+      return assert.throws(() => {
+        manageOptions({
+          presets: [
+            path.join(__dirname, "fixtures/option-manager/not-a-preset"),
+          ],
+        });
+      }, /While processing: .*option-manager(?:\/|\\\\)not-a-preset\.js/);
     });
   });
 
-  describe("presets", function () {
+  describe("presets", function() {
     function presetTest(name) {
-      it(name, function () {
+      it(name, function() {
         const { options, passes } = manageOptions({
-          "presets": [path.join(__dirname, "fixtures/option-manager/presets", name)],
+          presets: [
+            path.join(__dirname, "fixtures/option-manager/presets", name),
+          ],
         });
 
         assert.equal(true, Array.isArray(options.plugins));
@@ -65,10 +61,16 @@ describe("option-manager", () => {
     }
 
     function presetThrowsTest(name, msg) {
-      it(name, function () {
-        assert.throws(() => manageOptions({
-          "presets": [path.join(__dirname, "fixtures/option-manager/presets", name)],
-        }), msg);
+      it(name, function() {
+        assert.throws(
+          () =>
+            manageOptions({
+              presets: [
+                path.join(__dirname, "fixtures/option-manager/presets", name),
+              ],
+            }),
+          msg,
+        );
       });
     }
 
@@ -77,7 +79,10 @@ describe("option-manager", () => {
     presetTest("es2015_default_function");
     presetTest("es2015_default_object");
 
-    presetThrowsTest("es2015_named", /Must export a default export when using ES6 modules/);
+    presetThrowsTest(
+      "es2015_named",
+      /Must export a default export when using ES6 modules/,
+    );
     presetThrowsTest("es2015_invalid", /Unsupported format: string/);
     presetThrowsTest("es5_invalid", /Unsupported format: string/);
   });
diff --git a/packages/babel-core/test/path.js b/packages/babel-core/test/path.js
index dbc30827c5..7e68d893a0 100644
--- a/packages/babel-core/test/path.js
+++ b/packages/babel-core/test/path.js
@@ -2,152 +2,172 @@ import { transform } from "../lib/index";
 import Plugin from "../lib/config/plugin";
 import chai from "chai";
 
-describe("traversal path", function () {
-  it("replaceWithSourceString", function () {
+describe("traversal path", function() {
+  it("replaceWithSourceString", function() {
     const expectCode = "function foo() {}";
 
     const actualCode = transform(expectCode, {
-      plugins: [new Plugin({
-        visitor: {
-          FunctionDeclaration: function (path) {
-            path.replaceWithSourceString("console.whatever()");
+      plugins: [
+        new Plugin({
+          visitor: {
+            FunctionDeclaration: function(path) {
+              path.replaceWithSourceString("console.whatever()");
+            },
           },
-        },
-      })],
+        }),
+      ],
     }).code;
 
     chai.expect(actualCode).to.be.equal("console.whatever();");
   });
 
-  it("replaceWith (arrow expression body to block statement body)", function () {
+  it("replaceWith (arrow expression body to block statement body)", function() {
     const expectCode = "var fn = () => true;";
 
     const actualCode = transform(expectCode, {
-      plugins: [new Plugin({
-        visitor: {
-          ArrowFunctionExpression: function (path) {
-            path.get("body").replaceWith({
-              type: "BlockStatement",
-              body: [{
-                type: "ReturnStatement",
-                argument: {
-                  type: "BooleanLiteral",
-                  value: true,
-                },
-              }],
-            });
+      plugins: [
+        new Plugin({
+          visitor: {
+            ArrowFunctionExpression: function(path) {
+              path.get("body").replaceWith({
+                type: "BlockStatement",
+                body: [
+                  {
+                    type: "ReturnStatement",
+                    argument: {
+                      type: "BooleanLiteral",
+                      value: true,
+                    },
+                  },
+                ],
+              });
+            },
           },
-        },
-      })],
+        }),
+      ],
     }).code;
 
     chai.expect(actualCode).to.be.equal("var fn = () => {\n  return true;\n};");
   });
 
-  it("replaceWith (arrow block statement body to expression body)", function () {
+  it("replaceWith (arrow block statement body to expression body)", function() {
     const expectCode = "var fn = () => { return true; }";
 
     const actualCode = transform(expectCode, {
-      plugins: [new Plugin({
-        visitor: {
-          ArrowFunctionExpression: function (path) {
-            path.get("body").replaceWith({
-              type: "BooleanLiteral",
-              value: true,
-            });
+      plugins: [
+        new Plugin({
+          visitor: {
+            ArrowFunctionExpression: function(path) {
+              path.get("body").replaceWith({
+                type: "BooleanLiteral",
+                value: true,
+              });
+            },
           },
-        },
-      })],
+        }),
+      ],
     }).code;
 
     chai.expect(actualCode).to.be.equal("var fn = () => true;");
   });
 
-  it("replaceWith (for-in left expression to variable declaration)", function () {
+  it("replaceWith (for-in left expression to variable declaration)", function() {
     const expectCode = "for (KEY in right);";
 
     const actualCode = transform(expectCode, {
-      plugins: [new Plugin({
-        visitor: {
-          ForInStatement: function (path) {
-            path.get("left").replaceWith({
-              type: "VariableDeclaration",
-              kind: "var",
-              declarations: [{
-                type: "VariableDeclarator",
-                id: {
-                  type: "Identifier",
-                  name: "KEY",
-                },
-              }],
-            });
+      plugins: [
+        new Plugin({
+          visitor: {
+            ForInStatement: function(path) {
+              path.get("left").replaceWith({
+                type: "VariableDeclaration",
+                kind: "var",
+                declarations: [
+                  {
+                    type: "VariableDeclarator",
+                    id: {
+                      type: "Identifier",
+                      name: "KEY",
+                    },
+                  },
+                ],
+              });
+            },
           },
-        },
-      })],
+        }),
+      ],
     }).code;
 
     chai.expect(actualCode).to.be.equal("for (var KEY in right);");
   });
 
-  it("replaceWith (for-in left variable declaration to expression)", function () {
+  it("replaceWith (for-in left variable declaration to expression)", function() {
     const expectCode = "for (var KEY in right);";
 
     const actualCode = transform(expectCode, {
-      plugins: [new Plugin({
-        visitor: {
-          ForInStatement: function (path) {
-            path.get("left").replaceWith({
-              type: "Identifier",
-              name: "KEY",
-            });
+      plugins: [
+        new Plugin({
+          visitor: {
+            ForInStatement: function(path) {
+              path.get("left").replaceWith({
+                type: "Identifier",
+                name: "KEY",
+              });
+            },
           },
-        },
-      })],
+        }),
+      ],
     }).code;
 
     chai.expect(actualCode).to.be.equal("for (KEY in right);");
   });
 
-  it("replaceWith (for-loop left expression to variable declaration)", function () {
+  it("replaceWith (for-loop left expression to variable declaration)", function() {
     const expectCode = "for (KEY;;);";
 
     const actualCode = transform(expectCode, {
-      plugins: [new Plugin({
-        visitor: {
-          ForStatement: function (path) {
-            path.get("init").replaceWith({
-              type: "VariableDeclaration",
-              kind: "var",
-              declarations: [{
-                type: "VariableDeclarator",
-                id: {
-                  type: "Identifier",
-                  name: "KEY",
-                },
-              }],
-            });
+      plugins: [
+        new Plugin({
+          visitor: {
+            ForStatement: function(path) {
+              path.get("init").replaceWith({
+                type: "VariableDeclaration",
+                kind: "var",
+                declarations: [
+                  {
+                    type: "VariableDeclarator",
+                    id: {
+                      type: "Identifier",
+                      name: "KEY",
+                    },
+                  },
+                ],
+              });
+            },
           },
-        },
-      })],
+        }),
+      ],
     }).code;
 
     chai.expect(actualCode).to.be.equal("for (var KEY;;);");
   });
 
-  it("replaceWith (for-loop left variable declaration to expression)", function () {
+  it("replaceWith (for-loop left variable declaration to expression)", function() {
     const expectCode = "for (var KEY;;);";
 
     const actualCode = transform(expectCode, {
-      plugins: [new Plugin({
-        visitor: {
-          ForStatement: function (path) {
-            path.get("init").replaceWith({
-              type: "Identifier",
-              name: "KEY",
-            });
+      plugins: [
+        new Plugin({
+          visitor: {
+            ForStatement: function(path) {
+              path.get("init").replaceWith({
+                type: "Identifier",
+                name: "KEY",
+              });
+            },
           },
-        },
-      })],
+        }),
+      ],
     }).code;
 
     chai.expect(actualCode).to.be.equal("for (KEY;;);");
diff --git a/packages/babel-core/test/resolution.js b/packages/babel-core/test/resolution.js
index 3df806b515..cf95e0fc43 100644
--- a/packages/babel-core/test/resolution.js
+++ b/packages/babel-core/test/resolution.js
@@ -2,7 +2,7 @@ import assert from "assert";
 import * as babel from "../lib/index";
 import path from "path";
 
-describe("addon resolution", function () {
+describe("addon resolution", function() {
   const base = path.join(__dirname, "fixtures", "resolution");
 
   beforeEach(function() {
@@ -20,9 +20,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "module:preset",
-      ],
+      presets: ["module:preset"],
     });
   });
 
@@ -32,9 +30,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "module:plugin",
-      ],
+      plugins: ["module:plugin"],
     });
   });
 
@@ -44,9 +40,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "mod",
-      ],
+      presets: ["mod"],
     });
   });
 
@@ -56,9 +50,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "mod",
-      ],
+      plugins: ["mod"],
     });
   });
 
@@ -68,9 +60,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "babel-preset-mod",
-      ],
+      presets: ["babel-preset-mod"],
     });
   });
 
@@ -80,9 +70,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "babel-plugin-mod",
-      ],
+      plugins: ["babel-plugin-mod"],
     });
   });
 
@@ -92,9 +80,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "@babel/foo",
-      ],
+      presets: ["@babel/foo"],
     });
   });
 
@@ -104,9 +90,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "@babel/foo",
-      ],
+      plugins: ["@babel/foo"],
     });
   });
 
@@ -116,9 +100,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "@babel/preset-foo",
-      ],
+      presets: ["@babel/preset-foo"],
     });
   });
 
@@ -128,9 +110,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "@babel/plugin-foo",
-      ],
+      plugins: ["@babel/plugin-foo"],
     });
   });
 
@@ -140,9 +120,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "@foo/mod",
-      ],
+      presets: ["@foo/mod"],
     });
   });
 
@@ -152,9 +130,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "@foo/mod",
-      ],
+      plugins: ["@foo/mod"],
     });
   });
 
@@ -164,9 +140,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "@foo/babel-preset-mod",
-      ],
+      presets: ["@foo/babel-preset-mod"],
     });
   });
 
@@ -176,9 +150,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "@foo/babel-plugin-mod",
-      ],
+      plugins: ["@foo/babel-plugin-mod"],
     });
   });
 
@@ -188,9 +160,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "./dir/preset.js",
-      ],
+      presets: ["./dir/preset.js"],
     });
   });
 
@@ -200,9 +170,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "./dir/plugin.js",
-      ],
+      plugins: ["./dir/plugin.js"],
     });
   });
 
@@ -212,9 +180,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "mod/preset",
-      ],
+      presets: ["mod/preset"],
     });
   });
 
@@ -224,9 +190,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "mod/plugin",
-      ],
+      plugins: ["mod/plugin"],
     });
   });
 
@@ -236,9 +200,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "@foo/mod/preset",
-      ],
+      presets: ["@foo/mod/preset"],
     });
   });
 
@@ -248,9 +210,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "@foo/mod/plugin",
-      ],
+      plugins: ["@foo/mod/plugin"],
     });
   });
 
@@ -260,9 +220,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      presets: [
-        "@babel/mod/preset",
-      ],
+      presets: ["@babel/mod/preset"],
     });
   });
 
@@ -272,9 +230,7 @@ describe("addon resolution", function () {
     babel.transform("", {
       filename: "filename.js",
       babelrc: false,
-      plugins: [
-        "@babel/mod/plugin",
-      ],
+      plugins: ["@babel/mod/plugin"],
     });
   });
 
@@ -285,9 +241,7 @@ describe("addon resolution", function () {
       babel.transform("", {
         filename: "filename.js",
         babelrc: false,
-        presets: [
-          "foo",
-        ],
+        presets: ["foo"],
       });
       // eslint-disable-next-line max-len
     }, /Cannot find module 'babel-preset-foo'.*\n- If you want to resolve "foo", use "module:foo"/);
@@ -300,9 +254,7 @@ describe("addon resolution", function () {
       babel.transform("", {
         filename: "filename.js",
         babelrc: false,
-        plugins: [
-          "foo",
-        ],
+        plugins: ["foo"],
       });
       // eslint-disable-next-line max-len
     }, /Cannot find module 'babel-plugin-foo'.*\n- If you want to resolve "foo", use "module:foo"/);
@@ -315,9 +267,7 @@ describe("addon resolution", function () {
       babel.transform("", {
         filename: "filename.js",
         babelrc: false,
-        presets: [
-          "foo",
-        ],
+        presets: ["foo"],
       });
       // eslint-disable-next-line max-len
     }, /Cannot find module 'babel-preset-foo'.*\n- Did you mean "@babel\/foo"\?/);
@@ -330,9 +280,7 @@ describe("addon resolution", function () {
       babel.transform("", {
         filename: "filename.js",
         babelrc: false,
-        plugins: [
-          "foo",
-        ],
+        plugins: ["foo"],
       });
       // eslint-disable-next-line max-len
     }, /Cannot find module 'babel-plugin-foo'.*\n- Did you mean "@babel\/foo"\?/);
@@ -345,9 +293,7 @@ describe("addon resolution", function () {
       babel.transform("", {
         filename: "filename.js",
         babelrc: false,
-        presets: [
-          "testplugin",
-        ],
+        presets: ["testplugin"],
       });
       // eslint-disable-next-line max-len
     }, /Cannot find module 'babel-preset-testplugin'.*\n- Did you accidentally pass a preset as a plugin\?/);
@@ -360,9 +306,7 @@ describe("addon resolution", function () {
       babel.transform("", {
         filename: "filename.js",
         babelrc: false,
-        plugins: [
-          "testpreset",
-        ],
+        plugins: ["testpreset"],
       });
       // eslint-disable-next-line max-len
     }, /Cannot find module 'babel-plugin-testpreset'.*\n- Did you accidentally pass a plugin as a preset\?/);
@@ -375,9 +319,7 @@ describe("addon resolution", function () {
       babel.transform("", {
         filename: "filename.js",
         babelrc: false,
-        presets: [
-          "foo",
-        ],
+        presets: ["foo"],
       });
     }, /Cannot find module 'babel-preset-foo'/);
   });
@@ -389,9 +331,7 @@ describe("addon resolution", function () {
       babel.transform("", {
         filename: "filename.js",
         babelrc: false,
-        plugins: [
-          "foo",
-        ],
+        plugins: ["foo"],
       });
     }, /Cannot find module 'babel-plugin-foo'/);
   });
diff --git a/packages/babel-generator/src/buffer.js b/packages/babel-generator/src/buffer.js
index 3c53ef666d..ddd57c2051 100644
--- a/packages/babel-generator/src/buffer.js
+++ b/packages/babel-generator/src/buffer.js
@@ -54,7 +54,7 @@ export default class Buffer {
         configurable: true,
         enumerable: true,
         get() {
-          return this.map = map.get();
+          return (this.map = map.get());
         },
         set(value) {
           Object.defineProperty(this, "map", { value, writable: true });
@@ -81,7 +81,11 @@ export default class Buffer {
 
   queue(str: string): void {
     // Drop trailing spaces when a newline is inserted.
-    if (str === "\n") while (this._queue.length > 0 && SPACES_RE.test(this._queue[0][0])) this._queue.shift();
+    if (str === "\n") {
+      while (this._queue.length > 0 && SPACES_RE.test(this._queue[0][0])) {
+        this._queue.shift();
+      }
+    }
 
     const { line, column, filename, identifierName } = this._sourcePosition;
     this._queue.unshift([str, line, column, identifierName, filename]);
@@ -89,13 +93,26 @@ export default class Buffer {
 
   _flush(): void {
     let item;
-    while (item = this._queue.pop()) this._append(...item);
+    while ((item = this._queue.pop())) this._append(...item);
   }
 
-  _append(str: string, line: number, column: number, identifierName: ?string, filename: ?string): void {
+  _append(
+    str: string,
+    line: number,
+    column: number,
+    identifierName: ?string,
+    filename: ?string,
+  ): void {
     // If there the line is ending, adding a new mapping marker is redundant
     if (this._map && str[0] !== "\n") {
-      this._map.mark(this._position.line, this._position.column, line, column, identifierName, filename);
+      this._map.mark(
+        this._position.line,
+        this._position.column,
+        line,
+        column,
+        identifierName,
+        filename,
+      );
     }
 
     this._buf.push(str);
@@ -112,11 +129,15 @@ export default class Buffer {
   }
 
   removeTrailingNewline(): void {
-    if (this._queue.length > 0 && this._queue[0][0] === "\n") this._queue.shift();
+    if (this._queue.length > 0 && this._queue[0][0] === "\n") {
+      this._queue.shift();
+    }
   }
 
   removeLastSemicolon(): void {
-    if (this._queue.length > 0 && this._queue[0][0] === ";") this._queue.shift();
+    if (this._queue.length > 0 && this._queue[0][0] === ";") {
+      this._queue.shift();
+    }
   }
 
   endsWith(suffix: string): boolean {
@@ -133,7 +154,8 @@ export default class Buffer {
       return last === suffix;
     }
 
-    const end = this._last + this._queue.reduce((acc, item) => item[0] + acc, "");
+    const end =
+      this._last + this._queue.reduce((acc, item) => item[0] + acc, "");
     if (suffix.length <= end.length) {
       return end.slice(-suffix.length) === suffix;
     }
@@ -157,10 +179,10 @@ export default class Buffer {
 
     const pos = loc ? loc[prop] : null;
 
-    this._sourcePosition.identifierName = loc && loc.identifierName || null;
+    this._sourcePosition.identifierName = (loc && loc.identifierName) || null;
     this._sourcePosition.line = pos ? pos.line : null;
     this._sourcePosition.column = pos ? pos.column : null;
-    this._sourcePosition.filename = loc && loc.filename || null;
+    this._sourcePosition.filename = (loc && loc.filename) || null;
   }
 
   /**
@@ -190,7 +212,9 @@ export default class Buffer {
     const extra = this._queue.reduce((acc, item) => item[0] + acc, "");
     const lastIndex = extra.lastIndexOf("\n");
 
-    return lastIndex === -1 ? this._position.column + extra.length : (extra.length - 1 - lastIndex);
+    return lastIndex === -1
+      ? this._position.column + extra.length
+      : extra.length - 1 - lastIndex;
   }
 
   getCurrentLine(): number {
diff --git a/packages/babel-generator/src/generators/expressions.js b/packages/babel-generator/src/generators/expressions.js
index 0f1a9d1651..a6b2a4ff90 100644
--- a/packages/babel-generator/src/generators/expressions.js
+++ b/packages/babel-generator/src/generators/expressions.js
@@ -1,9 +1,12 @@
 import * as t from "babel-types";
 import * as n from "../node";
 
-
 export function UnaryExpression(node: Object) {
-  if (node.operator === "void" || node.operator === "delete" || node.operator === "typeof") {
+  if (
+    node.operator === "void" ||
+    node.operator === "delete" ||
+    node.operator === "typeof"
+  ) {
     this.word(node.operator);
     this.space();
   } else {
@@ -51,12 +54,16 @@ export function NewExpression(node: Object, parent: Object) {
   this.word("new");
   this.space();
   this.print(node.callee, node);
-  if (this.format.minified &&
-      node.arguments.length === 0 &&
-      !node.optional &&
-      !t.isCallExpression(parent, { callee: node }) &&
-      !t.isMemberExpression(parent) &&
-      !t.isNewExpression(parent)) return;
+  if (
+    this.format.minified &&
+    node.arguments.length === 0 &&
+    !node.optional &&
+    !t.isCallExpression(parent, { callee: node }) &&
+    !t.isMemberExpression(parent) &&
+    !t.isNewExpression(parent)
+  ) {
+    return;
+  }
 
   if (node.optional) {
     this.token("?.");
@@ -123,7 +130,7 @@ export function Import() {
 }
 
 function buildYieldAwait(keyword: string) {
-  return function (node: Object) {
+  return function(node: Object) {
     this.word(keyword);
 
     if (node.delegate) {
@@ -164,8 +171,10 @@ export function AssignmentPattern(node: Object) {
 export function AssignmentExpression(node: Object, parent: Object) {
   // Somewhere inside a for statement `init` node but doesn't usually
   // needs a paren except for `in` expressions: `for (a in b ? a : b;;)`
-  const parens = this.inForStatementInitCounter && node.operator === "in" &&
-               !n.needsParens(node, parent);
+  const parens =
+    this.inForStatementInitCounter &&
+    node.operator === "in" &&
+    !n.needsParens(node, parent);
 
   if (parens) {
     this.token("(");
diff --git a/packages/babel-generator/src/generators/flow.js b/packages/babel-generator/src/generators/flow.js
index 2425fa15df..1e59e27f95 100644
--- a/packages/babel-generator/src/generators/flow.js
+++ b/packages/babel-generator/src/generators/flow.js
@@ -159,7 +159,10 @@ export function FunctionTypeAnnotation(node: Object, parent: Object) {
   this.token(")");
 
   // this node type is overloaded, not sure why but it makes it EXTREMELY annoying
-  if (parent.type === "ObjectTypeCallProperty" || parent.type === "DeclareFunction") {
+  if (
+    parent.type === "ObjectTypeCallProperty" ||
+    parent.type === "DeclareFunction"
+  ) {
     this.token(":");
   } else {
     this.space();
@@ -183,7 +186,10 @@ export function InterfaceExtends(node: Object) {
   this.print(node.typeParameters, node);
 }
 
-export { InterfaceExtends as ClassImplements, InterfaceExtends as GenericTypeAnnotation };
+export {
+  InterfaceExtends as ClassImplements,
+  InterfaceExtends as GenericTypeAnnotation,
+};
 
 export function _interfaceish(node: Object) {
   this.print(node.id, node);
diff --git a/packages/babel-generator/src/generators/methods.js b/packages/babel-generator/src/generators/methods.js
index 4dcc71a251..48903511db 100644
--- a/packages/babel-generator/src/generators/methods.js
+++ b/packages/babel-generator/src/generators/methods.js
@@ -4,7 +4,7 @@ export function _params(node: Object) {
   this.print(node.typeParameters, node);
   this.token("(");
   this.printList(node.params, node, {
-    iterator: (node) => {
+    iterator: node => {
       if (node.optional) this.token("?");
       this.print(node.typeAnnotation, node);
     },
@@ -79,7 +79,11 @@ export function ArrowFunctionExpression(node: Object) {
 
   const firstParam = node.params[0];
 
-  if (node.params.length === 1 && t.isIdentifier(firstParam) && !hasTypes(node, firstParam)) {
+  if (
+    node.params.length === 1 &&
+    t.isIdentifier(firstParam) &&
+    !hasTypes(node, firstParam)
+  ) {
     this.print(firstParam, node);
   } else {
     this._params(node);
@@ -93,6 +97,11 @@ export function ArrowFunctionExpression(node: Object) {
 }
 
 function hasTypes(node, param) {
-  return node.typeParameters || node.returnType || param.typeAnnotation || param.optional ||
-    param.trailingComments;
+  return (
+    node.typeParameters ||
+    node.returnType ||
+    param.typeAnnotation ||
+    param.optional ||
+    param.trailingComments
+  );
 }
diff --git a/packages/babel-generator/src/generators/modules.js b/packages/babel-generator/src/generators/modules.js
index f5d33b151a..36ae34a4a8 100644
--- a/packages/babel-generator/src/generators/modules.js
+++ b/packages/babel-generator/src/generators/modules.js
@@ -91,7 +91,10 @@ function ExportDeclaration(node: Object) {
     let hasSpecial = false;
     while (true) {
       const first = specifiers[0];
-      if (t.isExportDefaultSpecifier(first) || t.isExportNamespaceSpecifier(first)) {
+      if (
+        t.isExportDefaultSpecifier(first) ||
+        t.isExportNamespaceSpecifier(first)
+      ) {
         hasSpecial = true;
         this.print(specifiers.shift(), node);
         if (specifiers.length) {
@@ -138,7 +141,10 @@ export function ImportDeclaration(node: Object) {
     // print "special" specifiers first
     while (true) {
       const first = specifiers[0];
-      if (t.isImportDefaultSpecifier(first) || t.isImportNamespaceSpecifier(first)) {
+      if (
+        t.isImportDefaultSpecifier(first) ||
+        t.isImportNamespaceSpecifier(first)
+      ) {
         this.print(specifiers.shift(), node);
         if (specifiers.length) {
           this.token(",");
diff --git a/packages/babel-generator/src/generators/statements.js b/packages/babel-generator/src/generators/statements.js
index 8aee284a6d..4929659874 100644
--- a/packages/babel-generator/src/generators/statements.js
+++ b/packages/babel-generator/src/generators/statements.js
@@ -17,7 +17,8 @@ export function IfStatement(node: Object) {
   this.token(")");
   this.space();
 
-  const needsBlock = node.alternate && t.isIfStatement(getLastStatement(node.consequent));
+  const needsBlock =
+    node.alternate && t.isIfStatement(getLastStatement(node.consequent));
   if (needsBlock) {
     this.token("{");
     this.newline();
@@ -80,8 +81,8 @@ export function WhileStatement(node: Object) {
   this.printBlock(node);
 }
 
-const buildForXStatement = function (op) {
-  return function (node: Object) {
+const buildForXStatement = function(op) {
+  return function(node: Object) {
     this.word("for");
     this.space();
     if (op === "of" && node.await) {
@@ -116,7 +117,7 @@ export function DoWhileStatement(node: Object) {
 }
 
 function buildLabelStatement(prefix, key = "label") {
-  return function (node: Object) {
+  return function(node: Object) {
     this.word(prefix);
 
     const label = node[key];
@@ -261,7 +262,10 @@ export function VariableDeclaration(node: Object, parent: Object) {
 
   let separator;
   if (hasInits) {
-    separator = node.kind === "const" ? constDeclarationIndent : variableDeclarationIndent;
+    separator =
+      node.kind === "const"
+        ? constDeclarationIndent
+        : variableDeclarationIndent;
   }
 
   //
diff --git a/packages/babel-generator/src/generators/types.js b/packages/babel-generator/src/generators/types.js
index 9895324062..35724213d9 100644
--- a/packages/babel-generator/src/generators/types.js
+++ b/packages/babel-generator/src/generators/types.js
@@ -10,9 +10,7 @@ export function RestElement(node: Object) {
   this.print(node.argument, node);
 }
 
-export {
-  RestElement as SpreadElement,
-};
+export { RestElement as SpreadElement };
 
 export function ObjectExpression(node: Object) {
   const props = node.properties;
@@ -45,8 +43,11 @@ export function ObjectProperty(node: Object) {
     this.token("]");
   } else {
     // print `({ foo: foo = 5 } = {})` as `({ foo = 5 } = {});`
-    if (t.isAssignmentPattern(node.value) && t.isIdentifier(node.key) &&
-      node.key.name === node.value.left.name) {
+    if (
+      t.isAssignmentPattern(node.value) &&
+      t.isIdentifier(node.key) &&
+      node.key.name === node.value.left.name
+    ) {
       this.print(node.value, node);
       return;
     }
@@ -54,10 +55,12 @@ export function ObjectProperty(node: Object) {
     this.print(node.key, node);
 
     // shorthand!
-    if (node.shorthand &&
+    if (
+      node.shorthand &&
       (t.isIdentifier(node.key) &&
-       t.isIdentifier(node.value) &&
-       node.key.name === node.value.name)) {
+        t.isIdentifier(node.value) &&
+        node.key.name === node.value.name)
+    ) {
       return;
     }
   }
@@ -111,7 +114,7 @@ export function NumericLiteral(node: Object) {
   const raw = this.getPossibleRaw(node);
   const value = node.value + "";
   if (raw == null) {
-    this.number(value);  // normalize
+    this.number(value); // normalize
   } else if (this.format.minified) {
     this.number(raw.length < value.length ? raw : value);
   } else {
diff --git a/packages/babel-generator/src/index.js b/packages/babel-generator/src/index.js
index cc8511c935..ef0012053e 100644
--- a/packages/babel-generator/src/index.js
+++ b/packages/babel-generator/src/index.js
@@ -61,17 +61,23 @@ function normalizeOptions(code, opts): Format {
   if (format.minified) {
     format.compact = true;
 
-    format.shouldPrintComment = format.shouldPrintComment || (() => format.comments);
+    format.shouldPrintComment =
+      format.shouldPrintComment || (() => format.comments);
   } else {
-    format.shouldPrintComment = format.shouldPrintComment || ((value) => format.comments ||
-      (value.indexOf("@license") >= 0 || value.indexOf("@preserve") >= 0));
+    format.shouldPrintComment =
+      format.shouldPrintComment ||
+      (value =>
+        format.comments ||
+        (value.indexOf("@license") >= 0 || value.indexOf("@preserve") >= 0));
   }
 
   if (format.compact === "auto") {
     format.compact = code.length > 500_000; // 500KB
 
     if (format.compact) {
-      console.error("[BABEL] " + messages.get("codeGeneratorDeopt", opts.filename, "500KB"));
+      console.error(
+        "[BABEL] " + messages.get("codeGeneratorDeopt", opts.filename, "500KB"),
+      );
     }
   }
 
@@ -97,7 +103,7 @@ export class CodeGenerator {
   }
 }
 
-export default function (ast: Object, opts: Object, code: string): Object {
+export default function(ast: Object, opts: Object, code: string): Object {
   const gen = new Generator(ast, opts, code);
   return gen.generate();
 }
diff --git a/packages/babel-generator/src/node/index.js b/packages/babel-generator/src/node/index.js
index c3a17cea6c..c7fb0026a1 100644
--- a/packages/babel-generator/src/node/index.js
+++ b/packages/babel-generator/src/node/index.js
@@ -7,15 +7,16 @@ function expandAliases(obj) {
 
   function add(type, func) {
     const fn = newObj[type];
-    newObj[type] = fn ? function(node, parent, stack) {
-      const result = fn(node, parent, stack);
+    newObj[type] = fn
+      ? function(node, parent, stack) {
+          const result = fn(node, parent, stack);
 
-      return result == null ? func(node, parent, stack) : result;
-    } : func;
+          return result == null ? func(node, parent, stack) : result;
+        }
+      : func;
   }
 
   for (const type of Object.keys(obj)) {
-
     const aliases = t.FLIPPED_ALIAS_KEYS[type];
     if (aliases) {
       for (const alias of aliases) {
@@ -46,8 +47,10 @@ function isOrHasCallExpression(node) {
   }
 
   if (t.isMemberExpression(node)) {
-    return isOrHasCallExpression(node.object) ||
-      (!node.computed && isOrHasCallExpression(node.property));
+    return (
+      isOrHasCallExpression(node.object) ||
+      (!node.computed && isOrHasCallExpression(node.property))
+    );
   } else {
     return false;
   }
diff --git a/packages/babel-generator/src/node/parentheses.js b/packages/babel-generator/src/node/parentheses.js
index 6879417c38..2f4326ec5e 100644
--- a/packages/babel-generator/src/node/parentheses.js
+++ b/packages/babel-generator/src/node/parentheses.js
@@ -38,11 +38,19 @@ export function UpdateExpression(node: Object, parent: Object): boolean {
   return t.isMemberExpression(parent) && parent.object === node;
 }
 
-export function ObjectExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
+export function ObjectExpression(
+  node: Object,
+  parent: Object,
+  printStack: Array<Object>,
+): boolean {
   return isFirstInStatement(printStack, { considerArrow: true });
 }
 
-export function DoExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
+export function DoExpression(
+  node: Object,
+  parent: Object,
+  printStack: Array<Object>,
+): boolean {
   return isFirstInStatement(printStack);
 }
 
@@ -55,7 +63,8 @@ export function Binary(node: Object, parent: Object): boolean {
   }
 
   if (
-    ((t.isCallExpression(parent) || t.isNewExpression(parent)) && parent.callee === node) ||
+    ((t.isCallExpression(parent) || t.isNewExpression(parent)) &&
+      parent.callee === node) ||
     t.isUnaryLike(parent) ||
     (t.isMemberExpression(parent) && parent.object === node) ||
     t.isAwaitExpression(parent)
@@ -72,7 +81,9 @@ export function Binary(node: Object, parent: Object): boolean {
 
     if (
       // Logical expressions with the same precedence don't need parens.
-      (parentPos === nodePos && parent.right === node && !t.isLogicalExpression(parent)) ||
+      (parentPos === nodePos &&
+        parent.right === node &&
+        !t.isLogicalExpression(parent)) ||
       parentPos > nodePos
     ) {
       return true;
@@ -85,11 +96,13 @@ export function Binary(node: Object, parent: Object): boolean {
 export function BinaryExpression(node: Object, parent: Object): boolean {
   // let i = (1 in []);
   // for ((1 in []);;);
-  return node.operator === "in" && (t.isVariableDeclarator(parent) || t.isFor(parent));
+  return (
+    node.operator === "in" &&
+    (t.isVariableDeclarator(parent) || t.isFor(parent))
+  );
 }
 
 export function SequenceExpression(node: Object, parent: Object): boolean {
-
   if (
     // Although parentheses wouldn"t hurt around sequence
     // expressions in the head of for loops, traditional style
@@ -113,29 +126,40 @@ export function SequenceExpression(node: Object, parent: Object): boolean {
 }
 
 export function YieldExpression(node: Object, parent: Object): boolean {
-  return t.isBinary(parent) ||
-         t.isUnaryLike(parent) ||
-         t.isCallExpression(parent) ||
-         t.isMemberExpression(parent) ||
-         t.isNewExpression(parent) ||
-         (t.isConditionalExpression(parent) && node === parent.test);
-
+  return (
+    t.isBinary(parent) ||
+    t.isUnaryLike(parent) ||
+    t.isCallExpression(parent) ||
+    t.isMemberExpression(parent) ||
+    t.isNewExpression(parent) ||
+    (t.isConditionalExpression(parent) && node === parent.test)
+  );
 }
 
 export { YieldExpression as AwaitExpression };
 
-export function ClassExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
+export function ClassExpression(
+  node: Object,
+  parent: Object,
+  printStack: Array<Object>,
+): boolean {
   return isFirstInStatement(printStack, { considerDefaultExports: true });
 }
 
 export function UnaryLike(node: Object, parent: Object): boolean {
-  return t.isMemberExpression(parent, { object: node }) ||
-         t.isCallExpression(parent, { callee: node }) ||
-         t.isNewExpression(parent, { callee: node }) ||
-         t.isBinaryExpression(parent, { operator: "**", left: node });
+  return (
+    t.isMemberExpression(parent, { object: node }) ||
+    t.isCallExpression(parent, { callee: node }) ||
+    t.isNewExpression(parent, { callee: node }) ||
+    t.isBinaryExpression(parent, { operator: "**", left: node })
+  );
 }
 
-export function FunctionExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
+export function FunctionExpression(
+  node: Object,
+  parent: Object,
+  printStack: Array<Object>,
+): boolean {
   return isFirstInStatement(printStack, { considerDefaultExports: true });
 }
 
@@ -167,10 +191,10 @@ export function AssignmentExpression(node: Object): boolean {
 
 // Walk up the print stack to deterimine if our node can come first
 // in statement.
-function isFirstInStatement(printStack: Array<Object>, {
-    considerArrow = false,
-    considerDefaultExports = false,
-  } = {}): boolean {
+function isFirstInStatement(
+  printStack: Array<Object>,
+  { considerArrow = false, considerDefaultExports = false } = {},
+): boolean {
   let i = printStack.length - 1;
   let node = printStack[i];
   i--;
@@ -179,8 +203,9 @@ function isFirstInStatement(printStack: Array<Object>, {
     if (
       t.isExpressionStatement(parent, { expression: node }) ||
       t.isTaggedTemplateExpression(parent) ||
-      considerDefaultExports && t.isExportDefaultDeclaration(parent, { declaration: node }) ||
-      considerArrow && t.isArrowFunctionExpression(parent, { body: node })
+      (considerDefaultExports &&
+        t.isExportDefaultDeclaration(parent, { declaration: node })) ||
+      (considerArrow && t.isArrowFunctionExpression(parent, { body: node }))
     ) {
       return true;
     }
diff --git a/packages/babel-generator/src/node/whitespace.js b/packages/babel-generator/src/node/whitespace.js
index 11dce425e6..ca8406af32 100644
--- a/packages/babel-generator/src/node/whitespace.js
+++ b/packages/babel-generator/src/node/whitespace.js
@@ -3,7 +3,7 @@ import * as t from "babel-types";
 
 type WhitespaceObject = {
   before?: boolean,
-  after?: boolean
+  after?: boolean,
 };
 
 /**
@@ -45,15 +45,22 @@ function isHelper(node) {
   } else if (t.isCallExpression(node)) {
     return isHelper(node.callee);
   } else if (t.isBinary(node) || t.isAssignmentExpression(node)) {
-    return (t.isIdentifier(node.left) && isHelper(node.left)) || isHelper(node.right);
+    return (
+      (t.isIdentifier(node.left) && isHelper(node.left)) || isHelper(node.right)
+    );
   } else {
     return false;
   }
 }
 
 function isType(node) {
-  return t.isLiteral(node) || t.isObjectExpression(node) || t.isArrayExpression(node) ||
-         t.isIdentifier(node) || t.isMemberExpression(node);
+  return (
+    t.isLiteral(node) ||
+    t.isObjectExpression(node) ||
+    t.isArrayExpression(node) ||
+    t.isIdentifier(node) ||
+    t.isMemberExpression(node)
+  );
 }
 
 /**
@@ -61,7 +68,6 @@ function isType(node) {
  */
 
 export const nodes = {
-
   /**
    * Test if AssignmentExpression needs whitespace.
    */
@@ -164,9 +170,10 @@ export const nodes = {
  * Test if Property needs whitespace.
  */
 
-nodes.ObjectProperty =
-nodes.ObjectTypeProperty =
-nodes.ObjectMethod = function (node: Object, parent): ?WhitespaceObject {
+nodes.ObjectProperty = nodes.ObjectTypeProperty = nodes.ObjectMethod = function(
+  node: Object,
+  parent,
+): ?WhitespaceObject {
   if (parent.properties[0] === node) {
     return {
       before: true,
@@ -179,7 +186,6 @@ nodes.ObjectMethod = function (node: Object, parent): ?WhitespaceObject {
  */
 
 export const list = {
-
   /**
    * Return VariableDeclaration declarations init properties.
    */
@@ -216,12 +222,12 @@ export const list = {
   ["LabeledStatement", true],
   ["SwitchStatement", true],
   ["TryStatement", true],
-].forEach(function ([type, amounts]) {
+].forEach(function([type, amounts]) {
   if (typeof amounts === "boolean") {
     amounts = { after: amounts, before: amounts };
   }
-  [type].concat(t.FLIPPED_ALIAS_KEYS[type] || []).forEach(function (type) {
-    nodes[type] = function () {
+  [type].concat(t.FLIPPED_ALIAS_KEYS[type] || []).forEach(function(type) {
+    nodes[type] = function() {
       return amounts;
     };
   });
diff --git a/packages/babel-generator/src/printer.js b/packages/babel-generator/src/printer.js
index b7b319293c..a6fa7bc3fb 100644
--- a/packages/babel-generator/src/printer.js
+++ b/packages/babel-generator/src/printer.js
@@ -14,21 +14,21 @@ const ZERO_DECIMAL_INTEGER = /\.0+$/;
 const NON_DECIMAL_LITERAL = /^0[box]/;
 
 export type Format = {
-  shouldPrintComment: (comment: string) => boolean;
-  retainLines: boolean;
-  retainFunctionParens: boolean;
-  comments: boolean;
-  auxiliaryCommentBefore: string;
-  auxiliaryCommentAfter: string;
-  compact: boolean | "auto";
-  minified: boolean;
-  quotes: "single" | "double";
-  concise: boolean;
+  shouldPrintComment: (comment: string) => boolean,
+  retainLines: boolean,
+  retainFunctionParens: boolean,
+  comments: boolean,
+  auxiliaryCommentBefore: string,
+  auxiliaryCommentAfter: string,
+  compact: boolean | "auto",
+  minified: boolean,
+  quotes: "single" | "double",
+  concise: boolean,
   indent: {
-    adjustMultilineComment: boolean;
-    style: string;
-    base: number;
-  }
+    adjustMultilineComment: boolean,
+    style: string,
+    base: number,
+  },
 };
 
 export default class Printer {
@@ -107,7 +107,10 @@ export default class Printer {
   space(force: boolean = false): void {
     if (this.format.compact) return;
 
-    if ((this._buf.hasContent() && !this.endsWith(" ") && !this.endsWith("\n")) || force) {
+    if (
+      (this._buf.hasContent() && !this.endsWith(" ") && !this.endsWith("\n")) ||
+      force
+    ) {
       this._space();
     }
   }
@@ -149,14 +152,14 @@ export default class Printer {
   token(str: string): void {
     // space is mandatory to avoid outputting <!--
     // http://javascript.spec.whatwg.org/#comment-syntax
-    if ((str === "--" && this.endsWith("!")) ||
-
+    if (
+      (str === "--" && this.endsWith("!")) ||
       // Need spaces for operators of the same kind to avoid: `a+++b`
       (str[0] === "+" && this.endsWith("+")) ||
       (str[0] === "-" && this.endsWith("-")) ||
-
       // Needs spaces to avoid changing '34' to '34.', which would still be a valid number.
-      (str[0] === "." && this._endsWithInteger)) {
+      (str[0] === "." && this._endsWithInteger)
+    ) {
       this._space();
     }
 
@@ -294,9 +297,9 @@ export default class Printer {
    */
 
   startTerminatorless(): Object {
-    return this._parenPushNewlineState = {
+    return (this._parenPushNewlineState = {
       printed: false,
-    };
+    });
   }
 
   /**
@@ -322,7 +325,11 @@ export default class Printer {
     const printMethod = this[node.type];
     if (!printMethod) {
       // eslint-disable-next-line max-len
-      throw new ReferenceError(`unknown node of type ${JSON.stringify(node.type)} with constructor ${JSON.stringify(node && node.constructor.name)}`);
+      throw new ReferenceError(
+        `unknown node of type ${JSON.stringify(
+          node.type,
+        )} with constructor ${JSON.stringify(node && node.constructor.name)}`,
+      );
     }
 
     this._printStack.push(node);
@@ -335,7 +342,8 @@ export default class Printer {
     if (
       this.format.retainFunctionParens &&
       node.type === "FunctionExpression" &&
-      node.extra && node.extra.parenthesized
+      node.extra &&
+      node.extra.parenthesized
     ) {
       needsParens = true;
     }
@@ -343,7 +351,7 @@ export default class Printer {
 
     this._printLeadingComments(node, parent);
 
-    const loc = (t.isProgram(node) || t.isFile(node)) ? null : node.loc;
+    const loc = t.isProgram(node) || t.isFile(node) ? null : node.loc;
     this.withSource("start", loc, () => {
       this[node.type](node, parent);
     });
@@ -392,7 +400,12 @@ export default class Printer {
 
   getPossibleRaw(node) {
     const extra = node.extra;
-    if (extra && extra.raw != null && extra.rawValue != null && node.value === extra.rawValue) {
+    if (
+      extra &&
+      extra.raw != null &&
+      extra.rawValue != null &&
+      node.value === extra.rawValue
+    ) {
       return extra.raw;
     }
   }
@@ -490,14 +503,24 @@ export default class Printer {
       // user node
       if (leading) {
         const comments = node.leadingComments;
-        const comment = comments && find(comments, (comment) =>
-          !!comment.loc && this.format.shouldPrintComment(comment.value));
+        const comment =
+          comments &&
+          find(
+            comments,
+            comment =>
+              !!comment.loc && this.format.shouldPrintComment(comment.value),
+          );
 
         lines = this._whitespace.getNewlinesBefore(comment || node);
       } else {
         const comments = node.trailingComments;
-        const comment = comments && findLast(comments, (comment) =>
-          !!comment.loc && this.format.shouldPrintComment(comment.value));
+        const comment =
+          comments &&
+          findLast(
+            comments,
+            comment =>
+              !!comment.loc && this.format.shouldPrintComment(comment.value),
+          );
 
         lines = this._whitespace.getNewlinesAfter(comment || node);
       }
@@ -520,7 +543,9 @@ export default class Printer {
   _getComments(leading, node) {
     // Note, we use a boolean flag here instead of passing in the attribute name as it is faster
     // because this is called extremely frequently.
-    return (node && (leading ? node.leadingComments : node.trailingComments)) || [];
+    return (
+      (node && (leading ? node.leadingComments : node.trailingComments)) || []
+    );
   }
 
   _printComment(comment) {
@@ -539,21 +564,32 @@ export default class Printer {
     }
 
     // whitespace before
-    this.newline(this._whitespace ? this._whitespace.getNewlinesBefore(comment) : 0);
+    this.newline(
+      this._whitespace ? this._whitespace.getNewlinesBefore(comment) : 0,
+    );
 
     if (!this.endsWith("[") && !this.endsWith("{")) this.space();
 
-    let val = comment.type === "CommentLine" ? `//${comment.value}\n` : `/*${comment.value}*/`;
+    let val =
+      comment.type === "CommentLine"
+        ? `//${comment.value}\n`
+        : `/*${comment.value}*/`;
 
     //
-    if (comment.type === "CommentBlock" && this.format.indent.adjustMultilineComment) {
+    if (
+      comment.type === "CommentBlock" &&
+      this.format.indent.adjustMultilineComment
+    ) {
       const offset = comment.loc && comment.loc.start.column;
       if (offset) {
         const newlineRegex = new RegExp("\\n\\s{1," + offset + "}", "g");
         val = val.replace(newlineRegex, "\n");
       }
 
-      const indentSize = Math.max(this._getIndent().length, this._buf.getCurrentColumn());
+      const indentSize = Math.max(
+        this._getIndent().length,
+        this._buf.getCurrentColumn(),
+      );
       val = val.replace(/\n(?!$)/g, `\n${repeat(" ", indentSize)}`);
     }
 
@@ -565,9 +601,11 @@ export default class Printer {
     });
 
     // whitespace after
-    this.newline((this._whitespace ? this._whitespace.getNewlinesAfter(comment) : 0) +
-      // Subtract one to account for the line force-added above.
-      (comment.type === "CommentLine" ? -1 : 0));
+    this.newline(
+      (this._whitespace ? this._whitespace.getNewlinesAfter(comment) : 0) +
+        // Subtract one to account for the line force-added above.
+        (comment.type === "CommentLine" ? -1 : 0),
+    );
   }
 
   _printComments(comments?: Array<Object>) {
diff --git a/packages/babel-generator/src/source-map.js b/packages/babel-generator/src/source-map.js
index 4388debc89..c2a4164282 100644
--- a/packages/babel-generator/src/source-map.js
+++ b/packages/babel-generator/src/source-map.js
@@ -18,16 +18,16 @@ export default class SourceMap {
 
   get() {
     if (!this._cachedMap) {
-      const map = this._cachedMap = new sourceMap.SourceMapGenerator({
+      const map = (this._cachedMap = new sourceMap.SourceMapGenerator({
         file: this._opts.sourceMapTarget,
         sourceRoot: this._opts.sourceRoot,
-      });
+      }));
 
       const code = this._code;
       if (typeof code === "string") {
         map.setSourceContent(this._opts.sourceFileName, code);
       } else if (typeof code === "object") {
-        Object.keys(code).forEach((sourceFileName) => {
+        Object.keys(code).forEach(sourceFileName => {
           map.setSourceContent(sourceFileName, code[sourceFileName]);
         });
       }
@@ -60,8 +60,11 @@ export default class SourceMap {
 
     // If this mapping points to the same source location as the last one, we can ignore it since
     // the previous one covers it.
-    if (this._lastGenLine === generatedLine && this._lastSourceLine === line &&
-      this._lastSourceColumn === column) {
+    if (
+      this._lastGenLine === generatedLine &&
+      this._lastSourceLine === line &&
+      this._lastSourceColumn === column
+    ) {
       return;
     }
 
@@ -80,10 +83,13 @@ export default class SourceMap {
         column: generatedColumn,
       },
       source: line == null ? undefined : filename || this._opts.sourceFileName,
-      original: line == null ? undefined : {
-        line: line,
-        column: column,
-      },
+      original:
+        line == null
+          ? undefined
+          : {
+              line: line,
+              column: column,
+            },
     });
   }
 }
diff --git a/packages/babel-generator/src/whitespace.js b/packages/babel-generator/src/whitespace.js
index aabe0d123a..dec0665184 100644
--- a/packages/babel-generator/src/whitespace.js
+++ b/packages/babel-generator/src/whitespace.js
@@ -17,7 +17,11 @@ export default class Whitespace {
     let endToken;
     const tokens = this.tokens;
 
-    let index = this._findToken((token) => token.start - node.start, 0, tokens.length);
+    let index = this._findToken(
+      token => token.start - node.start,
+      0,
+      tokens.length,
+    );
     if (index >= 0) {
       while (index && node.start === tokens[index - 1].start) --index;
       startToken = tokens[index - 1];
@@ -36,7 +40,11 @@ export default class Whitespace {
     let endToken;
     const tokens = this.tokens;
 
-    let index = this._findToken((token) => token.end - node.end, 0, tokens.length);
+    let index = this._findToken(
+      token => token.end - node.end,
+      0,
+      tokens.length,
+    );
     if (index >= 0) {
       while (index && node.end === tokens[index - 1].end) --index;
       startToken = tokens[index];
diff --git a/packages/babel-generator/test/index.js b/packages/babel-generator/test/index.js
index 54c107bcd5..edc0901b39 100644
--- a/packages/babel-generator/test/index.js
+++ b/packages/babel-generator/test/index.js
@@ -9,125 +9,164 @@ import fs from "fs";
 import path from "path";
 import fixtures from "babel-helper-fixtures";
 
-describe("generation", function () {
-  it("completeness", function () {
-    Object.keys(t.VISITOR_KEYS).forEach(function (type) {
+describe("generation", function() {
+  it("completeness", function() {
+    Object.keys(t.VISITOR_KEYS).forEach(function(type) {
       assert.ok(!!Printer.prototype[type], type + " should exist");
     });
 
-    Object.keys(Printer.prototype).forEach(function (type) {
+    Object.keys(Printer.prototype).forEach(function(type) {
       if (!/[A-Z]/.test(type[0])) return;
       assert.ok(t.VISITOR_KEYS[type], type + " should not exist");
     });
   });
 
-  it("multiple sources", function () {
+  it("multiple sources", function() {
     const sources = {
       "a.js": "function hi (msg) { console.log(msg); }\n",
       "b.js": "hi('hello');\n",
     };
-    const parsed = Object.keys(sources).reduce(function (_parsed, filename) {
-      _parsed[filename] = parse(sources[filename], { sourceFilename: filename });
+    const parsed = Object.keys(sources).reduce(function(_parsed, filename) {
+      _parsed[filename] = parse(sources[filename], {
+        sourceFilename: filename,
+      });
       return _parsed;
     }, {});
 
     const combinedAst = {
-      "type": "File",
-      "program": {
-        "type": "Program",
-        "sourceType": "module",
-        "body": [].concat(parsed["a.js"].program.body, parsed["b.js"].program.body),
+      type: "File",
+      program: {
+        type: "Program",
+        sourceType: "module",
+        body: [].concat(
+          parsed["a.js"].program.body,
+          parsed["b.js"].program.body,
+        ),
       },
     };
 
     const generated = generate(combinedAst, { sourceMaps: true }, sources);
 
-    chai.expect(generated.map).to.deep.equal({
-      version: 3,
-      sources: [ "a.js", "b.js" ],
-      mappings: "AAAA,SAASA,EAAT,CAAaC,GAAb,EAAkB;AAAEC,UAAQC,GAAR,CAAYF,GAAZ;AAAmB;;ACAvCD,GAAG,OAAH",
-      names: [
-        "hi",
-        "msg",
-        "console",
-        "log",
-      ],
-      sourcesContent: [
-        "function hi (msg) { console.log(msg); }\n",
-        "hi('hello');\n",
-      ],
-    }, "sourcemap was incorrectly generated");
-
-    chai.expect(generated.rawMappings).to.deep.equal([
-      { name: undefined,
-        generated: { line: 1, column: 0 },
-        source: "a.js",
-        original: { line: 1, column: 0 } },
-      { name: "hi",
-        generated: { line: 1, column: 9 },
-        source: "a.js",
-        original: { line: 1, column: 9 } },
-      { name: undefined,
-        generated: { line: 1, column: 11 },
-        source: "a.js",
-        original: { line: 1, column: 0 } },
-      { name: "msg",
-        generated: { line: 1, column: 12 },
-        source: "a.js",
-        original: { line: 1, column: 13 } },
-      { name: undefined,
-        generated: { line: 1, column: 15 },
-        source: "a.js",
-        original: { line: 1, column: 0 } },
-      { name: undefined,
-        generated: { line: 1, column: 17 },
-        source: "a.js",
-        original: { line: 1, column: 18 } },
-      { name: "console",
-        generated: { line: 2, column: 0 },
-        source: "a.js",
-        original: { line: 1, column: 20 } },
-      { name: "log",
-        generated: { line: 2, column: 10 },
-        source: "a.js",
-        original: { line: 1, column: 28 } },
-      { name: undefined,
-        generated: { line: 2, column: 13 },
-        source: "a.js",
-        original: { line: 1, column: 20 } },
-      { name: "msg",
-        generated: { line: 2, column: 14 },
-        source: "a.js",
-        original: { line: 1, column: 32 } },
-      { name: undefined,
-        generated: { line: 2, column: 17 },
-        source: "a.js",
-        original: { line: 1, column: 20 } },
-      { name: undefined,
-        generated: { line: 3, column: 0 },
-        source: "a.js",
-        original: { line: 1, column: 39 } },
-      { name: "hi",
-        generated: { line: 5, column: 0 },
-        source: "b.js",
-        original: { line: 1, column: 0 } },
-      { name: undefined,
-        generated: { line: 5, column: 3 },
-        source: "b.js",
-        original: { line: 1, column: 3 } },
-      { name: undefined,
-        generated: { line: 5, column: 10 },
-        source: "b.js",
-        original: { line: 1, column: 0 } },
-    ], "raw mappings were incorrectly generated");
-
-    chai.expect(generated.code).to.equal(
-      "function hi(msg) {\n  console.log(msg);\n}\n\nhi('hello');",
-      "code was incorrectly generated"
+    chai.expect(generated.map).to.deep.equal(
+      {
+        version: 3,
+        sources: ["a.js", "b.js"],
+        mappings:
+          "AAAA,SAASA,EAAT,CAAaC,GAAb,EAAkB;AAAEC,UAAQC,GAAR,CAAYF,GAAZ;AAAmB;;ACAvCD,GAAG,OAAH",
+        names: ["hi", "msg", "console", "log"],
+        sourcesContent: [
+          "function hi (msg) { console.log(msg); }\n",
+          "hi('hello');\n",
+        ],
+      },
+      "sourcemap was incorrectly generated",
     );
+
+    chai.expect(generated.rawMappings).to.deep.equal(
+      [
+        {
+          name: undefined,
+          generated: { line: 1, column: 0 },
+          source: "a.js",
+          original: { line: 1, column: 0 },
+        },
+        {
+          name: "hi",
+          generated: { line: 1, column: 9 },
+          source: "a.js",
+          original: { line: 1, column: 9 },
+        },
+        {
+          name: undefined,
+          generated: { line: 1, column: 11 },
+          source: "a.js",
+          original: { line: 1, column: 0 },
+        },
+        {
+          name: "msg",
+          generated: { line: 1, column: 12 },
+          source: "a.js",
+          original: { line: 1, column: 13 },
+        },
+        {
+          name: undefined,
+          generated: { line: 1, column: 15 },
+          source: "a.js",
+          original: { line: 1, column: 0 },
+        },
+        {
+          name: undefined,
+          generated: { line: 1, column: 17 },
+          source: "a.js",
+          original: { line: 1, column: 18 },
+        },
+        {
+          name: "console",
+          generated: { line: 2, column: 0 },
+          source: "a.js",
+          original: { line: 1, column: 20 },
+        },
+        {
+          name: "log",
+          generated: { line: 2, column: 10 },
+          source: "a.js",
+          original: { line: 1, column: 28 },
+        },
+        {
+          name: undefined,
+          generated: { line: 2, column: 13 },
+          source: "a.js",
+          original: { line: 1, column: 20 },
+        },
+        {
+          name: "msg",
+          generated: { line: 2, column: 14 },
+          source: "a.js",
+          original: { line: 1, column: 32 },
+        },
+        {
+          name: undefined,
+          generated: { line: 2, column: 17 },
+          source: "a.js",
+          original: { line: 1, column: 20 },
+        },
+        {
+          name: undefined,
+          generated: { line: 3, column: 0 },
+          source: "a.js",
+          original: { line: 1, column: 39 },
+        },
+        {
+          name: "hi",
+          generated: { line: 5, column: 0 },
+          source: "b.js",
+          original: { line: 1, column: 0 },
+        },
+        {
+          name: undefined,
+          generated: { line: 5, column: 3 },
+          source: "b.js",
+          original: { line: 1, column: 3 },
+        },
+        {
+          name: undefined,
+          generated: { line: 5, column: 10 },
+          source: "b.js",
+          original: { line: 1, column: 0 },
+        },
+      ],
+      "raw mappings were incorrectly generated",
+    );
+
+    chai
+      .expect(generated.code)
+      .to.equal(
+        "function hi(msg) {\n  console.log(msg);\n}\n\nhi('hello');",
+        "code was incorrectly generated",
+      );
   });
 
-  it("identifierName", function () {
+  it("identifierName", function() {
     const code = "function foo() { bar; }\n";
 
     const ast = parse(code, { filename: "inline" }).program;
@@ -141,51 +180,75 @@ describe("generation", function () {
     id2.name += "2";
     id2.loc.identiferName = "bar";
 
-    const generated = generate(ast, {
-      filename: "inline",
-      sourceFileName: "inline",
-      sourceMaps: true,
-    }, code);
-
-    chai.expect(generated.map).to.deep.equal({
-      version: 3,
-      sources: ["inline"],
-      names: ["foo", "bar" ],
-      mappings: "AAAA,SAASA,IAAT,GAAe;AAAEC;AAAM",
-      sourcesContent: [ "function foo() { bar; }\n" ],
-    }, "sourcemap was incorrectly generated");
-
-    chai.expect(generated.rawMappings).to.deep.equal([
-      { name: undefined,
-        generated: { line: 1, column: 0 },
-        source: "inline",
-        original: { line: 1, column: 0 } },
-      { name: "foo",
-        generated: { line: 1, column: 9 },
-        source: "inline",
-        original: { line: 1, column: 9 } },
-      { name: undefined,
-        generated: { line: 1, column: 13 },
-        source: "inline",
-        original: { line: 1, column: 0 } },
-      { name: undefined,
-        generated: { line: 1, column: 16 },
-        source: "inline",
-        original: { line: 1, column: 15 } },
-      { name: "bar",
-        generated: { line: 2, column: 0 },
-        source: "inline",
-        original: { line: 1, column: 17 } },
-      { name: undefined,
-        generated: { line: 3, column: 0 },
-        source: "inline",
-        original: { line: 1, column: 23 } },
-    ], "raw mappings were incorrectly generated");
-
-    chai.expect(generated.code).to.equal(
-      "function foo2() {\n  bar2;\n}",
-      "code was incorrectly generated"
+    const generated = generate(
+      ast,
+      {
+        filename: "inline",
+        sourceFileName: "inline",
+        sourceMaps: true,
+      },
+      code,
     );
+
+    chai.expect(generated.map).to.deep.equal(
+      {
+        version: 3,
+        sources: ["inline"],
+        names: ["foo", "bar"],
+        mappings: "AAAA,SAASA,IAAT,GAAe;AAAEC;AAAM",
+        sourcesContent: ["function foo() { bar; }\n"],
+      },
+      "sourcemap was incorrectly generated",
+    );
+
+    chai.expect(generated.rawMappings).to.deep.equal(
+      [
+        {
+          name: undefined,
+          generated: { line: 1, column: 0 },
+          source: "inline",
+          original: { line: 1, column: 0 },
+        },
+        {
+          name: "foo",
+          generated: { line: 1, column: 9 },
+          source: "inline",
+          original: { line: 1, column: 9 },
+        },
+        {
+          name: undefined,
+          generated: { line: 1, column: 13 },
+          source: "inline",
+          original: { line: 1, column: 0 },
+        },
+        {
+          name: undefined,
+          generated: { line: 1, column: 16 },
+          source: "inline",
+          original: { line: 1, column: 15 },
+        },
+        {
+          name: "bar",
+          generated: { line: 2, column: 0 },
+          source: "inline",
+          original: { line: 1, column: 17 },
+        },
+        {
+          name: undefined,
+          generated: { line: 3, column: 0 },
+          source: "inline",
+          original: { line: 1, column: 23 },
+        },
+      ],
+      "raw mappings were incorrectly generated",
+    );
+
+    chai
+      .expect(generated.code)
+      .to.equal(
+        "function foo2() {\n  bar2;\n}",
+        "code was incorrectly generated",
+      );
   });
 
   it("lazy source map generation", function() {
@@ -199,17 +262,22 @@ describe("generation", function () {
 
     chai.expect(generated.rawMappings).to.be.an("array");
 
-    chai.expect(generated).ownPropertyDescriptor("map").not.to.have.property("value");
+    chai
+      .expect(generated)
+      .ownPropertyDescriptor("map")
+      .not.to.have.property("value");
 
     chai.expect(generated.map).to.be.an("object");
   });
 });
 
-
 describe("programmatic generation", function() {
   it("numeric member expression", function() {
     // Should not generate `0.foo`
-    const mem = t.memberExpression(t.numericLiteral(60702), t.identifier("foo"));
+    const mem = t.memberExpression(
+      t.numericLiteral(60702),
+      t.identifier("foo"),
+    );
     new Function(generate(mem).code);
   });
 
@@ -220,10 +288,10 @@ describe("programmatic generation", function() {
         t.stringLiteral("while cond"),
         t.ifStatement(
           t.stringLiteral("nested"),
-          t.expressionStatement(t.numericLiteral(1))
-        )
+          t.expressionStatement(t.numericLiteral(1)),
+        ),
       ),
-      t.expressionStatement(t.stringLiteral("alt"))
+      t.expressionStatement(t.stringLiteral("alt")),
     );
 
     const ast = parse(generate(ifStatement).code);
@@ -233,35 +301,22 @@ describe("programmatic generation", function() {
   it("prints directives in block with empty body", function() {
     const blockStatement = t.blockStatement(
       [],
-      [t.directive(t.directiveLiteral("use strict"))]
+      [t.directive(t.directiveLiteral("use strict"))],
     );
 
     const output = generate(blockStatement).code;
-    assert.equal(output, [
-      "{",
-      "  \"use strict\";",
-      "}",
-    ].join("\n"));
+    assert.equal(output, ["{", '  "use strict";', "}"].join("\n"));
   });
 
   it("flow object indentation", function() {
     const objectStatement = t.objectTypeAnnotation(
-      [
-        t.objectTypeProperty(
-          t.identifier("bar"),
-          t.stringTypeAnnotation()
-        ),
-      ],
+      [t.objectTypeProperty(t.identifier("bar"), t.stringTypeAnnotation())],
+      null,
       null,
-      null
     );
 
     const output = generate(objectStatement).code;
-    assert.equal(output, [
-      "{",
-      "  bar: string,",
-      "}",
-    ].join("\n"));
+    assert.equal(output, ["{", "  bar: string,", "}"].join("\n"));
   });
 
   it("flow object indentation with empty leading ObjectTypeProperty", function() {
@@ -273,21 +328,17 @@ describe("programmatic generation", function() {
           t.anyTypeAnnotation(),
           t.identifier("Test"),
         ),
-      ]
+      ],
     );
 
     const output = generate(objectStatement).code;
 
-    assert.equal(output, [
-      "{",
-      "  [key: any]: Test,",
-      "}",
-    ].join("\n"));
+    assert.equal(output, ["{", "  [key: any]: Test,", "}"].join("\n"));
   });
 });
 
-describe("whitespace", function () {
-  it("empty token list", function () {
+describe("whitespace", function() {
+  it("empty token list", function() {
     const w = new Whitespace([]);
     assert.equal(w.getNewlinesBefore(t.stringLiteral("1")), 0);
   });
@@ -295,47 +346,55 @@ describe("whitespace", function () {
 
 const suites = fixtures(`${__dirname}/fixtures`);
 
-suites.forEach(function (testSuite) {
-  describe("generation/" + testSuite.title, function () {
-    testSuite.tests.forEach(function (task) {
-      it(task.title, !task.disabled && function () {
-        const expect = task.expect;
-        const actual = task.actual;
-        const actualCode = actual.code;
+suites.forEach(function(testSuite) {
+  describe("generation/" + testSuite.title, function() {
+    testSuite.tests.forEach(function(task) {
+      it(
+        task.title,
+        !task.disabled &&
+          function() {
+            const expect = task.expect;
+            const actual = task.actual;
+            const actualCode = actual.code;
 
-        if (actualCode) {
-          const actualAst = parse(actualCode, {
-            filename: actual.loc,
-            plugins: [
-              "asyncGenerators",
-              "classProperties",
-              "decorators",
-              "doExpressions",
-              "dynamicImport",
-              "exportExtensions",
-              "flow",
-              "functionBind",
-              "functionSent",
-              "jsx",
-              "objectRestSpread",
-              "optionalChaining",
-            ],
-            strictMode: false,
-            sourceType: "module",
-          });
-          const result = generate(actualAst, task.options, actualCode);
+            if (actualCode) {
+              const actualAst = parse(actualCode, {
+                filename: actual.loc,
+                plugins: [
+                  "asyncGenerators",
+                  "classProperties",
+                  "decorators",
+                  "doExpressions",
+                  "dynamicImport",
+                  "exportExtensions",
+                  "flow",
+                  "functionBind",
+                  "functionSent",
+                  "jsx",
+                  "objectRestSpread",
+                  "optionalChaining",
+                ],
+                strictMode: false,
+                sourceType: "module",
+              });
+              const result = generate(actualAst, task.options, actualCode);
 
-          if (
-            !expect.code && result.code && fs.statSync(path.dirname(expect.loc)).isDirectory() &&
-            !process.env.CI
-          ) {
-            console.log(`New test file created: ${expect.loc}`);
-            fs.writeFileSync(expect.loc, result.code);
-          } else {
-            chai.expect(result.code).to.be.equal(expect.code, actual.loc + " !== " + expect.loc);
-          }
-        }
-      });
+              if (
+                !expect.code &&
+                result.code &&
+                fs.statSync(path.dirname(expect.loc)).isDirectory() &&
+                !process.env.CI
+              ) {
+                console.log(`New test file created: ${expect.loc}`);
+                fs.writeFileSync(expect.loc, result.code);
+              } else {
+                chai
+                  .expect(result.code)
+                  .to.be.equal(expect.code, actual.loc + " !== " + expect.loc);
+              }
+            }
+          },
+      );
     });
   });
 });
diff --git a/packages/babel-helper-bindify-decorators/src/index.js b/packages/babel-helper-bindify-decorators/src/index.js
index debc145a4f..1d4379c3ab 100644
--- a/packages/babel-helper-bindify-decorators/src/index.js
+++ b/packages/babel-helper-bindify-decorators/src/index.js
@@ -1,7 +1,9 @@
 import type { NodePath } from "babel-traverse";
 import * as t from "babel-types";
 
-export default function bindifyDecorators(decorators: Array<NodePath>): Array<NodePath> {
+export default function bindifyDecorators(
+  decorators: Array<NodePath>,
+): Array<NodePath> {
   for (const decoratorPath of decorators) {
     const decorator = decoratorPath.node;
     const expression = decorator.expression;
@@ -19,13 +21,15 @@ export default function bindifyDecorators(decorators: Array<NodePath>): Array<No
       ref = expression.object;
     }
 
-    nodes.push(t.callExpression(
-      t.memberExpression(
-        t.memberExpression(ref, expression.property, expression.computed),
-        t.identifier("bind")
+    nodes.push(
+      t.callExpression(
+        t.memberExpression(
+          t.memberExpression(ref, expression.property, expression.computed),
+          t.identifier("bind"),
+        ),
+        [ref],
       ),
-      [ref]
-    ));
+    );
 
     if (nodes.length === 1) {
       decorator.expression = nodes[0];
diff --git a/packages/babel-helper-builder-binary-assignment-operator-visitor/src/index.js b/packages/babel-helper-builder-binary-assignment-operator-visitor/src/index.js
index 1b03a6681a..3ce441c71a 100644
--- a/packages/babel-helper-builder-binary-assignment-operator-visitor/src/index.js
+++ b/packages/babel-helper-builder-binary-assignment-operator-visitor/src/index.js
@@ -1,10 +1,7 @@
 import explode from "babel-helper-explode-assignable-expression";
 import * as t from "babel-types";
 
-export default function (opts: {
-  build: Function;
-  operator: string;
-}): Object {
+export default function(opts: { build: Function, operator: string }): Object {
   const visitor = {};
 
   function isAssignment(node) {
@@ -15,7 +12,7 @@ export default function (opts: {
     return t.assignmentExpression("=", left, right);
   }
 
-  visitor.ExpressionStatement = function (path, file) {
+  visitor.ExpressionStatement = function(path, file) {
     // hit the `AssignmentExpression` one below
     if (path.isCompletionRecord()) return;
 
@@ -25,24 +22,28 @@ export default function (opts: {
     const nodes = [];
     const exploded = explode(expr.left, nodes, file, path.scope, true);
 
-    nodes.push(t.expressionStatement(
-      buildAssignment(exploded.ref, opts.build(exploded.uid, expr.right))
-    ));
+    nodes.push(
+      t.expressionStatement(
+        buildAssignment(exploded.ref, opts.build(exploded.uid, expr.right)),
+      ),
+    );
 
     path.replaceWithMultiple(nodes);
   };
 
-  visitor.AssignmentExpression = function (path, file) {
+  visitor.AssignmentExpression = function(path, file) {
     const { node, scope } = path;
     if (!isAssignment(node)) return;
 
     const nodes = [];
     const exploded = explode(node.left, nodes, file, scope);
-    nodes.push(buildAssignment(exploded.ref, opts.build(exploded.uid, node.right)));
+    nodes.push(
+      buildAssignment(exploded.ref, opts.build(exploded.uid, node.right)),
+    );
     path.replaceWithMultiple(nodes);
   };
 
-  visitor.BinaryExpression = function (path) {
+  visitor.BinaryExpression = function(path) {
     const { node } = path;
     if (node.operator === opts.operator) {
       path.replaceWith(opts.build(node.left, node.right));
diff --git a/packages/babel-helper-builder-react-jsx/src/index.js b/packages/babel-helper-builder-react-jsx/src/index.js
index 370affcbca..01e8fe54c1 100644
--- a/packages/babel-helper-builder-react-jsx/src/index.js
+++ b/packages/babel-helper-builder-react-jsx/src/index.js
@@ -2,19 +2,21 @@ import esutils from "esutils";
 import * as t from "babel-types";
 
 type ElementState = {
-  tagExpr: Object; // tag node
-  tagName: string; // raw string tag name
-  args: Array<Object>; // array of call arguments
-  call?: Object; // optional call property that can be set to override the call expression returned
-  pre?: Function; // function called with (state: ElementState) before building attribs
-  post?: Function; // function called with (state: ElementState) after building attribs
+  tagExpr: Object, // tag node
+  tagName: string, // raw string tag name
+  args: Array<Object>, // array of call arguments
+  call?: Object, // optional call property that can be set to override the call expression returned
+  pre?: Function, // function called with (state: ElementState) before building attribs
+  post?: Function, // function called with (state: ElementState) after building attribs
 };
 
-export default function (opts) {
+export default function(opts) {
   const visitor = {};
 
-  visitor.JSXNamespacedName = function (path) {
-    throw path.buildCodeFrameError("Namespace tags are not supported. ReactJSX is not XML.");
+  visitor.JSXNamespacedName = function(path) {
+    throw path.buildCodeFrameError(
+      "Namespace tags are not supported. ReactJSX is not XML.",
+    );
   };
 
   visitor.JSXElement = {
@@ -45,7 +47,7 @@ export default function (opts) {
     } else if (t.isJSXMemberExpression(node)) {
       return t.memberExpression(
         convertJSXIdentifier(node.object, node),
-        convertJSXIdentifier(node.property, node)
+        convertJSXIdentifier(node.property, node),
       );
     }
 
@@ -127,7 +129,6 @@ export default function (opts) {
     return [];
   }
 
-
   /**
    * The logic for this is quite terse. It's because we need to
    * support spread elements. We loop over all attributes,
@@ -141,8 +142,10 @@ export default function (opts) {
 
     const useBuiltIns = file.opts.useBuiltIns || false;
     if (typeof useBuiltIns !== "boolean") {
-      throw new Error("transform-react-jsx currently only accepts a boolean option for " +
-        "useBuiltIns (defaults to false)");
+      throw new Error(
+        "transform-react-jsx currently only accepts a boolean option for " +
+          "useBuiltIns (defaults to false)",
+      );
     }
 
     while (attribs.length) {
@@ -166,9 +169,9 @@ export default function (opts) {
         objs.unshift(t.objectExpression([]));
       }
 
-      const helper = useBuiltIns ?
-        t.memberExpression(t.identifier("Object"), t.identifier("assign")) :
-        file.addHelper("extends");
+      const helper = useBuiltIns
+        ? t.memberExpression(t.identifier("Object"), t.identifier("assign"))
+        : file.addHelper("extends");
 
       // spread it
       attribs = t.callExpression(helper, objs);
diff --git a/packages/babel-helper-call-delegate/src/index.js b/packages/babel-helper-call-delegate/src/index.js
index fdf05257ce..8d9db20b75 100644
--- a/packages/babel-helper-call-delegate/src/index.js
+++ b/packages/babel-helper-call-delegate/src/index.js
@@ -18,15 +18,21 @@ const visitor = {
   },
 };
 
-export default function (path: NodePath, scope = path.scope) {
+export default function(path: NodePath, scope = path.scope) {
   const { node } = path;
-  const container = t.functionExpression(null, [], node.body, node.generator, node.async);
+  const container = t.functionExpression(
+    null,
+    [],
+    node.body,
+    node.generator,
+    node.async,
+  );
 
   let callee = container;
   let args = [];
 
   // todo: only hoist if necessary
-  hoistVariables(path, (id) => scope.push({ id }));
+  hoistVariables(path, id => scope.push({ id }));
 
   const state = {
     foundThis: false,
diff --git a/packages/babel-helper-define-map/src/index.js b/packages/babel-helper-define-map/src/index.js
index b0c45ab7e1..be06822f67 100644
--- a/packages/babel-helper-define-map/src/index.js
+++ b/packages/babel-helper-define-map/src/index.js
@@ -12,7 +12,13 @@ function toKind(node: Object) {
   return "value";
 }
 
-export function push(mutatorMap: Object, node: Object, kind: string, file, scope?): Object {
+export function push(
+  mutatorMap: Object,
+  node: Object,
+  kind: string,
+  file,
+  scope?,
+): Object {
   const alias = t.toKeyAlias(node);
 
   //
@@ -33,9 +39,11 @@ export function push(mutatorMap: Object, node: Object, kind: string, file, scope
   }
 
   if (node.decorators) {
-    const decorators = map.decorators = map.decorators || t.arrayExpression([]);
+    const decorators = (map.decorators =
+      map.decorators || t.arrayExpression([]));
     decorators.elements = decorators.elements.concat(
-      node.decorators.map((dec) => dec.expression).reverse());
+      node.decorators.map(dec => dec.expression).reverse(),
+    );
   }
 
   if (map.value || map.initializer) {
@@ -45,14 +53,24 @@ export function push(mutatorMap: Object, node: Object, kind: string, file, scope
   let key, value;
 
   // save the key so we can possibly do function name inferences
-  if (t.isObjectProperty(node) || t.isObjectMethod(node) || t.isClassMethod(node)) {
+  if (
+    t.isObjectProperty(node) ||
+    t.isObjectMethod(node) ||
+    t.isClassMethod(node)
+  ) {
     key = t.toComputedKey(node, node.key);
   }
 
   if (t.isObjectProperty(node) || t.isClassProperty(node)) {
     value = node.value;
   } else if (t.isObjectMethod(node) || t.isClassMethod(node)) {
-    value = t.functionExpression(null, node.params, node.body, node.generator, node.async);
+    value = t.functionExpression(
+      null,
+      node.params,
+      node.body,
+      node.generator,
+      node.async,
+    );
     value.returnType = node.returnType;
   }
 
@@ -62,8 +80,12 @@ export function push(mutatorMap: Object, node: Object, kind: string, file, scope
   }
 
   // infer function name
-  if (scope && t.isStringLiteral(key) && (kind === "value" || kind === "initializer") &&
-    t.isFunctionExpression(value)) {
+  if (
+    scope &&
+    t.isStringLiteral(key) &&
+    (kind === "value" || kind === "initializer") &&
+    t.isFunctionExpression(value)
+  ) {
     value = nameFunction({ id: key, node: value, scope });
   }
 
@@ -90,7 +112,9 @@ export function toComputedObjectFromClass(obj: Object): Object {
   for (let i = 0; i < obj.properties.length; i++) {
     const prop = obj.properties[i];
     const val = prop.value;
-    val.properties.unshift(t.objectProperty(t.identifier("key"), t.toComputedKey(prop)));
+    val.properties.unshift(
+      t.objectProperty(t.identifier("key"), t.toComputedKey(prop)),
+    );
     objExpr.elements.push(val);
   }
 
@@ -100,13 +124,13 @@ export function toComputedObjectFromClass(obj: Object): Object {
 export function toClassObject(mutatorMap: Object): Object {
   const objExpr = t.objectExpression([]);
 
-  Object.keys(mutatorMap).forEach(function (mutatorMapKey) {
+  Object.keys(mutatorMap).forEach(function(mutatorMapKey) {
     const map = mutatorMap[mutatorMapKey];
     const mapNode = t.objectExpression([]);
 
     const propNode = t.objectProperty(map._key, mapNode, map._computed);
 
-    Object.keys(map).forEach(function (key) {
+    Object.keys(map).forEach(function(key) {
       let node = map[key];
       if (key[0] === "_") return;
 
@@ -127,7 +151,7 @@ export function toClassObject(mutatorMap: Object): Object {
 }
 
 export function toDefineObject(mutatorMap: Object): Object {
-  Object.keys(mutatorMap).forEach(function (key) {
+  Object.keys(mutatorMap).forEach(function(key) {
     const map = mutatorMap[key];
     if (map.value) map.writable = t.booleanLiteral(true);
     map.configurable = t.booleanLiteral(true);
diff --git a/packages/babel-helper-explode-assignable-expression/src/index.js b/packages/babel-helper-explode-assignable-expression/src/index.js
index 60f4940bb8..e7aa7d94e0 100644
--- a/packages/babel-helper-explode-assignable-expression/src/index.js
+++ b/packages/babel-helper-explode-assignable-expression/src/index.js
@@ -20,7 +20,7 @@ function getObjRef(node, nodes, file, scope) {
   } else if (t.isMemberExpression(node)) {
     ref = node.object;
 
-    if (t.isSuper(ref) || t.isIdentifier(ref) && scope.hasBinding(ref.name)) {
+    if (t.isSuper(ref) || (t.isIdentifier(ref) && scope.hasBinding(ref.name))) {
       // the object reference that we need to save is locally declared
       // so as per the previous comment we can be 100% sure evaluating
       // it multiple times will be safe
@@ -32,9 +32,7 @@ function getObjRef(node, nodes, file, scope) {
   }
 
   const temp = scope.generateUidIdentifierBasedOnNode(ref);
-  nodes.push(t.variableDeclaration("var", [
-    t.variableDeclarator(temp, ref),
-  ]));
+  nodes.push(t.variableDeclaration("var", [t.variableDeclarator(temp, ref)]));
   return temp;
 }
 
@@ -44,21 +42,19 @@ function getPropRef(node, nodes, file, scope) {
   if (t.isLiteral(key) && t.isPureish(key)) return key;
 
   const temp = scope.generateUidIdentifierBasedOnNode(prop);
-  nodes.push(t.variableDeclaration("var", [
-    t.variableDeclarator(temp, prop),
-  ]));
+  nodes.push(t.variableDeclaration("var", [t.variableDeclarator(temp, prop)]));
   return temp;
 }
 
-export default function (
+export default function(
   node: Object,
   nodes: Array<Object>,
   file,
   scope: Scope,
   allowedSingleIdent?: boolean,
 ): {
-  uid: Object;
-  ref: Object;
+  uid: Object,
+  ref: Object,
 } {
   let obj;
   if (t.isIdentifier(node) && allowedSingleIdent) {
diff --git a/packages/babel-helper-explode-class/src/index.js b/packages/babel-helper-explode-class/src/index.js
index 2ced5be5b1..1fd2de8c92 100644
--- a/packages/babel-helper-explode-class/src/index.js
+++ b/packages/babel-helper-explode-class/src/index.js
@@ -2,7 +2,7 @@ import bindifyDecorators from "babel-helper-bindify-decorators";
 import type { NodePath } from "babel-traverse";
 import * as t from "babel-types";
 
-export default function (classPath) {
+export default function(classPath) {
   classPath.assertClass();
 
   const memoisedExpressions = [];
@@ -44,6 +44,8 @@ export default function (classPath) {
   }
 
   if (memoisedExpressions) {
-    classPath.insertBefore(memoisedExpressions.map((expr) => t.expressionStatement(expr)));
+    classPath.insertBefore(
+      memoisedExpressions.map(expr => t.expressionStatement(expr)),
+    );
   }
 }
diff --git a/packages/babel-helper-fixtures/src/index.js b/packages/babel-helper-fixtures/src/index.js
index 96adcabab0..2c82fda796 100644
--- a/packages/babel-helper-fixtures/src/index.js
+++ b/packages/babel-helper-fixtures/src/index.js
@@ -15,25 +15,25 @@ function humanize(val, noext) {
 }
 
 type TestFile = {
-  loc: string;
-  code: string;
-  filename: string;
+  loc: string,
+  code: string,
+  filename: string,
 };
 
 type Test = {
-  title: string;
-  disabled: boolean;
-  options: Object;
-  exec: TestFile;
-  actual: TestFile;
-  expected: TestFile;
+  title: string,
+  disabled: boolean,
+  options: Object,
+  exec: TestFile,
+  actual: TestFile,
+  expected: TestFile,
 };
 
 type Suite = {
-  options: Object;
-  tests: Array<Test>;
-  title: string;
-  filename: string;
+  options: Object,
+  tests: Array<Test>,
+  title: string,
+  filename: string,
 };
 
 function assertDirectory(loc) {
@@ -50,7 +50,9 @@ function shouldIgnore(name, blacklist?: Array<string>) {
   const ext = path.extname(name);
   const base = path.basename(name, ext);
 
-  return name[0] === "." || ext === ".md" || base === "LICENSE" || base === "options";
+  return (
+    name[0] === "." || ext === ".md" || base === "LICENSE" || base === "options"
+  );
 }
 
 export default function get(entryLoc): Array<Suite> {
@@ -133,7 +135,9 @@ export default function get(entryLoc): Array<Suite> {
         const minimumVersion = semver.clean(taskOpts.minNodeVersion);
 
         if (minimumVersion == null) {
-          throw new Error(`'minNodeVersion' has invalid semver format: ${taskOpts.minNodeVersion}`);
+          throw new Error(
+            `'minNodeVersion' has invalid semver format: ${taskOpts.minNodeVersion}`,
+          );
         }
 
         if (semver.lt(nodeVersion, minimumVersion)) {
diff --git a/packages/babel-helper-function-name/src/index.js b/packages/babel-helper-function-name/src/index.js
index 9783c6fc1a..e0420de933 100644
--- a/packages/babel-helper-function-name/src/index.js
+++ b/packages/babel-helper-function-name/src/index.js
@@ -56,7 +56,9 @@ function wrap(state, method, id, scope) {
 
       // need to add a wrapper since we can't change the references
       let build = buildPropertyMethodAssignmentWrapper;
-      if (method.generator) build = buildGeneratorPropertyMethodAssignmentWrapper;
+      if (method.generator) {
+        build = buildGeneratorPropertyMethodAssignmentWrapper;
+      }
       const template = build({
         FUNCTION: method,
         FUNCTION_ID: id,
@@ -125,12 +127,15 @@ function visit(node, name, scope) {
   return state;
 }
 
-export default function ({ node, parent, scope, id }) {
+export default function({ node, parent, scope, id }) {
   // has an `id` so we don't need to infer one
   if (node.id) return;
 
-  if ((t.isObjectProperty(parent) || t.isObjectMethod(parent, { kind: "method" })) &&
-    (!parent.computed || t.isLiteral(parent.key))) {
+  if (
+    (t.isObjectProperty(parent) ||
+      t.isObjectMethod(parent, { kind: "method" })) &&
+    (!parent.computed || t.isLiteral(parent.key))
+  ) {
     // { foo() {} };
     id = parent.key;
   } else if (t.isVariableDeclarator(parent)) {
@@ -139,7 +144,11 @@ export default function ({ node, parent, scope, id }) {
 
     if (t.isIdentifier(id)) {
       const binding = scope.parent.getBinding(id.name);
-      if (binding && binding.constant && scope.getBinding(id.name) === binding) {
+      if (
+        binding &&
+        binding.constant &&
+        scope.getBinding(id.name) === binding
+      ) {
         // always going to reference this method
         node.id = id;
         node.id[t.NOT_LOCAL_BINDING] = true;
diff --git a/packages/babel-helper-get-function-arity/src/index.js b/packages/babel-helper-get-function-arity/src/index.js
index c54613f6fe..0c3f5f1977 100644
--- a/packages/babel-helper-get-function-arity/src/index.js
+++ b/packages/babel-helper-get-function-arity/src/index.js
@@ -1,6 +1,6 @@
 import * as t from "babel-types";
 
-export default function (node): number {
+export default function(node): number {
   const params: Array<Object> = node.params;
   for (let i = 0; i < params.length; i++) {
     const param = params[i];
diff --git a/packages/babel-helper-hoist-variables/src/index.js b/packages/babel-helper-hoist-variables/src/index.js
index ca5e640600..d09c864814 100644
--- a/packages/babel-helper-hoist-variables/src/index.js
+++ b/packages/babel-helper-hoist-variables/src/index.js
@@ -21,9 +21,11 @@ const visitor = {
       firstId = declar.node.id;
 
       if (declar.node.init) {
-        nodes.push(t.expressionStatement(
-          t.assignmentExpression("=", declar.node.id, declar.node.init)
-        ));
+        nodes.push(
+          t.expressionStatement(
+            t.assignmentExpression("=", declar.node.id, declar.node.init),
+          ),
+        );
       }
 
       for (const name in declar.getBindingIdentifiers()) {
@@ -40,6 +42,6 @@ const visitor = {
   },
 };
 
-export default function (path, emit: Function, kind: "var" | "let" = "var") {
+export default function(path, emit: Function, kind: "var" | "let" = "var") {
   path.traverse(visitor, { kind, emit });
 }
diff --git a/packages/babel-helper-optimise-call-expression/src/index.js b/packages/babel-helper-optimise-call-expression/src/index.js
index 485f986321..b8613709e9 100644
--- a/packages/babel-helper-optimise-call-expression/src/index.js
+++ b/packages/babel-helper-optimise-call-expression/src/index.js
@@ -1,17 +1,20 @@
 import * as t from "babel-types";
 
-export default function (callee, thisNode, args) {
-  if (args.length === 1 && t.isSpreadElement(args[0]) &&
-    t.isIdentifier(args[0].argument, { name: "arguments" })) {
+export default function(callee, thisNode, args) {
+  if (
+    args.length === 1 &&
+    t.isSpreadElement(args[0]) &&
+    t.isIdentifier(args[0].argument, { name: "arguments" })
+  ) {
     // eg. super(...arguments);
-    return t.callExpression(
-      t.memberExpression(callee, t.identifier("apply")),
-      [thisNode, args[0].argument]
-    );
+    return t.callExpression(t.memberExpression(callee, t.identifier("apply")), [
+      thisNode,
+      args[0].argument,
+    ]);
   } else {
-    return t.callExpression(
-      t.memberExpression(callee, t.identifier("call")),
-      [thisNode, ...args]
-    );
+    return t.callExpression(t.memberExpression(callee, t.identifier("call")), [
+      thisNode,
+      ...args,
+    ]);
   }
 }
diff --git a/packages/babel-helper-plugin-test-runner/src/index.js b/packages/babel-helper-plugin-test-runner/src/index.js
index 37bcc4360c..7877c5d7f5 100644
--- a/packages/babel-helper-plugin-test-runner/src/index.js
+++ b/packages/babel-helper-plugin-test-runner/src/index.js
@@ -1,7 +1,7 @@
 import testRunner from "babel-helper-transform-fixture-test-runner";
 import path from "path";
 
-export default function (loc) {
+export default function(loc) {
   const name = path.basename(path.dirname(loc));
   testRunner(loc + "/fixtures", name);
 }
diff --git a/packages/babel-helper-remap-async-to-generator/src/for-await.js b/packages/babel-helper-remap-async-to-generator/src/for-await.js
index c9b638283b..359eac3f6c 100644
--- a/packages/babel-helper-remap-async-to-generator/src/for-await.js
+++ b/packages/babel-helper-remap-async-to-generator/src/for-await.js
@@ -48,13 +48,17 @@ const forAwaitVisitor = {
     const callee = path.node.callee;
 
     // if no await wrapping is being applied, unwrap the call expression
-    if (t.isIdentifier(callee) && callee.name === "AWAIT" && !replacements.AWAIT) {
+    if (
+      t.isIdentifier(callee) &&
+      callee.name === "AWAIT" &&
+      !replacements.AWAIT
+    ) {
       path.replaceWith(path.node.arguments[0]);
     }
   },
 };
 
-export default function (path, helpers) {
+export default function(path, helpers) {
   const { node, scope, parent } = path;
 
   const stepKey = scope.generateUidIdentifier("step");
@@ -64,7 +68,9 @@ export default function (path, helpers) {
 
   if (t.isIdentifier(left) || t.isPattern(left) || t.isMemberExpression(left)) {
     // for await (i of test), for await ({ i } of test)
-    declar = t.expressionStatement(t.assignmentExpression("=", left, stepValue));
+    declar = t.expressionStatement(
+      t.assignmentExpression("=", left, stepValue),
+    );
   } else if (t.isVariableDeclaration(left)) {
     // for await (let i of test)
     declar = t.variableDeclaration(left.kind, [
@@ -76,7 +82,9 @@ export default function (path, helpers) {
 
   traverse(template, forAwaitVisitor, null, {
     ITERATOR_HAD_ERROR_KEY: scope.generateUidIdentifier("didIteratorError"),
-    ITERATOR_COMPLETION: scope.generateUidIdentifier("iteratorNormalCompletion"),
+    ITERATOR_COMPLETION: scope.generateUidIdentifier(
+      "iteratorNormalCompletion",
+    ),
     ITERATOR_ERROR_KEY: scope.generateUidIdentifier("iteratorError"),
     ITERATOR_KEY: scope.generateUidIdentifier("iterator"),
     GET_ITERATOR: helpers.getAsyncIterator,
diff --git a/packages/babel-helper-remap-async-to-generator/src/index.js b/packages/babel-helper-remap-async-to-generator/src/index.js
index 04097c7f8e..f4aea8de6c 100644
--- a/packages/babel-helper-remap-async-to-generator/src/index.js
+++ b/packages/babel-helper-remap-async-to-generator/src/index.js
@@ -70,7 +70,6 @@ const awaitVisitor = {
       path.replaceWithMultiple(build.node);
     }
   },
-
 };
 
 function classOrObjectMethod(path: NodePath, callId: Object) {
@@ -79,12 +78,16 @@ function classOrObjectMethod(path: NodePath, callId: Object) {
 
   node.async = false;
 
-  const container = t.functionExpression(null, [], t.blockStatement(body.body), true);
+  const container = t.functionExpression(
+    null,
+    [],
+    t.blockStatement(body.body),
+    true,
+  );
   body.body = [
-    t.returnStatement(t.callExpression(
-      t.callExpression(callId, [container]),
-      []
-    )),
+    t.returnStatement(
+      t.callExpression(t.callExpression(callId, [container]), []),
+    ),
   ];
 
   // Regardless of whether or not the wrapped function is a an async method
@@ -92,7 +95,9 @@ function classOrObjectMethod(path: NodePath, callId: Object) {
   node.generator = false;
 
   // Unwrap the wrapper IIFE's environment so super and this and such still work.
-  path.get("body.body.0.argument.callee.arguments.0").unwrapFunctionEnvironment();
+  path
+    .get("body.body.0.argument.callee.arguments.0")
+    .unwrapFunctionEnvironment();
 }
 
 function plainFunction(path: NodePath, callId: Object) {
@@ -121,25 +126,29 @@ function plainFunction(path: NodePath, callId: Object) {
     NAME: asyncFnId || null,
     REF: path.scope.generateUidIdentifier("ref"),
     FUNCTION: built,
-    PARAMS: node.params.reduce((acc, param) => {
-      acc.done = acc.done || t.isAssignmentPattern(param) || t.isRestElement(param);
+    PARAMS: node.params.reduce(
+      (acc, param) => {
+        acc.done =
+          acc.done || t.isAssignmentPattern(param) || t.isRestElement(param);
 
-      if (!acc.done) {
-        acc.params.push(path.scope.generateUidIdentifier("x"));
-      }
+        if (!acc.done) {
+          acc.params.push(path.scope.generateUidIdentifier("x"));
+        }
 
-      return acc;
-    }, {
-      params: [],
-      done: false,
-    }).params,
+        return acc;
+      },
+      {
+        params: [],
+        done: false,
+      },
+    ).params,
   }).expression;
 
   if (isDeclaration) {
     const declar = t.variableDeclaration("let", [
       t.variableDeclarator(
         t.identifier(asyncFnId.name),
-        t.callExpression(container, [])
+        t.callExpression(container, []),
       ),
     ]);
     declar._blockHoist = true;
@@ -149,14 +158,12 @@ function plainFunction(path: NodePath, callId: Object) {
       // the identifier into an expressionStatement
       path.parentPath.insertBefore(declar);
       path.parentPath.replaceWith(
-        t.exportNamedDeclaration(null,
-          [
-            t.exportSpecifier(
-              t.identifier(asyncFnId.name),
-              t.identifier("default")
-            ),
-          ]
-        )
+        t.exportNamedDeclaration(null, [
+          t.exportSpecifier(
+            t.identifier(asyncFnId.name),
+            t.identifier("default"),
+          ),
+        ]),
       );
       return;
     }
@@ -182,7 +189,7 @@ function plainFunction(path: NodePath, callId: Object) {
   }
 }
 
-export default function (path: NodePath, file: Object, helpers: Object) {
+export default function(path: NodePath, file: Object, helpers: Object) {
   if (!helpers) {
     // bc for 6.15 and earlier
     helpers = { wrapAsync: file };
diff --git a/packages/babel-helper-replace-supers/src/index.js b/packages/babel-helper-replace-supers/src/index.js
index bc17d07390..26ffe4d75a 100644
--- a/packages/babel-helper-replace-supers/src/index.js
+++ b/packages/babel-helper-replace-supers/src/index.js
@@ -30,16 +30,19 @@ function isMemberExpressionSuper(node) {
  *   CLASS.prototype.__proto__ || Object.getPrototypeOf(CLASS.prototype)
  */
 function getPrototypeOfExpression(objectRef, isStatic) {
-  const targetRef = isStatic ? objectRef : t.memberExpression(objectRef, t.identifier("prototype"));
+  const targetRef = isStatic
+    ? objectRef
+    : t.memberExpression(objectRef, t.identifier("prototype"));
 
   return t.logicalExpression(
     "||",
     t.memberExpression(targetRef, t.identifier("__proto__")),
     t.callExpression(
-      t.memberExpression(t.identifier("Object"), t.identifier("getPrototypeOf")),
-      [
-        targetRef,
-      ]
+      t.memberExpression(
+        t.identifier("Object"),
+        t.identifier("getPrototypeOf"),
+      ),
+      [targetRef],
     ),
   );
 }
@@ -119,14 +122,14 @@ export default class ReplaceSupers {
   scope: Scope;
   file;
   opts: {
-    forceSuperMemoisation: boolean;
-    getObjetRef: Function;
-    methodPath: NodePath;
-    methodNode: Object;
-    superRef: Object;
-    isStatic: boolean;
-    isLoose: boolean;
-    file: any;
+    forceSuperMemoisation: boolean,
+    getObjetRef: Function,
+    methodPath: NodePath,
+    methodNode: Object,
+    superRef: Object,
+    isStatic: boolean,
+    isLoose: boolean,
+    file: any,
   };
 
   getObjectRef() {
@@ -143,16 +146,17 @@ export default class ReplaceSupers {
    *
    */
 
-  setSuperProperty(property: Object, value: Object, isComputed: boolean): Object {
-    return t.callExpression(
-      this.file.addHelper("set"),
-      [
-        getPrototypeOfExpression(this.getObjectRef(), this.isStatic),
-        isComputed ? property : t.stringLiteral(property.name),
-        value,
-        t.thisExpression(),
-      ]
-    );
+  setSuperProperty(
+    property: Object,
+    value: Object,
+    isComputed: boolean,
+  ): Object {
+    return t.callExpression(this.file.addHelper("set"), [
+      getPrototypeOfExpression(this.getObjectRef(), this.isStatic),
+      isComputed ? property : t.stringLiteral(property.name),
+      value,
+      t.thisExpression(),
+    ]);
   }
 
   /**
@@ -165,14 +169,11 @@ export default class ReplaceSupers {
    */
 
   getSuperProperty(property: Object, isComputed: boolean): Object {
-    return t.callExpression(
-      this.file.addHelper("get"),
-      [
-        getPrototypeOfExpression(this.getObjectRef(), this.isStatic),
-        isComputed ? property : t.stringLiteral(property.name),
-        t.thisExpression(),
-      ]
-    );
+    return t.callExpression(this.file.addHelper("get"), [
+      getPrototypeOfExpression(this.getObjectRef(), this.isStatic),
+      isComputed ? property : t.stringLiteral(property.name),
+      t.thisExpression(),
+    ]);
   }
 
   replace() {
@@ -214,16 +215,23 @@ export default class ReplaceSupers {
   specHandleAssignmentExpression(ref, path, node) {
     if (node.operator === "=") {
       // super.name = "val"; -> _set(Object.getPrototypeOf(objectRef.prototype), "name", this);
-      return this.setSuperProperty(node.left.property, node.right, node.left.computed);
+      return this.setSuperProperty(
+        node.left.property,
+        node.right,
+        node.left.computed,
+      );
     } else {
       // super.age += 2; -> let _ref = super.age; super.age = _ref + 2;
       ref = ref || path.scope.generateUidIdentifier("ref");
       return [
-        t.variableDeclaration("var", [
-          t.variableDeclarator(ref, node.left),
-        ]),
-        t.expressionStatement(t.assignmentExpression("=", node.left,
-          t.binaryExpression(node.operator.slice(0, -1), ref, node.right))),
+        t.variableDeclaration("var", [t.variableDeclarator(ref, node.left)]),
+        t.expressionStatement(
+          t.assignmentExpression(
+            "=",
+            node.left,
+            t.binaryExpression(node.operator.slice(0, -1), ref, node.right),
+          ),
+        ),
       ];
     }
   }
@@ -258,8 +266,15 @@ export default class ReplaceSupers {
       // _get(Object.getPrototypeOf(objectRef.prototype), "name", this);
       property = node.property;
       computed = node.computed;
-    } else if (t.isUpdateExpression(node) && isMemberExpressionSuper(node.argument)) {
-      const binary = t.assignmentExpression(node.operator[0] + "=", node.argument, t.numericLiteral(1));
+    } else if (
+      t.isUpdateExpression(node) &&
+      isMemberExpressionSuper(node.argument)
+    ) {
+      const binary = t.assignmentExpression(
+        node.operator[0] + "=",
+        node.argument,
+        t.numericLiteral(1),
+      );
       if (node.prefix) {
         // ++super.foo;
         // to
@@ -270,9 +285,14 @@ export default class ReplaceSupers {
         // to
         // let _ref = super.foo; super.foo = _ref + 1;
         const ref = path.scope.generateUidIdentifier("ref");
-        return this.specHandleAssignmentExpression(ref, path, binary).concat(t.expressionStatement(ref));
+        return this.specHandleAssignmentExpression(ref, path, binary).concat(
+          t.expressionStatement(ref),
+        );
       }
-    } else if (t.isAssignmentExpression(node) && isMemberExpressionSuper(node.left)) {
+    } else if (
+      t.isAssignmentExpression(node) &&
+      isMemberExpressionSuper(node.left)
+    ) {
       return this.specHandleAssignmentExpression(null, path, node);
     }
 
diff --git a/packages/babel-helper-transform-fixture-test-runner/src/helpers.js b/packages/babel-helper-transform-fixture-test-runner/src/helpers.js
index f289042638..fcf825cbfd 100644
--- a/packages/babel-helper-transform-fixture-test-runner/src/helpers.js
+++ b/packages/babel-helper-transform-fixture-test-runner/src/helpers.js
@@ -4,13 +4,9 @@ export function assertNoOwnProperties(obj) {
   assert.equal(Object.getOwnPropertyNames(obj).length, 0);
 }
 
-export function assertHasOwnProperty() {
+export function assertHasOwnProperty() {}
 
-}
-
-export function assertLacksOwnProperty() {
-
-}
+export function assertLacksOwnProperty() {}
 
 export function multiline(arr) {
   return arr.join("\n");
diff --git a/packages/babel-helper-transform-fixture-test-runner/src/index.js b/packages/babel-helper-transform-fixture-test-runner/src/index.js
index 6b62ea5e40..ffb1af2774 100644
--- a/packages/babel-helper-transform-fixture-test-runner/src/index.js
+++ b/packages/babel-helper-transform-fixture-test-runner/src/index.js
@@ -38,7 +38,9 @@ runCodeInTestContext(buildExternalHelpers());
  * This allows us to run our unittests
  */
 function runModuleInTestContext(id: string, relativeFilename: string) {
-  const filename = resolve.sync(id, { basedir: path.dirname(relativeFilename) });
+  const filename = resolve.sync(id, {
+    basedir: path.dirname(relativeFilename),
+  });
 
   // Expose Node-internal modules if the tests want them. Note, this will not execute inside
   // the context's global scope.
@@ -46,20 +48,22 @@ function runModuleInTestContext(id: string, relativeFilename: string) {
 
   if (moduleCache[filename]) return moduleCache[filename].exports;
 
-  const module = moduleCache[filename] = {
+  const module = (moduleCache[filename] = {
     id: filename,
     exports: {},
-  };
+  });
   const dirname = path.dirname(filename);
-  const req = (id) => runModuleInTestContext(id, filename);
+  const req = id => runModuleInTestContext(id, filename);
 
   const src = fs.readFileSync(filename, "utf8");
   const code = `(function (exports, require, module, __filename, __dirname) {${src}\n});`;
 
-  vm.runInContext(code, testContext, {
-    filename,
-    displayErrors: true,
-  }).call(module.exports, module.exports, req, module, filename, dirname);
+  vm
+    .runInContext(code, testContext, {
+      filename,
+      displayErrors: true,
+    })
+    .call(module.exports, module.exports, req, module, filename, dirname);
 
   return module.exports;
 }
@@ -69,10 +73,13 @@ function runModuleInTestContext(id: string, relativeFilename: string) {
  *
  * Exposed for unit tests, not for use as an API.
  */
-export function runCodeInTestContext(code: string, opts: {filename?: string} = {}) {
+export function runCodeInTestContext(
+  code: string,
+  opts: { filename?: string } = {},
+) {
   const filename = opts.filename || null;
   const dirname = filename ? path.dirname(filename) : null;
-  const req = filename ? ((id) => runModuleInTestContext(id, filename)) : null;
+  const req = filename ? id => runModuleInTestContext(id, filename) : null;
 
   const module = {
     id: filename,
@@ -90,21 +97,21 @@ export function runCodeInTestContext(code: string, opts: {filename?: string} = {
 }
 
 function wrapPackagesArray(type, names, optionsDir) {
-  return (names || []).map(function (val) {
+  return (names || []).map(function(val) {
     if (typeof val === "string") val = [val];
 
     // relative path (outside of monorepo)
     if (val[0][0] === ".") {
-
       if (!optionsDir) {
-        throw new Error("Please provide an options.json in test dir when using a " +
-          "relative plugin path.");
+        throw new Error(
+          "Please provide an options.json in test dir when using a " +
+            "relative plugin path.",
+        );
       }
 
       val[0] = path.resolve(optionsDir, val[0]);
-    }
-    // check node_modules/babel-x-y
-    else {
+    } else {
+      // check node_modules/babel-x-y
       val[0] = __dirname + "/../../babel-" + type + "-" + val[0];
     }
 
@@ -120,15 +127,25 @@ function run(task) {
   const optionsDir = task.optionsDir;
 
   function getOpts(self) {
-    const newOpts = merge({
-      filename: self.loc,
-    }, opts);
+    const newOpts = merge(
+      {
+        filename: self.loc,
+      },
+      opts,
+    );
 
     newOpts.plugins = wrapPackagesArray("plugin", newOpts.plugins, optionsDir);
-    newOpts.presets = wrapPackagesArray("preset", newOpts.presets, optionsDir).map(function (val) {
+    newOpts.presets = wrapPackagesArray(
+      "preset",
+      newOpts.presets,
+      optionsDir,
+    ).map(function(val) {
       if (val.length > 2) {
-        throw new Error("Unexpected extra options " + JSON.stringify(val.slice(2)) +
-          " passed to preset.");
+        throw new Error(
+          "Unexpected extra options " +
+            JSON.stringify(val.slice(2)) +
+            " passed to preset.",
+        );
       }
 
       return val;
@@ -160,14 +177,19 @@ function run(task) {
   if (!execCode || actualCode) {
     result = babel.transform(actualCode, getOpts(actual));
     if (
-      !expect.code && result.code && !opts.throws && fs.statSync(path.dirname(expect.loc)).isDirectory() &&
+      !expect.code &&
+      result.code &&
+      !opts.throws &&
+      fs.statSync(path.dirname(expect.loc)).isDirectory() &&
       !process.env.CI
     ) {
       console.log(`New test file created: ${expect.loc}`);
       fs.writeFileSync(expect.loc, result.code);
     } else {
       actualCode = result.code.trim();
-      chai.expect(actualCode).to.be.equal(expectCode, actual.loc + " !== " + expect.loc);
+      chai
+        .expect(actualCode)
+        .to.be.equal(expectCode, actual.loc + " !== " + expect.loc);
     }
   }
 
@@ -178,11 +200,13 @@ function run(task) {
   if (task.sourceMappings) {
     const consumer = new sourceMap.SourceMapConsumer(result.map);
 
-    task.sourceMappings.forEach(function (mapping) {
+    task.sourceMappings.forEach(function(mapping) {
       const actual = mapping.original;
 
       const expect = consumer.originalPositionFor(mapping.generated);
-      chai.expect({ line: expect.line, column: expect.column }).to.deep.equal(actual);
+      chai
+        .expect({ line: expect.line, column: expect.column })
+        .to.deep.equal(actual);
     });
   }
 
@@ -191,7 +215,7 @@ function run(task) {
   }
 }
 
-export default function (
+export default function(
   fixturesLoc: string,
   name: string,
   suiteOpts = {},
@@ -203,49 +227,59 @@ export default function (
   for (const testSuite of suites) {
     if (includes(suiteOpts.ignoreSuites, testSuite.title)) continue;
 
-    describe(name + "/" + testSuite.title, function () {
+    describe(name + "/" + testSuite.title, function() {
       for (const task of testSuite.tests) {
-        if (includes(suiteOpts.ignoreTasks, task.title) ||
-            includes(suiteOpts.ignoreTasks, testSuite.title + "/" + task.title)) continue;
+        if (
+          includes(suiteOpts.ignoreTasks, task.title) ||
+          includes(suiteOpts.ignoreTasks, testSuite.title + "/" + task.title)
+        ) {
+          continue;
+        }
 
-        it(task.title, !task.disabled && function () {
-          function runTask() {
-            run(task);
-          }
-
-          defaults(task.options, {
-            filenameRelative: task.expect.filename,
-            sourceFileName: task.actual.filename,
-            sourceMapTarget: task.expect.filename,
-            suppressDeprecationMessages: true,
-            babelrc: false,
-            sourceMap: !!(task.sourceMappings || task.sourceMap),
-          });
-
-          extend(task.options, taskOpts);
-
-          if (dynamicOpts) dynamicOpts(task.options, task);
-
-          const throwMsg = task.options.throws;
-          if (throwMsg) {
-            // internal api doesn't have this option but it's best not to pollute
-            // the options object with useless options
-            delete task.options.throws;
-
-            assert.throws(runTask, function (err) {
-              return throwMsg === true || err.message.indexOf(throwMsg) >= 0;
-            });
-          } else {
-            if (task.exec.code) {
-              const result = run(task);
-              if (result && typeof result.then === "function") {
-                return result;
+        it(
+          task.title,
+          !task.disabled &&
+            function() {
+              function runTask() {
+                run(task);
               }
-            } else {
-              runTask();
-            }
-          }
-        });
+
+              defaults(task.options, {
+                filenameRelative: task.expect.filename,
+                sourceFileName: task.actual.filename,
+                sourceMapTarget: task.expect.filename,
+                suppressDeprecationMessages: true,
+                babelrc: false,
+                sourceMap: !!(task.sourceMappings || task.sourceMap),
+              });
+
+              extend(task.options, taskOpts);
+
+              if (dynamicOpts) dynamicOpts(task.options, task);
+
+              const throwMsg = task.options.throws;
+              if (throwMsg) {
+                // internal api doesn't have this option but it's best not to pollute
+                // the options object with useless options
+                delete task.options.throws;
+
+                assert.throws(runTask, function(err) {
+                  return (
+                    throwMsg === true || err.message.indexOf(throwMsg) >= 0
+                  );
+                });
+              } else {
+                if (task.exec.code) {
+                  const result = run(task);
+                  if (result && typeof result.then === "function") {
+                    return result;
+                  }
+                } else {
+                  runTask();
+                }
+              }
+            },
+        );
       }
     });
   }
diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 705d607f45..0df0ef3fa1 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -359,7 +359,6 @@ helpers.get = template(`
   });
 `);
 
-
 helpers.inherits = template(`
   (function (subClass, superClass) {
     if (typeof superClass !== "function" && superClass !== null) {
@@ -395,7 +394,6 @@ helpers.instanceof = template(`
   });
 `);
 
-
 helpers.interopRequireDefault = template(`
   (function (obj) {
     return obj && obj.__esModule ? obj : { default: obj };
diff --git a/packages/babel-helpers/src/index.js b/packages/babel-helpers/src/index.js
index c25dce9c14..58dc5e85aa 100644
--- a/packages/babel-helpers/src/index.js
+++ b/packages/babel-helpers/src/index.js
@@ -8,7 +8,7 @@ export function get(name) {
 }
 
 export const list = Object.keys(helpers)
-  .map((name) => name.replace(/^_/, ""))
-  .filter((name) => name !== "__esModule");
+  .map(name => name.replace(/^_/, ""))
+  .filter(name => name !== "__esModule");
 
 export default get;
diff --git a/packages/babel-messages/src/index.js b/packages/babel-messages/src/index.js
index 088e586b09..5870dc6d8e 100644
--- a/packages/babel-messages/src/index.js
+++ b/packages/babel-messages/src/index.js
@@ -8,38 +8,55 @@ import * as util from "util";
  */
 
 export const MESSAGES = {
-  tailCallReassignmentDeopt: "Function reference has been reassigned, so it will probably be dereferenced, therefore we can't optimise this with confidence",
+  tailCallReassignmentDeopt:
+    "Function reference has been reassigned, so it will probably be dereferenced, therefore we can't optimise this with confidence",
   classesIllegalBareSuper: "Illegal use of bare super",
-  classesIllegalSuperCall: "Direct super call is illegal in non-constructor, use super.$1() instead",
+  classesIllegalSuperCall:
+    "Direct super call is illegal in non-constructor, use super.$1() instead",
   scopeDuplicateDeclaration: "Duplicate declaration $1",
   settersNoRest: "Setters aren't allowed to have a rest",
   noAssignmentsInForHead: "No assignments allowed in for-in/of head",
-  expectedMemberExpressionOrIdentifier: "Expected type MemberExpression or Identifier",
-  invalidParentForThisNode: "We don't know how to handle this node within the current parent - please open an issue",
+  expectedMemberExpressionOrIdentifier:
+    "Expected type MemberExpression or Identifier",
+  invalidParentForThisNode:
+    "We don't know how to handle this node within the current parent - please open an issue",
   readOnly: "$1 is read-only",
   unknownForHead: "Unknown node type $1 in ForStatement",
   didYouMean: "Did you mean $1?",
-  codeGeneratorDeopt: "Note: The code generator has deoptimised the styling of $1 as it exceeds the max of $2.",
-  missingTemplatesDirectory: "no templates directory - this is most likely the result of a broken `npm publish`. Please report to https://github.com/babel/babel/issues",
+  codeGeneratorDeopt:
+    "Note: The code generator has deoptimised the styling of $1 as it exceeds the max of $2.",
+  missingTemplatesDirectory:
+    "no templates directory - this is most likely the result of a broken `npm publish`. Please report to https://github.com/babel/babel/issues",
   unsupportedOutputType: "Unsupported output type $1",
   illegalMethodName: "Illegal method name $1",
-  lostTrackNodePath: "We lost track of this node's position, likely because the AST was directly manipulated",
+  lostTrackNodePath:
+    "We lost track of this node's position, likely because the AST was directly manipulated",
 
   modulesIllegalExportName: "Illegal export $1",
-  modulesDuplicateDeclarations: "Duplicate module declarations with the same source but in different scopes",
+  modulesDuplicateDeclarations:
+    "Duplicate module declarations with the same source but in different scopes",
 
   undeclaredVariable: "Reference to undeclared variable $1",
-  undeclaredVariableType: "Referencing a type alias outside of a type annotation",
-  undeclaredVariableSuggestion: "Reference to undeclared variable $1 - did you mean $2?",
+  undeclaredVariableType:
+    "Referencing a type alias outside of a type annotation",
+  undeclaredVariableSuggestion:
+    "Reference to undeclared variable $1 - did you mean $2?",
 
-  traverseNeedsParent: "You must pass a scope and parentPath unless traversing a Program/File. Instead of that you tried to traverse a $1 node without passing scope and parentPath.",
-  traverseVerifyRootFunction: "You passed `traverse()` a function when it expected a visitor object, are you sure you didn't mean `{ enter: Function }`?",
-  traverseVerifyVisitorProperty: "You passed `traverse()` a visitor object with the property $1 that has the invalid property $2",
-  traverseVerifyNodeType: "You gave us a visitor for the node type $1 but it's not a valid type",
+  traverseNeedsParent:
+    "You must pass a scope and parentPath unless traversing a Program/File. Instead of that you tried to traverse a $1 node without passing scope and parentPath.",
+  traverseVerifyRootFunction:
+    "You passed `traverse()` a function when it expected a visitor object, are you sure you didn't mean `{ enter: Function }`?",
+  traverseVerifyVisitorProperty:
+    "You passed `traverse()` a visitor object with the property $1 that has the invalid property $2",
+  traverseVerifyNodeType:
+    "You gave us a visitor for the node type $1 but it's not a valid type",
 
-  pluginNotObject: "Plugin $2 specified in $1 was expected to return an object when invoked but returned $3",
-  pluginNotFunction: "Plugin $2 specified in $1 was expected to return a function but returned $3",
-  pluginUnknown: "Unknown plugin $1 specified in $2 at $3, attempted to resolve relative to $4",
+  pluginNotObject:
+    "Plugin $2 specified in $1 was expected to return an object when invoked but returned $3",
+  pluginNotFunction:
+    "Plugin $2 specified in $1 was expected to return a function but returned $3",
+  pluginUnknown:
+    "Unknown plugin $1 specified in $2 at $3, attempted to resolve relative to $4",
   pluginInvalidProperty: "Plugin $1 provided an invalid property of $2",
 };
 
@@ -55,7 +72,7 @@ export function get(key: string, ...args: Array<any>): string {
   args = parseArgs(args);
 
   // replace $0 placeholders with args
-  return msg.replace(/\$(\d+)/g, function (str, i) {
+  return msg.replace(/\$(\d+)/g, function(str, i) {
     return args[i - 1];
   });
 }
@@ -65,7 +82,7 @@ export function get(key: string, ...args: Array<any>): string {
  */
 
 export function parseArgs(args: Array<any>): Array<string> {
-  return args.map(function (val) {
+  return args.map(function(val) {
     if (val != null && val.inspect) {
       return val.inspect();
     } else {
diff --git a/packages/babel-plugin-check-es2015-constants/src/index.js b/packages/babel-plugin-check-es2015-constants/src/index.js
index ccc79b1b16..814290f4ef 100644
--- a/packages/babel-plugin-check-es2015-constants/src/index.js
+++ b/packages/babel-plugin-check-es2015-constants/src/index.js
@@ -1,4 +1,4 @@
-export default function ({ messages }) {
+export default function({ messages }) {
   return {
     visitor: {
       Scope({ scope }) {
diff --git a/packages/babel-plugin-external-helpers/src/index.js b/packages/babel-plugin-external-helpers/src/index.js
index 5bc3235f86..0f0945621c 100644
--- a/packages/babel-plugin-external-helpers/src/index.js
+++ b/packages/babel-plugin-external-helpers/src/index.js
@@ -1,4 +1,4 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   return {
     pre(file) {
       file.set("helpersNamespace", t.identifier("babelHelpers"));
diff --git a/packages/babel-plugin-syntax-async-functions/src/index.js b/packages/babel-plugin-syntax-async-functions/src/index.js
index 11939db7dd..bf3d3a16f4 100644
--- a/packages/babel-plugin-syntax-async-functions/src/index.js
+++ b/packages/babel-plugin-syntax-async-functions/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("asyncFunctions");
diff --git a/packages/babel-plugin-syntax-async-generators/src/index.js b/packages/babel-plugin-syntax-async-generators/src/index.js
index 9bccbfa57a..f94586ed81 100644
--- a/packages/babel-plugin-syntax-async-generators/src/index.js
+++ b/packages/babel-plugin-syntax-async-generators/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("asyncGenerators");
diff --git a/packages/babel-plugin-syntax-class-properties/src/index.js b/packages/babel-plugin-syntax-class-properties/src/index.js
index 481b7be1e8..496f07c664 100644
--- a/packages/babel-plugin-syntax-class-properties/src/index.js
+++ b/packages/babel-plugin-syntax-class-properties/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("classProperties");
diff --git a/packages/babel-plugin-syntax-decorators/src/index.js b/packages/babel-plugin-syntax-decorators/src/index.js
index 8bd18d37b7..f29917451a 100644
--- a/packages/babel-plugin-syntax-decorators/src/index.js
+++ b/packages/babel-plugin-syntax-decorators/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("decorators");
diff --git a/packages/babel-plugin-syntax-do-expressions/src/index.js b/packages/babel-plugin-syntax-do-expressions/src/index.js
index bb09f4c9f5..2b91fd23fd 100644
--- a/packages/babel-plugin-syntax-do-expressions/src/index.js
+++ b/packages/babel-plugin-syntax-do-expressions/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("doExpressions");
diff --git a/packages/babel-plugin-syntax-dynamic-import/src/index.js b/packages/babel-plugin-syntax-dynamic-import/src/index.js
index ebcaaa4a19..bac1815edc 100644
--- a/packages/babel-plugin-syntax-dynamic-import/src/index.js
+++ b/packages/babel-plugin-syntax-dynamic-import/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("dynamicImport");
diff --git a/packages/babel-plugin-syntax-exponentiation-operator/src/index.js b/packages/babel-plugin-syntax-exponentiation-operator/src/index.js
index a8001e291c..f02f261183 100644
--- a/packages/babel-plugin-syntax-exponentiation-operator/src/index.js
+++ b/packages/babel-plugin-syntax-exponentiation-operator/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("exponentiationOperator");
diff --git a/packages/babel-plugin-syntax-export-extensions/src/index.js b/packages/babel-plugin-syntax-export-extensions/src/index.js
index b2a6727fce..cfacda7da1 100644
--- a/packages/babel-plugin-syntax-export-extensions/src/index.js
+++ b/packages/babel-plugin-syntax-export-extensions/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("exportExtensions");
diff --git a/packages/babel-plugin-syntax-flow/src/index.js b/packages/babel-plugin-syntax-flow/src/index.js
index 01890b3618..0043b1455f 100644
--- a/packages/babel-plugin-syntax-flow/src/index.js
+++ b/packages/babel-plugin-syntax-flow/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("flow");
diff --git a/packages/babel-plugin-syntax-function-bind/src/index.js b/packages/babel-plugin-syntax-function-bind/src/index.js
index 3f05d86ff4..31ddfa50c6 100644
--- a/packages/babel-plugin-syntax-function-bind/src/index.js
+++ b/packages/babel-plugin-syntax-function-bind/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("functionBind");
diff --git a/packages/babel-plugin-syntax-function-sent/src/index.js b/packages/babel-plugin-syntax-function-sent/src/index.js
index f336b24077..9481f1983a 100644
--- a/packages/babel-plugin-syntax-function-sent/src/index.js
+++ b/packages/babel-plugin-syntax-function-sent/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("functionSent");
diff --git a/packages/babel-plugin-syntax-jsx/src/index.js b/packages/babel-plugin-syntax-jsx/src/index.js
index e7d1697f3d..eb8986ab28 100644
--- a/packages/babel-plugin-syntax-jsx/src/index.js
+++ b/packages/babel-plugin-syntax-jsx/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("jsx");
diff --git a/packages/babel-plugin-syntax-numeric-separator/src/index.js b/packages/babel-plugin-syntax-numeric-separator/src/index.js
index 751844a69b..7d7fbd4f74 100644
--- a/packages/babel-plugin-syntax-numeric-separator/src/index.js
+++ b/packages/babel-plugin-syntax-numeric-separator/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("numericSeparator");
diff --git a/packages/babel-plugin-syntax-object-rest-spread/src/index.js b/packages/babel-plugin-syntax-object-rest-spread/src/index.js
index 5353e63eed..6eb03aa819 100644
--- a/packages/babel-plugin-syntax-object-rest-spread/src/index.js
+++ b/packages/babel-plugin-syntax-object-rest-spread/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("objectRestSpread");
diff --git a/packages/babel-plugin-syntax-optional-chaining/index.js b/packages/babel-plugin-syntax-optional-chaining/index.js
index 37e4c8f53d..76d014a88a 100644
--- a/packages/babel-plugin-syntax-optional-chaining/index.js
+++ b/packages/babel-plugin-syntax-optional-chaining/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("optionalChaining");
diff --git a/packages/babel-plugin-syntax-trailing-function-commas/src/index.js b/packages/babel-plugin-syntax-trailing-function-commas/src/index.js
index 29d5031933..f8b532096b 100644
--- a/packages/babel-plugin-syntax-trailing-function-commas/src/index.js
+++ b/packages/babel-plugin-syntax-trailing-function-commas/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("trailingFunctionCommas");
diff --git a/packages/babel-plugin-transform-async-functions/src/index.js b/packages/babel-plugin-transform-async-functions/src/index.js
index 20eb9f453b..a4a1b0e8d2 100644
--- a/packages/babel-plugin-transform-async-functions/src/index.js
+++ b/packages/babel-plugin-transform-async-functions/src/index.js
@@ -1,6 +1,6 @@
 import asyncSyntaxPlugin from "babel-plugin-syntax-async-functions";
 
-export default function () {
+export default function() {
   return {
     inherits: asyncSyntaxPlugin,
   };
diff --git a/packages/babel-plugin-transform-async-generator-functions/src/index.js b/packages/babel-plugin-transform-async-generator-functions/src/index.js
index ebd5903e1d..36c5bff914 100644
--- a/packages/babel-plugin-transform-async-generator-functions/src/index.js
+++ b/packages/babel-plugin-transform-async-generator-functions/src/index.js
@@ -1,7 +1,7 @@
 import remapAsyncToGenerator from "babel-helper-remap-async-to-generator";
 import syntaxAsyncGenerators from "babel-plugin-syntax-async-generators";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   const yieldStarVisitor = {
     Function(path) {
       path.skip();
@@ -12,7 +12,10 @@ export default function ({ types: t }) {
       const callee = state.addHelper("asyncGeneratorDelegate");
       node.argument = t.callExpression(callee, [
         t.callExpression(state.addHelper("asyncIterator"), [node.argument]),
-        t.memberExpression(state.addHelper("asyncGenerator"), t.identifier("await")),
+        t.memberExpression(
+          state.addHelper("asyncGenerator"),
+          t.identifier("await"),
+        ),
       ]);
     },
   };
@@ -27,9 +30,13 @@ export default function ({ types: t }) {
 
         remapAsyncToGenerator(path, state.file, {
           wrapAsync: t.memberExpression(
-            state.addHelper("asyncGenerator"), t.identifier("wrap")),
+            state.addHelper("asyncGenerator"),
+            t.identifier("wrap"),
+          ),
           wrapAwait: t.memberExpression(
-            state.addHelper("asyncGenerator"), t.identifier("await")),
+            state.addHelper("asyncGenerator"),
+            t.identifier("await"),
+          ),
         });
       },
     },
diff --git a/packages/babel-plugin-transform-async-to-generator/src/index.js b/packages/babel-plugin-transform-async-to-generator/src/index.js
index 27e92a5ec7..b562491405 100644
--- a/packages/babel-plugin-transform-async-to-generator/src/index.js
+++ b/packages/babel-plugin-transform-async-to-generator/src/index.js
@@ -1,7 +1,7 @@
 import remapAsyncToGenerator from "babel-helper-remap-async-to-generator";
 import syntaxAsyncFunctions from "babel-plugin-syntax-async-functions";
 
-export default function () {
+export default function() {
   return {
     inherits: syntaxAsyncFunctions,
 
diff --git a/packages/babel-plugin-transform-async-to-module-method/src/index.js b/packages/babel-plugin-transform-async-to-module-method/src/index.js
index 51a0ab4089..1eda016ef5 100644
--- a/packages/babel-plugin-transform-async-to-module-method/src/index.js
+++ b/packages/babel-plugin-transform-async-to-module-method/src/index.js
@@ -1,7 +1,7 @@
 import remapAsyncToGenerator from "babel-helper-remap-async-to-generator";
 import syntaxAsyncFunctions from "babel-plugin-syntax-async-functions";
 
-export default function () {
+export default function() {
   return {
     inherits: syntaxAsyncFunctions,
 
diff --git a/packages/babel-plugin-transform-class-properties/src/index.js b/packages/babel-plugin-transform-class-properties/src/index.js
index 5d58f767e6..1a3753e890 100644
--- a/packages/babel-plugin-transform-class-properties/src/index.js
+++ b/packages/babel-plugin-transform-class-properties/src/index.js
@@ -2,7 +2,7 @@ import nameFunction from "babel-helper-function-name";
 import template from "babel-template";
 import syntaxClassProperties from "babel-plugin-syntax-class-properties";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   const findBareSupers = {
     Super(path) {
       if (path.parentPath.isCallExpression({ callee: path.node })) {
@@ -29,23 +29,30 @@ export default function ({ types: t }) {
     });
   `);
 
-  const buildClassPropertySpec = (ref, { key, value, computed }) => buildObjectDefineProperty({
-    REF: ref,
-    KEY: (t.isIdentifier(key) && !computed) ? t.stringLiteral(key.name) : key,
-    VALUE: value ? value : t.identifier("undefined"),
-  });
+  const buildClassPropertySpec = (ref, { key, value, computed }) =>
+    buildObjectDefineProperty({
+      REF: ref,
+      KEY: t.isIdentifier(key) && !computed ? t.stringLiteral(key.name) : key,
+      VALUE: value ? value : t.identifier("undefined"),
+    });
 
-  const buildClassPropertyNonSpec = (ref, { key, value, computed }) => t.expressionStatement(
-    t.assignmentExpression("=", t.memberExpression(ref, key, computed || t.isLiteral(key)), value)
-  );
+  const buildClassPropertyNonSpec = (ref, { key, value, computed }) =>
+    t.expressionStatement(
+      t.assignmentExpression(
+        "=",
+        t.memberExpression(ref, key, computed || t.isLiteral(key)),
+        value,
+      ),
+    );
 
   return {
     inherits: syntaxClassProperties,
 
     visitor: {
       Class(path, state) {
-        const buildClassProperty = state.opts.spec ? buildClassPropertySpec :
-          buildClassPropertyNonSpec;
+        const buildClassProperty = state.opts.spec
+          ? buildClassPropertySpec
+          : buildClassPropertyNonSpec;
         const isDerived = !!path.node.superClass;
         let constructor;
         const props = [];
@@ -67,7 +74,8 @@ export default function ({ types: t }) {
         if (path.isClassExpression() || !path.node.id) {
           nameFunction(path);
           ref = path.scope.generateUidIdentifier("class");
-        } else { // path.isClassDeclaration() && path.node.id
+        } else {
+          // path.isClassDeclaration() && path.node.id
           ref = path.node.id;
         }
 
@@ -93,17 +101,20 @@ export default function ({ types: t }) {
 
         if (instanceBody.length) {
           if (!constructor) {
-            const newConstructor = t.classMethod("constructor", t.identifier("constructor"), [],
-              t.blockStatement([]));
+            const newConstructor = t.classMethod(
+              "constructor",
+              t.identifier("constructor"),
+              [],
+              t.blockStatement([]),
+            );
             if (isDerived) {
               newConstructor.params = [t.restElement(t.identifier("args"))];
               newConstructor.body.body.push(
                 t.returnStatement(
-                  t.callExpression(
-                    t.super(),
-                    [t.spreadElement(t.identifier("args"))]
-                  )
-                )
+                  t.callExpression(t.super(), [
+                    t.spreadElement(t.identifier("args")),
+                  ]),
+                ),
               );
             }
             [constructor] = body.unshiftContainer("body", newConstructor);
@@ -120,19 +131,29 @@ export default function ({ types: t }) {
           }
 
           if (collisionState.collision) {
-            const initialisePropsRef = path.scope.generateUidIdentifier("initialiseProps");
+            const initialisePropsRef = path.scope.generateUidIdentifier(
+              "initialiseProps",
+            );
 
-            nodes.push(t.variableDeclaration("var", [
-              t.variableDeclarator(
-                initialisePropsRef,
-                t.functionExpression(null, [], t.blockStatement(instanceBody))
-              ),
-            ]));
+            nodes.push(
+              t.variableDeclaration("var", [
+                t.variableDeclarator(
+                  initialisePropsRef,
+                  t.functionExpression(
+                    null,
+                    [],
+                    t.blockStatement(instanceBody),
+                  ),
+                ),
+              ]),
+            );
 
             instanceBody = [
               t.expressionStatement(
-                t.callExpression(t.memberExpression(initialisePropsRef, t.identifier("call")), [
-                  t.thisExpression()])
+                t.callExpression(
+                  t.memberExpression(initialisePropsRef, t.identifier("call")),
+                  [t.thisExpression()],
+                ),
               ),
             ];
           }
@@ -159,7 +180,8 @@ export default function ({ types: t }) {
         if (path.isClassExpression()) {
           path.scope.push({ id: ref });
           path.replaceWith(t.assignmentExpression("=", ref, path.node));
-        } else { // path.isClassDeclaration()
+        } else {
+          // path.isClassDeclaration()
           if (!path.node.id) {
             path.node.id = ref;
           }
@@ -177,7 +199,7 @@ export default function ({ types: t }) {
 
         const body = classExp.get("body");
         const members = body.get("body");
-        if (members.some((member) => member.isClassProperty())) {
+        if (members.some(member => member.isClassProperty())) {
           path.ensureBlock();
         }
       },
diff --git a/packages/babel-plugin-transform-decorators/src/index.js b/packages/babel-plugin-transform-decorators/src/index.js
index 700bc50259..05d589b5aa 100644
--- a/packages/babel-plugin-transform-decorators/src/index.js
+++ b/packages/babel-plugin-transform-decorators/src/index.js
@@ -15,7 +15,6 @@ const buildGetDescriptor = template(`
     Object.getOwnPropertyDescriptor(TARGET, PROPERTY);
 `);
 
-
 const buildGetObjectInitializer = template(`
     (TEMP = Object.getOwnPropertyDescriptor(TARGET, PROPERTY), (TEMP = TEMP ? TEMP.value : undefined), {
         enumerable: true,
@@ -88,7 +87,9 @@ export default function({ types: t }) {
    */
   function ensureApplyDecoratedDescriptorHelper(path, state) {
     if (!state.applyDecoratedDescriptor) {
-      state.applyDecoratedDescriptor = path.scope.generateUidIdentifier("applyDecoratedDescriptor");
+      state.applyDecoratedDescriptor = path.scope.generateUidIdentifier(
+        "applyDecoratedDescriptor",
+      );
       const helper = buildApplyDecoratedDescriptor({
         NAME: state.applyDecoratedDescriptor,
       });
@@ -103,7 +104,9 @@ export default function({ types: t }) {
    */
   function ensureInitializerDefineProp(path, state) {
     if (!state.initializerDefineProp) {
-      state.initializerDefineProp = path.scope.generateUidIdentifier("initDefineProp");
+      state.initializerDefineProp = path.scope.generateUidIdentifier(
+        "initDefineProp",
+      );
       const helper = buildInitializerDefineProperty({
         NAME: state.initializerDefineProp,
       });
@@ -119,7 +122,9 @@ export default function({ types: t }) {
    */
   function ensureInitializerWarning(path, state) {
     if (!state.initializerWarningHelper) {
-      state.initializerWarningHelper = path.scope.generateUidIdentifier("initializerWarningHelper");
+      state.initializerWarningHelper = path.scope.generateUidIdentifier(
+        "initializerWarningHelper",
+      );
       const helper = buildInitializerWarningHelper({
         NAME: state.initializerWarningHelper,
       });
@@ -135,20 +140,29 @@ export default function({ types: t }) {
    */
   function applyEnsureOrdering(path) {
     // TODO: This should probably also hoist computed properties.
-    const decorators = (
-      path.isClass()
+    const decorators = (path.isClass()
       ? [path].concat(path.get("body.body"))
-      : path.get("properties")
-    ).reduce((acc, prop) => acc.concat(prop.node.decorators || []), []);
+      : path.get("properties")).reduce(
+      (acc, prop) => acc.concat(prop.node.decorators || []),
+      [],
+    );
 
-    const identDecorators = decorators.filter((decorator) => !t.isIdentifier(decorator.expression));
+    const identDecorators = decorators.filter(
+      decorator => !t.isIdentifier(decorator.expression),
+    );
     if (identDecorators.length === 0) return;
 
-    return t.sequenceExpression(identDecorators.map((decorator) => {
-      const expression = decorator.expression;
-      const id = decorator.expression = path.scope.generateDeclaredUidIdentifier("dec");
-      return t.assignmentExpression("=", id, expression);
-    }).concat([path.node]));
+    return t.sequenceExpression(
+      identDecorators
+        .map(decorator => {
+          const expression = decorator.expression;
+          const id = (decorator.expression = path.scope.generateDeclaredUidIdentifier(
+            "dec",
+          ));
+          return t.assignmentExpression("=", id, expression);
+        })
+        .concat([path.node]),
+    );
   }
 
   /**
@@ -164,15 +178,15 @@ export default function({ types: t }) {
     const name = classPath.scope.generateDeclaredUidIdentifier("class");
 
     return decorators
-            .map((dec) => dec.expression)
-            .reverse()
-            .reduce(function(acc, decorator) {
-              return buildClassDecorator({
-                CLASS_REF: name,
-                DECORATOR: decorator,
-                INNER: acc,
-              }).expression;
-            }, classPath.node);
+      .map(dec => dec.expression)
+      .reverse()
+      .reduce(function(acc, decorator) {
+        return buildClassDecorator({
+          CLASS_REF: name,
+          DECORATOR: decorator,
+          INNER: acc,
+        }).expression;
+      }, classPath.node);
   }
 
   /**
@@ -207,7 +221,9 @@ export default function({ types: t }) {
    * A helper to pull out property decorators into a sequence expression.
    */
   function applyTargetDecorators(path, state, decoratedProps) {
-    const name = path.scope.generateDeclaredUidIdentifier(path.isClass() ? "class" : "obj");
+    const name = path.scope.generateDeclaredUidIdentifier(
+      path.isClass() ? "class" : "obj",
+    );
 
     const exprs = decoratedProps.reduce(function(acc, node) {
       const decorators = node.decorators || [];
@@ -216,58 +232,79 @@ export default function({ types: t }) {
       if (decorators.length === 0) return acc;
 
       if (node.computed) {
-        throw path.buildCodeFrameError("Computed method/property decorators are not yet supported.");
+        throw path.buildCodeFrameError(
+          "Computed method/property decorators are not yet supported.",
+        );
       }
 
-      const property = t.isLiteral(node.key) ? node.key : t.stringLiteral(node.key.name);
+      const property = t.isLiteral(node.key)
+        ? node.key
+        : t.stringLiteral(node.key.name);
 
-      const target = (path.isClass() && !node.static) ? buildClassPrototype({
-        CLASS_REF: name,
-      }).expression : name;
+      const target =
+        path.isClass() && !node.static
+          ? buildClassPrototype({
+              CLASS_REF: name,
+            }).expression
+          : name;
 
       if (t.isClassProperty(node, { static: false })) {
-        const descriptor = path.scope.generateDeclaredUidIdentifier("descriptor");
-
-        const initializer = node.value ?
-                        t.functionExpression(null, [], t.blockStatement([t.returnStatement(node.value)])) :
-                        t.nullLiteral();
-        node.value = t.callExpression(
-          ensureInitializerWarning(path, state), [descriptor, t.thisExpression()]
+        const descriptor = path.scope.generateDeclaredUidIdentifier(
+          "descriptor",
         );
 
+        const initializer = node.value
+          ? t.functionExpression(
+              null,
+              [],
+              t.blockStatement([t.returnStatement(node.value)]),
+            )
+          : t.nullLiteral();
+        node.value = t.callExpression(ensureInitializerWarning(path, state), [
+          descriptor,
+          t.thisExpression(),
+        ]);
+
         acc = acc.concat([
           t.assignmentExpression(
-            "=", descriptor, t.callExpression(ensureApplyDecoratedDescriptorHelper(path, state), [
-              target,
-              property,
-              t.arrayExpression(decorators.map((dec) => dec.expression)),
-              t.objectExpression([
-                t.objectProperty(t.identifier("enumerable"), t.booleanLiteral(true)),
-                t.objectProperty(t.identifier("initializer"), initializer),
-              ]),
-            ])
+            "=",
+            descriptor,
+            t.callExpression(
+              ensureApplyDecoratedDescriptorHelper(path, state),
+              [
+                target,
+                property,
+                t.arrayExpression(decorators.map(dec => dec.expression)),
+                t.objectExpression([
+                  t.objectProperty(
+                    t.identifier("enumerable"),
+                    t.booleanLiteral(true),
+                  ),
+                  t.objectProperty(t.identifier("initializer"), initializer),
+                ]),
+              ],
+            ),
           ),
         ]);
       } else {
         acc = acc.concat(
-            t.callExpression(ensureApplyDecoratedDescriptorHelper(path, state), [
-              target,
-              property,
-              t.arrayExpression(decorators.map((dec) => dec.expression)),
-              (
-                t.isObjectProperty(node) ||
-                t.isClassProperty(node, { static: true })) ?
-                buildGetObjectInitializer({
+          t.callExpression(ensureApplyDecoratedDescriptorHelper(path, state), [
+            target,
+            property,
+            t.arrayExpression(decorators.map(dec => dec.expression)),
+            t.isObjectProperty(node) ||
+            t.isClassProperty(node, { static: true })
+              ? buildGetObjectInitializer({
                   TEMP: path.scope.generateDeclaredUidIdentifier("init"),
                   TARGET: target,
                   PROPERTY: property,
-                }).expression : buildGetDescriptor({
+                }).expression
+              : buildGetDescriptor({
                   TARGET: target,
                   PROPERTY: property,
-                }
-              ).expression,
-              target,
-            ])
+                }).expression,
+            target,
+          ]),
         );
       }
 
@@ -289,35 +326,42 @@ export default function({ types: t }) {
         if (!path.get("declaration").isClassDeclaration()) return;
 
         const { node } = path;
-        const ref = node.declaration.id || path.scope.generateUidIdentifier("default");
+        const ref =
+          node.declaration.id || path.scope.generateUidIdentifier("default");
         node.declaration.id = ref;
 
         // Split the class declaration and the export into two separate statements.
         path.replaceWith(node.declaration);
-        path.insertAfter(t.exportNamedDeclaration(null, [t.exportSpecifier(ref, t.identifier("default"))]));
+        path.insertAfter(
+          t.exportNamedDeclaration(null, [
+            t.exportSpecifier(ref, t.identifier("default")),
+          ]),
+        );
       },
       ClassDeclaration(path) {
         const { node } = path;
 
         const ref = node.id || path.scope.generateUidIdentifier("class");
 
-        path.replaceWith(t.variableDeclaration("let", [
-          t.variableDeclarator(ref, t.toExpression(node)),
-        ]));
+        path.replaceWith(
+          t.variableDeclaration("let", [
+            t.variableDeclarator(ref, t.toExpression(node)),
+          ]),
+        );
       },
       ClassExpression(path, state) {
         // Create a replacement for the class node if there is one. We do one pass to replace classes with
         // class decorators, and a second pass to process method decorators.
-        const decoratedClass = (
+        const decoratedClass =
           applyEnsureOrdering(path) ||
           applyClassDecorators(path, state) ||
-          applyMethodDecorators(path, state)
-        );
+          applyMethodDecorators(path, state);
 
         if (decoratedClass) path.replaceWith(decoratedClass);
       },
       ObjectExpression(path, state) {
-        const decoratedObject = applyEnsureOrdering(path) || applyObjectDecorators(path, state);
+        const decoratedObject =
+          applyEnsureOrdering(path) || applyObjectDecorators(path, state);
 
         if (decoratedObject) path.replaceWith(decoratedObject);
       },
@@ -328,14 +372,22 @@ export default function({ types: t }) {
         if (!path.get("left").isMemberExpression()) return;
         if (!path.get("left.property").isIdentifier()) return;
         if (!path.get("right").isCallExpression()) return;
-        if (!path.get("right.callee").isIdentifier({ name: state.initializerWarningHelper.name })) return;
+        if (
+          !path
+            .get("right.callee")
+            .isIdentifier({ name: state.initializerWarningHelper.name })
+        ) {
+          return;
+        }
 
-        path.replaceWith(t.callExpression(ensureInitializerDefineProp(path, state), [
-          path.get("left.object").node,
-          t.stringLiteral(path.get("left.property").node.name),
-          path.get("right.arguments")[0].node,
-          path.get("right.arguments")[1].node,
-        ]));
+        path.replaceWith(
+          t.callExpression(ensureInitializerDefineProp(path, state), [
+            path.get("left.object").node,
+            t.stringLiteral(path.get("left.property").node.name),
+            path.get("right.arguments")[0].node,
+            path.get("right.arguments")[1].node,
+          ]),
+        );
       },
     },
   };
diff --git a/packages/babel-plugin-transform-do-expressions/src/index.js b/packages/babel-plugin-transform-do-expressions/src/index.js
index bc44bfde04..9b164971e3 100644
--- a/packages/babel-plugin-transform-do-expressions/src/index.js
+++ b/packages/babel-plugin-transform-do-expressions/src/index.js
@@ -1,6 +1,6 @@
 import syntaxDoExpressions from "babel-plugin-syntax-do-expressions";
 
-export default function () {
+export default function() {
   return {
     inherits: syntaxDoExpressions,
 
diff --git a/packages/babel-plugin-transform-es2015-arrow-functions/src/index.js b/packages/babel-plugin-transform-es2015-arrow-functions/src/index.js
index 3009e83c84..996b2752df 100644
--- a/packages/babel-plugin-transform-es2015-arrow-functions/src/index.js
+++ b/packages/babel-plugin-transform-es2015-arrow-functions/src/index.js
@@ -2,10 +2,13 @@
 
 import type NodePath from "babel-traverse";
 
-export default function () {
+export default function() {
   return {
     visitor: {
-      ArrowFunctionExpression(path: NodePath<BabelNodeArrowFunctionExpression>, state: Object) {
+      ArrowFunctionExpression(
+        path: NodePath<BabelNodeArrowFunctionExpression>,
+        state: Object,
+      ) {
         // In some conversion cases, it may have already been converted to a function while this callback
         // was queued up.
         if (!path.isArrowFunctionExpression()) return;
diff --git a/packages/babel-plugin-transform-es2015-block-scoped-functions/src/index.js b/packages/babel-plugin-transform-es2015-block-scoped-functions/src/index.js
index dad07b0db7..d882437a30 100644
--- a/packages/babel-plugin-transform-es2015-block-scoped-functions/src/index.js
+++ b/packages/babel-plugin-transform-es2015-block-scoped-functions/src/index.js
@@ -1,4 +1,4 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function statementList(key, path) {
     const paths: Array = path.get(key);
 
@@ -24,7 +24,10 @@ export default function ({ types: t }) {
     visitor: {
       BlockStatement(path) {
         const { node, parent } = path;
-        if (t.isFunction(parent, { body: node }) || t.isExportDeclaration(parent)) {
+        if (
+          t.isFunction(parent, { body: node }) ||
+          t.isExportDeclaration(parent)
+        ) {
           return;
         }
 
diff --git a/packages/babel-plugin-transform-es2015-block-scoping/src/index.js b/packages/babel-plugin-transform-es2015-block-scoping/src/index.js
index 0eaf8a2666..c21b661b9d 100644
--- a/packages/babel-plugin-transform-es2015-block-scoping/src/index.js
+++ b/packages/babel-plugin-transform-es2015-block-scoping/src/index.js
@@ -8,7 +8,7 @@ import values from "lodash/values";
 import extend from "lodash/extend";
 import template from "babel-template";
 
-export default function () {
+export default function() {
   return {
     visitor: {
       VariableDeclaration(path, file) {
@@ -44,20 +44,38 @@ export default function () {
       Loop(path, file) {
         const { node, parent, scope } = path;
         t.ensureBlock(node);
-        const blockScoping = new BlockScoping(path, path.get("body"), parent, scope, file);
+        const blockScoping = new BlockScoping(
+          path,
+          path.get("body"),
+          parent,
+          scope,
+          file,
+        );
         const replace = blockScoping.run();
         if (replace) path.replaceWith(replace);
       },
 
       CatchClause(path, file) {
         const { parent, scope } = path;
-        const blockScoping = new BlockScoping(null, path.get("body"), parent, scope, file);
+        const blockScoping = new BlockScoping(
+          null,
+          path.get("body"),
+          parent,
+          scope,
+          file,
+        );
         blockScoping.run();
       },
 
       "BlockStatement|SwitchStatement|Program"(path, file) {
         if (!ignoreBlock(path)) {
-          const blockScoping = new BlockScoping(null, path, path.parent, path.scope, file);
+          const blockScoping = new BlockScoping(
+            null,
+            path,
+            path.parent,
+            path.scope,
+            file,
+          );
           blockScoping.run();
         }
       },
@@ -80,7 +98,13 @@ function isBlockScoped(node) {
   return true;
 }
 
-function convertBlockScopedToVar(path, node, parent, scope, moveBindingsToParent = false) {
+function convertBlockScopedToVar(
+  path,
+  node,
+  parent,
+  scope,
+  moveBindingsToParent = false,
+) {
   if (!node) {
     node = path.node;
   }
@@ -111,41 +135,47 @@ function isVar(node) {
   return t.isVariableDeclaration(node, { kind: "var" }) && !isBlockScoped(node);
 }
 
-const letReferenceBlockVisitor = traverse.visitors.merge([{
-  Loop: {
-    enter(path, state) {
-      state.loopDepth++;
+const letReferenceBlockVisitor = traverse.visitors.merge([
+  {
+    Loop: {
+      enter(path, state) {
+        state.loopDepth++;
+      },
+      exit(path, state) {
+        state.loopDepth--;
+      },
     },
-    exit(path, state) {
-      state.loopDepth--;
+    Function(path, state) {
+      // References to block-scoped variables only require added closures if it's
+      // possible for the code to run more than once -- otherwise it is safe to
+      // simply rename the variables.
+      if (state.loopDepth > 0) {
+        path.traverse(letReferenceFunctionVisitor, state);
+      }
+      return path.skip();
     },
   },
-  Function(path, state) {
-    // References to block-scoped variables only require added closures if it's
-    // possible for the code to run more than once -- otherwise it is safe to
-    // simply rename the variables.
-    if (state.loopDepth > 0) {
-      path.traverse(letReferenceFunctionVisitor, state);
-    }
-    return path.skip();
+  tdzVisitor,
+]);
+
+const letReferenceFunctionVisitor = traverse.visitors.merge([
+  {
+    ReferencedIdentifier(path, state) {
+      const ref = state.letReferences[path.node.name];
+
+      // not a part of our scope
+      if (!ref) return;
+
+      // this scope has a variable with the same name so it couldn't belong
+      // to our let scope
+      const localBinding = path.scope.getBindingIdentifier(path.node.name);
+      if (localBinding && localBinding !== ref) return;
+
+      state.closurify = true;
+    },
   },
-}, tdzVisitor]);
-
-const letReferenceFunctionVisitor = traverse.visitors.merge([{
-  ReferencedIdentifier(path, state) {
-    const ref = state.letReferences[path.node.name];
-
-    // not a part of our scope
-    if (!ref) return;
-
-    // this scope has a variable with the same name so it couldn't belong
-    // to our let scope
-    const localBinding = path.scope.getBindingIdentifier(path.node.name);
-    if (localBinding && localBinding !== ref) return;
-
-    state.closurify = true;
-  },
-}, tdzVisitor]);
+  tdzVisitor,
+]);
 
 const hoistVarDeclarationsVisitor = {
   enter(path, self) {
@@ -166,7 +196,9 @@ const hoistVarDeclarationsVisitor = {
         node.left = node.left.declarations[0].id;
       }
     } else if (isVar(node, parent)) {
-      path.replaceWithMultiple(self.pushDeclar(node).map((expr) => t.expressionStatement(expr)));
+      path.replaceWithMultiple(
+        self.pushDeclar(node).map(expr => t.expressionStatement(expr)),
+      );
     } else if (path.isFunction()) {
       return path.skip();
     }
@@ -184,7 +216,12 @@ const continuationVisitor = {
     if (path.isAssignmentExpression() || path.isUpdateExpression()) {
       const bindings = path.getBindingIdentifiers();
       for (const name in bindings) {
-        if (state.outsideReferences[name] !== path.scope.getBindingIdentifier(name)) continue;
+        if (
+          state.outsideReferences[name] !==
+          path.scope.getBindingIdentifier(name)
+        ) {
+          continue;
+        }
         state.reassignments[name] = true;
       }
     }
@@ -252,7 +289,10 @@ const loopVisitor = {
     if (path.isReturnStatement()) {
       state.hasReturn = true;
       replace = t.objectExpression([
-        t.objectProperty(t.identifier("v"), node.argument || scope.buildUndefinedNode()),
+        t.objectProperty(
+          t.identifier("v"),
+          node.argument || scope.buildUndefinedNode(),
+        ),
       ]);
     }
 
@@ -266,7 +306,13 @@ const loopVisitor = {
 };
 
 class BlockScoping {
-  constructor(loopPath?: NodePath, blockPath: NodePath, parent: Object, scope: Scope, file: File) {
+  constructor(
+    loopPath?: NodePath,
+    blockPath: NodePath,
+    parent: Object,
+    scope: Scope,
+    file: File,
+  ) {
     this.parent = parent;
     this.scope = scope;
     this.file = file;
@@ -281,7 +327,8 @@ class BlockScoping {
 
     if (loopPath) {
       this.loopParent = loopPath.parent;
-      this.loopLabel = t.isLabeledStatement(this.loopParent) && this.loopParent.label;
+      this.loopLabel =
+        t.isLabeledStatement(this.loopParent) && this.loopParent.label;
       this.loopPath = loopPath;
       this.loop = loopPath.node;
     }
@@ -360,11 +407,13 @@ class BlockScoping {
         // The same identifier might have been bound separately in the block scope and
         // the enclosing scope (e.g. loop or catch statement), so we should handle both
         // individually
-        if (scope.hasOwnBinding(key))
-          {scope.rename(ref.name);}
+        if (scope.hasOwnBinding(key)) {
+          scope.rename(ref.name);
+        }
 
-        if (this.blockPath.scope.hasOwnBinding(key))
-          {this.blockPath.scope.rename(ref.name);}
+        if (this.blockPath.scope.hasOwnBinding(key)) {
+          this.blockPath.scope.rename(ref.name);
+        }
       }
     }
   }
@@ -373,7 +422,7 @@ class BlockScoping {
     if (this.file.opts.throwIfClosureRequired) {
       throw this.blockPath.buildCodeFrameError(
         "Compiling let/const in this block would add a closure " +
-        "(throwIfClosureRequired)."
+          "(throwIfClosureRequired).",
       );
     }
     const block = this.block;
@@ -385,7 +434,10 @@ class BlockScoping {
       for (const name in outsideRefs) {
         const id = outsideRefs[name];
 
-        if (this.scope.hasGlobal(id.name) || this.scope.parentHasBinding(id.name)) {
+        if (
+          this.scope.hasGlobal(id.name) ||
+          this.scope.parentHasBinding(id.name)
+        ) {
           delete outsideRefs[id.name];
           delete this.letReferences[id.name];
 
@@ -411,8 +463,11 @@ class BlockScoping {
     const isSwitch = this.blockPath.isSwitchStatement();
 
     // build the closure that we're going to wrap the block with, possible wrapping switch(){}
-    const fn = t.functionExpression(null, params,
-      t.blockStatement(isSwitch ? [block] : block.body));
+    const fn = t.functionExpression(
+      null,
+      params,
+      t.blockStatement(isSwitch ? [block] : block.body),
+    );
 
     // continuation
     this.addContinuations(fn);
@@ -421,7 +476,12 @@ class BlockScoping {
     let basePath = ".callee";
 
     // handle generators
-    const hasYield = traverse.hasType(fn.body, this.scope, "YieldExpression", t.FUNCTION_TYPES);
+    const hasYield = traverse.hasType(
+      fn.body,
+      this.scope,
+      "YieldExpression",
+      t.FUNCTION_TYPES,
+    );
     if (hasYield) {
       fn.generator = true;
       call = t.yieldExpression(call, true);
@@ -429,7 +489,12 @@ class BlockScoping {
     }
 
     // handlers async functions
-    const hasAsync = traverse.hasType(fn.body, this.scope, "AwaitExpression", t.FUNCTION_TYPES);
+    const hasAsync = traverse.hasType(
+      fn.body,
+      this.scope,
+      "AwaitExpression",
+      t.FUNCTION_TYPES,
+    );
     if (hasAsync) {
       fn.async = true;
       call = t.awaitExpression(call);
@@ -441,9 +506,9 @@ class BlockScoping {
     if (this.has.hasReturn || this.has.hasBreakContinue) {
       const ret = this.scope.generateUidIdentifier("ret");
 
-      this.body.push(t.variableDeclaration("var", [
-        t.variableDeclarator(ret, call),
-      ]));
+      this.body.push(
+        t.variableDeclaration("var", [t.variableDeclarator(ret, call)]),
+      );
       placeholderPath = "declarations.0.init" + basePath;
       index = this.body.length - 1;
 
@@ -471,9 +536,9 @@ class BlockScoping {
     let fnPath;
     if (this.loop) {
       const ref = this.scope.generateUidIdentifier("loop");
-      const p = this.loopPath.insertBefore(t.variableDeclaration("var", [
-        t.variableDeclarator(ref, fn),
-      ]));
+      const p = this.loopPath.insertBefore(
+        t.variableDeclaration("var", [t.variableDeclarator(ref, fn)]),
+      );
 
       placeholder.replaceWith(ref);
       fnPath = p[0].get("declarations.0.init");
@@ -512,7 +577,9 @@ class BlockScoping {
       this.scope.rename(param.name, newParam.name, fn);
 
       // assign outer reference as it's been modified internally and needs to be retained
-      fn.body.body.push(t.expressionStatement(t.assignmentExpression("=", param, newParam)));
+      fn.body.body.push(
+        t.expressionStatement(t.assignmentExpression("=", param, newParam)),
+      );
     }
   }
 
@@ -531,7 +598,11 @@ class BlockScoping {
 
     const addDeclarationsFromChild = (path, node) => {
       node = node || path.node;
-      if (t.isClassDeclaration(node) || t.isFunctionDeclaration(node) || isBlockScoped(node)) {
+      if (
+        t.isClassDeclaration(node) ||
+        t.isFunctionDeclaration(node) ||
+        isBlockScoped(node)
+      ) {
         if (isBlockScoped(node)) {
           convertBlockScopedToVar(path, node, block, this.scope);
         }
@@ -585,7 +656,7 @@ class BlockScoping {
     };
 
     const loopOrFunctionParent = this.blockPath.find(
-      (path) => path.isLoop() || path.isFunction()
+      path => path.isLoop() || path.isFunction(),
     );
     if (loopOrFunctionParent && loopOrFunctionParent.isLoop()) {
       // There is a loop ancestor closer than the closest function, so we
@@ -686,18 +757,20 @@ class BlockScoping {
 
       if (cases.length === 1) {
         const single = cases[0];
-        body.push(t.ifStatement(
-          t.binaryExpression("===", ret, single.test),
-          single.consequent[0]
-        ));
+        body.push(
+          t.ifStatement(
+            t.binaryExpression("===", ret, single.test),
+            single.consequent[0],
+          ),
+        );
       } else {
         if (this.loop) {
           // https://github.com/babel/babel/issues/998
           for (let i = 0; i < cases.length; i++) {
             const caseConsequent = cases[i].consequent[0];
             if (t.isBreakStatement(caseConsequent) && !caseConsequent.label) {
-              caseConsequent.label = this.loopLabel = this.loopLabel ||
-                this.scope.generateUidIdentifier("loop");
+              caseConsequent.label = this.loopLabel =
+                this.loopLabel || this.scope.generateUidIdentifier("loop");
             }
           }
         }
diff --git a/packages/babel-plugin-transform-es2015-block-scoping/src/tdz.js b/packages/babel-plugin-transform-es2015-block-scoping/src/tdz.js
index 5b8d55796a..e9ec166e16 100644
--- a/packages/babel-plugin-transform-es2015-block-scoping/src/tdz.js
+++ b/packages/babel-plugin-transform-es2015-block-scoping/src/tdz.js
@@ -13,10 +13,11 @@ function getTDZStatus(refPath, bindingPath) {
 }
 
 function buildTDZAssert(node, file) {
-  return t.callExpression(
-    file.addHelper("temporalRef"),
-    [node, t.stringLiteral(node.name), file.addHelper("temporalUndefined")]
-  );
+  return t.callExpression(file.addHelper("temporalRef"), [
+    node,
+    t.stringLiteral(node.name),
+    file.addHelper("temporalUndefined"),
+  ]);
 }
 
 function isReference(node, scope, state) {
@@ -56,12 +57,18 @@ export const visitor = {
         path.replaceWith(assert);
       }
     } else if (status === "outside") {
-      path.replaceWith(t.throwStatement(t.inherits(
-        t.newExpression(t.identifier("ReferenceError"), [
-          t.stringLiteral(`${node.name} is not defined - temporal dead zone`),
-        ]),
-        node
-      )));
+      path.replaceWith(
+        t.throwStatement(
+          t.inherits(
+            t.newExpression(t.identifier("ReferenceError"), [
+              t.stringLiteral(
+                `${node.name} is not defined - temporal dead zone`,
+              ),
+            ]),
+            node,
+          ),
+        ),
+      );
     }
   },
 
diff --git a/packages/babel-plugin-transform-es2015-classes/src/index.js b/packages/babel-plugin-transform-es2015-classes/src/index.js
index 8089594177..52380986aa 100644
--- a/packages/babel-plugin-transform-es2015-classes/src/index.js
+++ b/packages/babel-plugin-transform-es2015-classes/src/index.js
@@ -2,7 +2,7 @@ import LooseTransformer from "./loose";
 import VanillaTransformer from "./vanilla";
 import nameFunction from "babel-helper-function-name";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   // todo: investigate traversal requeueing
   const VISITED = Symbol();
 
@@ -12,15 +12,17 @@ export default function ({ types: t }) {
         if (!path.get("declaration").isClassDeclaration()) return;
 
         const { node } = path;
-        const ref = node.declaration.id || path.scope.generateUidIdentifier("class");
+        const ref =
+          node.declaration.id || path.scope.generateUidIdentifier("class");
         node.declaration.id = ref;
 
         // Split the class declaration and the export into two separate statements.
         path.replaceWith(node.declaration);
-        path.insertAfter(t.exportNamedDeclaration(
-          null,
-          [t.exportSpecifier(ref, t.identifier("default"))]
-        ));
+        path.insertAfter(
+          t.exportNamedDeclaration(null, [
+            t.exportSpecifier(ref, t.identifier("default")),
+          ]),
+        );
       },
 
       ClassDeclaration(path) {
@@ -28,9 +30,11 @@ export default function ({ types: t }) {
 
         const ref = node.id || path.scope.generateUidIdentifier("class");
 
-        path.replaceWith(t.variableDeclaration("let", [
-          t.variableDeclarator(ref, t.toExpression(node)),
-        ]));
+        path.replaceWith(
+          t.variableDeclaration("let", [
+            t.variableDeclarator(ref, t.toExpression(node)),
+          ]),
+        );
       },
 
       ClassExpression(path, state) {
@@ -47,7 +51,10 @@ export default function ({ types: t }) {
 
         path.replaceWith(new Constructor(path, state.file).run());
 
-        if (path.isCallExpression() && path.get("callee").isArrowFunctionExpression()) {
+        if (
+          path.isCallExpression() &&
+          path.get("callee").isArrowFunctionExpression()
+        ) {
           path.get("callee").arrowFunctionToExpression();
         }
       },
diff --git a/packages/babel-plugin-transform-es2015-classes/src/lib/memoise-decorators.js b/packages/babel-plugin-transform-es2015-classes/src/lib/memoise-decorators.js
index 6583d081dc..6c9693ff63 100644
--- a/packages/babel-plugin-transform-es2015-classes/src/lib/memoise-decorators.js
+++ b/packages/babel-plugin-transform-es2015-classes/src/lib/memoise-decorators.js
@@ -1,7 +1,10 @@
 import type { Scope } from "babel-traverse";
 import * as t from "babel-types";
 
-export default function (decorators: Array<Object>, scope: Scope): Array<Object> {
+export default function(
+  decorators: Array<Object>,
+  scope: Scope,
+): Array<Object> {
   for (const decorator of decorators) {
     const expression = decorator.expression;
     if (!t.isMemberExpression(expression)) continue;
@@ -18,13 +21,15 @@ export default function (decorators: Array<Object>, scope: Scope): Array<Object>
       ref = expression.object;
     }
 
-    nodes.push(t.callExpression(
-      t.memberExpression(
-        t.memberExpression(ref, expression.property, expression.computed),
-        t.identifier("bind")
+    nodes.push(
+      t.callExpression(
+        t.memberExpression(
+          t.memberExpression(ref, expression.property, expression.computed),
+          t.identifier("bind"),
+        ),
+        [ref],
       ),
-      [ref]
-    ));
+    );
 
     if (nodes.length === 1) {
       decorator.expression = nodes[0];
diff --git a/packages/babel-plugin-transform-es2015-classes/src/loose.js b/packages/babel-plugin-transform-es2015-classes/src/loose.js
index 57f7abbbec..953a8a2322 100644
--- a/packages/babel-plugin-transform-es2015-classes/src/loose.js
+++ b/packages/babel-plugin-transform-es2015-classes/src/loose.js
@@ -13,10 +13,22 @@ export default class LooseClassTransformer extends VanillaTransformer {
       // use assignments instead of define properties for loose classes
 
       let classRef = this.classRef;
-      if (!node.static) classRef = t.memberExpression(classRef, t.identifier("prototype"));
-      const methodName = t.memberExpression(classRef, node.key, node.computed || t.isLiteral(node.key));
+      if (!node.static) {
+        classRef = t.memberExpression(classRef, t.identifier("prototype"));
+      }
+      const methodName = t.memberExpression(
+        classRef,
+        node.key,
+        node.computed || t.isLiteral(node.key),
+      );
 
-      let func = t.functionExpression(null, node.params, node.body, node.generator, node.async);
+      let func = t.functionExpression(
+        null,
+        node.params,
+        node.body,
+        node.generator,
+        node.async,
+      );
       func.returnType = node.returnType;
       const key = t.toComputedKey(node, node.key);
       if (t.isStringLiteral(key)) {
@@ -27,7 +39,9 @@ export default class LooseClassTransformer extends VanillaTransformer {
         });
       }
 
-      const expr = t.expressionStatement(t.assignmentExpression("=", methodName, func));
+      const expr = t.expressionStatement(
+        t.assignmentExpression("=", methodName, func),
+      );
       t.inheritsComments(expr, node);
       this.body.push(expr);
       return true;
diff --git a/packages/babel-plugin-transform-es2015-classes/src/vanilla.js b/packages/babel-plugin-transform-es2015-classes/src/vanilla.js
index 52e5153e91..81870b9b2c 100644
--- a/packages/babel-plugin-transform-es2015-classes/src/vanilla.js
+++ b/packages/babel-plugin-transform-es2015-classes/src/vanilla.js
@@ -22,47 +22,61 @@ const noMethodVisitor = {
   },
 };
 
-const verifyConstructorVisitor = visitors.merge([noMethodVisitor, {
-  MemberExpression: {
-    exit(path) {
-      const objectPath = path.get("object");
-      if (this.isDerived && !this.hasBareSuper && objectPath.isSuper()) {
-        const hasArrowFunctionParent = path.findParent((p) => p.isArrowFunctionExpression());
-        if (!hasArrowFunctionParent) {
-          throw objectPath.buildCodeFrameError("'super.*' is not allowed before super()");
+const verifyConstructorVisitor = visitors.merge([
+  noMethodVisitor,
+  {
+    MemberExpression: {
+      exit(path) {
+        const objectPath = path.get("object");
+        if (this.isDerived && !this.hasBareSuper && objectPath.isSuper()) {
+          const hasArrowFunctionParent = path.findParent(p =>
+            p.isArrowFunctionExpression(),
+          );
+          if (!hasArrowFunctionParent) {
+            throw objectPath.buildCodeFrameError(
+              "'super.*' is not allowed before super()",
+            );
+          }
+        }
+      },
+    },
+
+    CallExpression: {
+      exit(path) {
+        if (path.get("callee").isSuper()) {
+          this.hasBareSuper = true;
+
+          if (!this.isDerived) {
+            throw path.buildCodeFrameError(
+              "super() is only allowed in a derived constructor",
+            );
+          }
+        }
+      },
+    },
+
+    ThisExpression(path) {
+      if (this.isDerived && !this.hasBareSuper) {
+        const fn = path.find(p => p.isFunction());
+
+        if (!fn || !fn.isArrowFunctionExpression()) {
+          throw path.buildCodeFrameError(
+            "'this' is not allowed before super()",
+          );
         }
       }
     },
   },
+]);
 
-  CallExpression: {
-    exit(path) {
-      if (path.get("callee").isSuper()) {
-        this.hasBareSuper = true;
-
-        if (!this.isDerived) {
-          throw path.buildCodeFrameError("super() is only allowed in a derived constructor");
-        }
-      }
+const findThisesVisitor = visitors.merge([
+  noMethodVisitor,
+  {
+    ThisExpression(path) {
+      this.superThises.push(path);
     },
   },
-
-  ThisExpression(path) {
-    if (this.isDerived && !this.hasBareSuper) {
-      const fn = path.find((p) => p.isFunction());
-
-      if (!fn || !fn.isArrowFunctionExpression()) {
-        throw path.buildCodeFrameError("'this' is not allowed before super()");
-      }
-    }
-  },
-}]);
-
-const findThisesVisitor = visitors.merge([noMethodVisitor, {
-  ThisExpression(path) {
-    this.superThises.push(path);
-  },
-}]);
+]);
 
 export default class ClassTransformer {
   constructor(path: NodePath, file) {
@@ -92,8 +106,9 @@ export default class ClassTransformer {
     this.classId = this.node.id;
 
     // this is the name of the binding that will **always** reference the class we've constructed
-    this.classRef = this.node.id ? t.identifier(this.node.id.name) :
-      this.scope.generateUidIdentifier("class");
+    this.classRef = this.node.id
+      ? t.identifier(this.node.id.name)
+      : this.scope.generateUidIdentifier("class");
 
     this.superName = this.node.superClass || t.identifier("Function");
     this.isDerived = !!this.node.superClass;
@@ -106,7 +121,7 @@ export default class ClassTransformer {
 
     //
 
-    const constructorBody = this.constructorBody = t.blockStatement([]);
+    const constructorBody = (this.constructorBody = t.blockStatement([]));
     this.constructor = this.buildConstructor();
 
     //
@@ -129,15 +144,17 @@ export default class ClassTransformer {
 
     // make sure this class isn't directly called (with A() instead new A())
     if (!this.isLoose) {
-      constructorBody.body.unshift(t.expressionStatement(t.callExpression(
-        file.addHelper("classCallCheck"), [
-          t.thisExpression(),
-          this.classRef,
-        ]
-      )));
+      constructorBody.body.unshift(
+        t.expressionStatement(
+          t.callExpression(file.addHelper("classCallCheck"), [
+            t.thisExpression(),
+            this.classRef,
+          ]),
+        ),
+      );
     }
 
-    body = body.concat(this.staticPropBody.map((fn) => fn(this.classRef)));
+    body = body.concat(this.staticPropBody.map(fn => fn(this.classRef)));
 
     if (this.classId) {
       // named class with only a constructor
@@ -147,7 +164,10 @@ export default class ClassTransformer {
     //
     body.push(t.returnStatement(this.classRef));
 
-    const container = t.arrowFunctionExpression(closureParams, t.blockStatement(body));
+    const container = t.arrowFunctionExpression(
+      closureParams,
+      t.blockStatement(body),
+    );
     return t.callExpression(container, closureArgs);
   }
 
@@ -201,12 +221,12 @@ export default class ClassTransformer {
       body = t.blockStatement([]);
     }
 
-    this.path.get("body").unshiftContainer("body", t.classMethod(
-      "constructor",
-      t.identifier("constructor"),
-      params,
-      body
-    ));
+    this.path
+      .get("body")
+      .unshiftContainer(
+        "body",
+        t.classMethod("constructor", t.identifier("constructor"), params, body),
+      );
   }
 
   buildBody() {
@@ -216,7 +236,9 @@ export default class ClassTransformer {
 
     if (this.userConstructor) {
       const constructorBody = this.constructorBody;
-      constructorBody.body = constructorBody.body.concat(this.userConstructor.body.body);
+      constructorBody.body = constructorBody.body.concat(
+        this.userConstructor.body.body,
+      );
       t.inherits(this.constructor, this.userConstructor);
       t.inherits(constructorBody, this.userConstructor.body);
     }
@@ -236,7 +258,8 @@ export default class ClassTransformer {
 
       if (node.decorators) {
         throw path.buildCodeFrameError(
-          "Method has decorators, put the decorator plugin before the classes one.");
+          "Method has decorators, put the decorator plugin before the classes one.",
+        );
       }
 
       if (t.isClassMethod(node)) {
@@ -246,21 +269,26 @@ export default class ClassTransformer {
           path.traverse(verifyConstructorVisitor, this);
 
           if (!this.hasBareSuper && this.isDerived) {
-            throw path.buildCodeFrameError("missing super() call in constructor");
+            throw path.buildCodeFrameError(
+              "missing super() call in constructor",
+            );
           }
         }
 
-        const replaceSupers = new ReplaceSupers({
-          forceSuperMemoisation: isConstructor,
-          methodPath: path,
-          methodNode: node,
-          objectRef: this.classRef,
-          superRef: this.superName,
-          isStatic: node.static,
-          isLoose: this.isLoose,
-          scope: this.scope,
-          file: this.file,
-        }, true);
+        const replaceSupers = new ReplaceSupers(
+          {
+            forceSuperMemoisation: isConstructor,
+            methodPath: path,
+            methodNode: node,
+            objectRef: this.classRef,
+            superRef: this.superName,
+            isStatic: node.static,
+            isLoose: this.isLoose,
+            scope: this.scope,
+            file: this.file,
+          },
+          true,
+        );
 
         replaceSupers.replace();
 
@@ -298,8 +326,12 @@ export default class ClassTransformer {
     }
 
     if (instanceProps || staticProps) {
-      if (instanceProps) instanceProps = defineMap.toComputedObjectFromClass(instanceProps);
-      if (staticProps) staticProps = defineMap.toComputedObjectFromClass(staticProps);
+      if (instanceProps) {
+        instanceProps = defineMap.toComputedObjectFromClass(instanceProps);
+      }
+      if (staticProps) {
+        staticProps = defineMap.toComputedObjectFromClass(staticProps);
+      }
 
       const nullNode = t.nullLiteral();
 
@@ -330,10 +362,11 @@ export default class ClassTransformer {
       }
       args = args.slice(0, lastNonNullIndex + 1);
 
-
-      body.push(t.expressionStatement(
-        t.callExpression(this.file.addHelper("createClass"), args)
-      ));
+      body.push(
+        t.expressionStatement(
+          t.callExpression(this.file.addHelper("createClass"), args),
+        ),
+      );
     }
 
     this.clearDescriptors();
@@ -353,13 +386,21 @@ export default class ClassTransformer {
       if (
         bareSuperNode.arguments.length === 2 &&
         t.isSpreadElement(bareSuperNode.arguments[1]) &&
-        t.isIdentifier(bareSuperNode.arguments[1].argument, { name: "arguments" })
+        t.isIdentifier(bareSuperNode.arguments[1].argument, {
+          name: "arguments",
+        })
       ) {
         // special case single arguments spread
         bareSuperNode.arguments[1] = bareSuperNode.arguments[1].argument;
-        bareSuperNode.callee = t.memberExpression(superRef, t.identifier("apply"));
+        bareSuperNode.callee = t.memberExpression(
+          superRef,
+          t.identifier("apply"),
+        );
       } else {
-        bareSuperNode.callee = t.memberExpression(superRef, t.identifier("call"));
+        bareSuperNode.callee = t.memberExpression(
+          superRef,
+          t.identifier("call"),
+        );
       }
     } else {
       bareSuperNode = optimiseCall(
@@ -367,12 +408,15 @@ export default class ClassTransformer {
           "||",
           t.memberExpression(this.classRef, t.identifier("__proto__")),
           t.callExpression(
-            t.memberExpression(t.identifier("Object"), t.identifier("getPrototypeOf")),
-            [this.classRef]
-          )
+            t.memberExpression(
+              t.identifier("Object"),
+              t.identifier("getPrototypeOf"),
+            ),
+            [this.classRef],
+          ),
         ),
         t.thisExpression(),
-        bareSuperNode.arguments
+        bareSuperNode.arguments,
       );
     }
 
@@ -383,11 +427,11 @@ export default class ClassTransformer {
     } else {
       call = t.callExpression(
         this.file.addHelper("possibleConstructorReturn"),
-        [t.thisExpression(), bareSuperNode]
+        [t.thisExpression(), bareSuperNode],
       );
     }
 
-    const bareSuperAfter = this.bareSuperAfter.map((fn) => fn(thisRef));
+    const bareSuperAfter = this.bareSuperAfter.map(fn => fn(thisRef));
 
     if (
       bareSuper.parentPath.isExpressionStatement() &&
@@ -409,14 +453,11 @@ export default class ClassTransformer {
       bareSuper.parentPath.replaceWith(t.returnStatement(call));
     } else {
       bareSuper.replaceWithMultiple([
-        t.variableDeclaration("var", [
-          t.variableDeclarator(thisRef, call),
-        ]),
+        t.variableDeclaration("var", [t.variableDeclarator(thisRef, call)]),
         ...bareSuperAfter,
         t.expressionStatement(thisRef),
       ]);
     }
-
   }
 
   verifyConstructor() {
@@ -436,7 +477,7 @@ export default class ClassTransformer {
       this.wrapSuperCall(bareSuper, superRef, thisRef, body);
 
       if (guaranteedSuperBeforeFinish) {
-        bareSuper.find(function (parentPath) {
+        bareSuper.find(function(parentPath) {
           // hit top so short circuit
           if (parentPath === path) {
             return true;
@@ -457,31 +498,38 @@ export default class ClassTransformer {
     let wrapReturn;
 
     if (this.isLoose) {
-      wrapReturn = (returnArg) => {
-        return returnArg ? t.logicalExpression("||", returnArg, thisRef) : thisRef;
+      wrapReturn = returnArg => {
+        return returnArg
+          ? t.logicalExpression("||", returnArg, thisRef)
+          : thisRef;
       };
     } else {
-      wrapReturn = (returnArg) => t.callExpression(
-        this.file.addHelper("possibleConstructorReturn"),
-        [thisRef].concat(returnArg || [])
-      );
+      wrapReturn = returnArg =>
+        t.callExpression(
+          this.file.addHelper("possibleConstructorReturn"),
+          [thisRef].concat(returnArg || []),
+        );
     }
 
     // if we have a return as the last node in the body then we've already caught that
     // return
     const bodyPaths = body.get("body");
     if (bodyPaths.length && !bodyPaths.pop().isReturnStatement()) {
-      body.pushContainer("body", t.returnStatement(
-        guaranteedSuperBeforeFinish ? thisRef : wrapReturn()));
+      body.pushContainer(
+        "body",
+        t.returnStatement(guaranteedSuperBeforeFinish ? thisRef : wrapReturn()),
+      );
     }
 
     for (const returnPath of this.superReturns) {
       if (returnPath.node.argument) {
         const ref = returnPath.scope.generateDeclaredUidIdentifier("ret");
-        returnPath.get("argument").replaceWithMultiple([
-          t.assignmentExpression("=", ref, returnPath.node.argument),
-          wrapReturn(ref),
-        ]);
+        returnPath
+          .get("argument")
+          .replaceWithMultiple([
+            t.assignmentExpression("=", ref, returnPath.node.argument),
+            wrapReturn(ref),
+          ]);
       } else {
         returnPath.get("argument").replaceWith(wrapReturn());
       }
@@ -510,7 +558,11 @@ export default class ClassTransformer {
    * Replace the constructor body of our class.
    */
 
-  pushConstructor(replaceSupers, method: { type: "ClassMethod" }, path: NodePath) {
+  pushConstructor(
+    replaceSupers,
+    method: { type: "ClassMethod" },
+    path: NodePath,
+  ) {
     this.bareSupers = replaceSupers.bareSupers;
     this.superReturns = replaceSupers.returns;
 
@@ -561,9 +613,15 @@ export default class ClassTransformer {
     // Unshift to ensure that the constructor inheritance is set up before
     // any properties can be assigned to the prototype.
     this.pushedInherits = true;
-    this.body.unshift(t.expressionStatement(t.callExpression(
-      this.isLoose ? this.file.addHelper("inheritsLoose") : this.file.addHelper("inherits"),
-      [this.classRef, this.superName]
-    )));
+    this.body.unshift(
+      t.expressionStatement(
+        t.callExpression(
+          this.isLoose
+            ? this.file.addHelper("inheritsLoose")
+            : this.file.addHelper("inherits"),
+          [this.classRef, this.superName],
+        ),
+      ),
+    );
   }
 }
diff --git a/packages/babel-plugin-transform-es2015-computed-properties/src/index.js b/packages/babel-plugin-transform-es2015-computed-properties/src/index.js
index 87f2de6a33..7f51f88cd3 100644
--- a/packages/babel-plugin-transform-es2015-computed-properties/src/index.js
+++ b/packages/babel-plugin-transform-es2015-computed-properties/src/index.js
@@ -1,4 +1,4 @@
-export default function ({ types: t, template }) {
+export default function({ types: t, template }) {
   const buildMutatorMapAssign = template(`
     MUTATOR_MAP_REF[KEY] = MUTATOR_MAP_REF[KEY] || {};
     MUTATOR_MAP_REF[KEY].KIND = VALUE;
@@ -8,7 +8,13 @@ export default function ({ types: t, template }) {
     if (t.isObjectProperty(prop)) {
       return prop.value;
     } else if (t.isObjectMethod(prop)) {
-      return t.functionExpression(null, prop.params, prop.body, prop.generator, prop.async);
+      return t.functionExpression(
+        null,
+        prop.params,
+        prop.body,
+        prop.generator,
+        prop.async,
+      );
     }
   }
 
@@ -16,31 +22,44 @@ export default function ({ types: t, template }) {
     if (prop.kind === "get" && prop.kind === "set") {
       pushMutatorDefine(objId, prop, body);
     } else {
-      body.push(t.expressionStatement(
-        t.assignmentExpression(
-          "=",
-          t.memberExpression(objId, prop.key, prop.computed || t.isLiteral(prop.key)),
-          getValue(prop)
-        )
-      ));
+      body.push(
+        t.expressionStatement(
+          t.assignmentExpression(
+            "=",
+            t.memberExpression(
+              objId,
+              prop.key,
+              prop.computed || t.isLiteral(prop.key),
+            ),
+            getValue(prop),
+          ),
+        ),
+      );
     }
   }
 
   function pushMutatorDefine({ objId, body, getMutatorId, scope }, prop) {
-    let key = !prop.computed && t.isIdentifier(prop.key) ? t.stringLiteral(prop.key.name) : prop.key;
+    let key =
+      !prop.computed && t.isIdentifier(prop.key)
+        ? t.stringLiteral(prop.key.name)
+        : prop.key;
 
     const maybeMemoise = scope.maybeGenerateMemoised(key);
     if (maybeMemoise) {
-      body.push(t.expressionStatement(t.assignmentExpression("=", maybeMemoise, key)));
+      body.push(
+        t.expressionStatement(t.assignmentExpression("=", maybeMemoise, key)),
+      );
       key = maybeMemoise;
     }
 
-    body.push(...buildMutatorMapAssign({
-      MUTATOR_MAP_REF: getMutatorId(),
-      KEY: key,
-      VALUE: getValue(prop),
-      KIND: t.identifier(prop.kind),
-    }));
+    body.push(
+      ...buildMutatorMapAssign({
+        MUTATOR_MAP_REF: getMutatorId(),
+        KEY: key,
+        VALUE: getValue(prop),
+        KIND: t.identifier(prop.kind),
+      }),
+    );
   }
 
   function loose(info) {
@@ -71,13 +90,15 @@ export default function ({ types: t, template }) {
             getValue(prop),
           ]);
         } else {
-          body.push(t.expressionStatement(
-            t.callExpression(state.addHelper("defineProperty"), [
-              objId,
-              key,
-              getValue(prop),
-            ])
-          ));
+          body.push(
+            t.expressionStatement(
+              t.callExpression(state.addHelper("defineProperty"), [
+                objId,
+                key,
+                getValue(prop),
+              ]),
+            ),
+          );
         }
       }
     }
@@ -118,22 +139,26 @@ export default function ({ types: t, template }) {
           const initPropExpression = t.objectExpression(initProps);
           const body = [];
 
-          body.push(t.variableDeclaration("var", [
-            t.variableDeclarator(objId, initPropExpression),
-          ]));
+          body.push(
+            t.variableDeclaration("var", [
+              t.variableDeclarator(objId, initPropExpression),
+            ]),
+          );
 
           let callback = spec;
           if (state.opts.loose) callback = loose;
 
           let mutatorRef;
 
-          const getMutatorId = function () {
+          const getMutatorId = function() {
             if (!mutatorRef) {
               mutatorRef = scope.generateUidIdentifier("mutatorMap");
 
-              body.push(t.variableDeclaration("var", [
-                t.variableDeclarator(mutatorRef, t.objectExpression([])),
-              ]));
+              body.push(
+                t.variableDeclaration("var", [
+                  t.variableDeclarator(mutatorRef, t.objectExpression([])),
+                ]),
+              );
             }
 
             return mutatorRef;
@@ -150,10 +175,14 @@ export default function ({ types: t, template }) {
           });
 
           if (mutatorRef) {
-            body.push(t.expressionStatement(t.callExpression(
-              state.addHelper("defineEnumerableProperties"),
-              [objId, mutatorRef]
-            )));
+            body.push(
+              t.expressionStatement(
+                t.callExpression(
+                  state.addHelper("defineEnumerableProperties"),
+                  [objId, mutatorRef],
+                ),
+              ),
+            );
           }
 
           if (single) {
diff --git a/packages/babel-plugin-transform-es2015-destructuring/src/index.js b/packages/babel-plugin-transform-es2015-destructuring/src/index.js
index 733c32be2a..c2d970aa43 100644
--- a/packages/babel-plugin-transform-es2015-destructuring/src/index.js
+++ b/packages/babel-plugin-transform-es2015-destructuring/src/index.js
@@ -1,5 +1,4 @@
-export default function ({ types: t }) {
-
+export default function({ types: t }) {
   /**
    * Test if a VariableDeclaration's declarations contains any Patterns.
    */
@@ -86,7 +85,10 @@ export default function ({ types: t }) {
     }
 
     toArray(node, count) {
-      if (this.file.opts.loose || (t.isIdentifier(node) && this.arrays[node.name])) {
+      if (
+        this.file.opts.loose ||
+        (t.isIdentifier(node) && this.arrays[node.name])
+      ) {
         return node;
       } else {
         return this.scope.toArray(node, count);
@@ -97,7 +99,9 @@ export default function ({ types: t }) {
       // we need to assign the current value of the assignment to avoid evaluating
       // it more than once
 
-      const tempValueRef = this.scope.generateUidIdentifierBasedOnNode(valueRef);
+      const tempValueRef = this.scope.generateUidIdentifierBasedOnNode(
+        valueRef,
+      );
 
       const declar = t.variableDeclaration("var", [
         t.variableDeclarator(tempValueRef, valueRef),
@@ -110,13 +114,13 @@ export default function ({ types: t }) {
       const tempConditional = t.conditionalExpression(
         t.binaryExpression("===", tempValueRef, t.identifier("undefined")),
         pattern.right,
-        tempValueRef
+        tempValueRef,
       );
 
       const left = pattern.left;
       if (t.isPattern(left)) {
         const tempValueDefault = t.expressionStatement(
-          t.assignmentExpression("=", tempValueRef, tempConditional)
+          t.assignmentExpression("=", tempValueRef, tempConditional),
         );
         tempValueDefault._blockHoist = this.blockHoist;
 
@@ -143,7 +147,9 @@ export default function ({ types: t }) {
         if (t.isRestElement(prop)) continue;
 
         let key = prop.key;
-        if (t.isIdentifier(key) && !prop.computed) key = t.stringLiteral(prop.key.name);
+        if (t.isIdentifier(key) && !prop.computed) {
+          key = t.stringLiteral(prop.key.name);
+        }
         keys.push(key);
       }
 
@@ -152,7 +158,9 @@ export default function ({ types: t }) {
       //
 
       const value = t.callExpression(
-        this.file.addHelper("objectWithoutProperties"), [objRef, keys]);
+        this.file.addHelper("objectWithoutProperties"),
+        [objRef, keys],
+      );
       this.nodes.push(this.buildVariableAssignment(spreadProp.argument, value));
     }
 
@@ -173,9 +181,13 @@ export default function ({ types: t }) {
       // https://github.com/babel/babel/issues/681
 
       if (!pattern.properties.length) {
-        this.nodes.push(t.expressionStatement(
-          t.callExpression(this.file.addHelper("objectDestructuringEmpty"), [objRef])
-        ));
+        this.nodes.push(
+          t.expressionStatement(
+            t.callExpression(this.file.addHelper("objectDestructuringEmpty"), [
+              objRef,
+            ]),
+          ),
+        );
       }
 
       // if we have more than one properties in this pattern and the objectRef is a
@@ -207,7 +219,9 @@ export default function ({ types: t }) {
       // pattern has less elements than the array and doesn't have a rest so some
       // elements wont be evaluated
       if (pattern.elements.length > arr.elements.length) return;
-      if (pattern.elements.length < arr.elements.length && !hasRest(pattern)) return false;
+      if (pattern.elements.length < arr.elements.length && !hasRest(pattern)) {
+        return false;
+      }
 
       for (const elem of (pattern.elements: Array)) {
         // deopt on holes
@@ -293,8 +307,10 @@ export default function ({ types: t }) {
 
         if (t.isRestElement(elem)) {
           elemRef = this.toArray(arrayRef);
-          elemRef = t.callExpression(t.memberExpression(elemRef, t.identifier("slice")),
-            [t.numericLiteral(i)]);
+          elemRef = t.callExpression(
+            t.memberExpression(elemRef, t.identifier("slice")),
+            [t.numericLiteral(i)],
+          );
 
           // set the element to the rest element argument since we've dealt with it
           // being a rest already
@@ -327,7 +343,6 @@ export default function ({ types: t }) {
     }
   }
 
-
   return {
     visitor: {
       ExportNamedDeclaration(path) {
@@ -364,9 +379,9 @@ export default function ({ types: t }) {
 
           path.ensureBlock();
 
-          node.body.body.unshift(t.variableDeclaration("var", [
-            t.variableDeclarator(left, temp),
-          ]));
+          node.body.body.unshift(
+            t.variableDeclaration("var", [t.variableDeclarator(left, temp)]),
+          );
 
           return;
         }
@@ -432,12 +447,17 @@ export default function ({ types: t }) {
         });
 
         let ref;
-        if (path.isCompletionRecord() || !path.parentPath.isExpressionStatement()) {
+        if (
+          path.isCompletionRecord() ||
+          !path.parentPath.isExpressionStatement()
+        ) {
           ref = scope.generateUidIdentifierBasedOnNode(node.right, "ref");
 
-          nodes.push(t.variableDeclaration("var", [
-            t.variableDeclarator(ref, node.right),
-          ]));
+          nodes.push(
+            t.variableDeclaration("var", [
+              t.variableDeclarator(ref, node.right),
+            ]),
+          );
 
           if (t.isArrayExpression(node.right)) {
             destructuring.arrays[ref.name] = true;
@@ -486,15 +506,23 @@ export default function ({ types: t }) {
               t.inherits(nodes[nodes.length - 1], declar);
             }
           } else {
-            nodes.push(t.inherits(
-              destructuring.buildVariableAssignment(declar.id, declar.init), declar));
+            nodes.push(
+              t.inherits(
+                destructuring.buildVariableAssignment(declar.id, declar.init),
+                declar,
+              ),
+            );
           }
         }
 
         const nodesOut = [];
         for (const node of nodes) {
           const tail = nodesOut[nodesOut.length - 1];
-          if (tail && t.isVariableDeclaration(tail) && t.isVariableDeclaration(node)) {
+          if (
+            tail &&
+            t.isVariableDeclaration(tail) &&
+            t.isVariableDeclaration(node)
+          ) {
             // Create a single compound declarations
             tail.declarations.push(...node.declarations);
           } else {
diff --git a/packages/babel-plugin-transform-es2015-duplicate-keys/src/index.js b/packages/babel-plugin-transform-es2015-duplicate-keys/src/index.js
index 268af6e513..bb81c312e6 100644
--- a/packages/babel-plugin-transform-es2015-duplicate-keys/src/index.js
+++ b/packages/babel-plugin-transform-es2015-duplicate-keys/src/index.js
@@ -12,7 +12,9 @@ export default function() {
     visitor: {
       ObjectExpression(path) {
         const { node } = path;
-        const plainProps = node.properties.filter((prop) => !t.isSpreadElement(prop) && !prop.computed);
+        const plainProps = node.properties.filter(
+          prop => !t.isSpreadElement(prop) && !prop.computed,
+        );
 
         // A property is a duplicate key if:
         // * the property is a data property, and is preceeded by a data,
@@ -43,7 +45,11 @@ export default function() {
               alreadySeenSetters[name] = true;
               break;
             default:
-              if (alreadySeenData[name] || alreadySeenGetters[name] || alreadySeenSetters[name]) {
+              if (
+                alreadySeenData[name] ||
+                alreadySeenGetters[name] ||
+                alreadySeenSetters[name]
+              ) {
                 isDuplicate = true;
               }
               alreadySeenData[name] = true;
diff --git a/packages/babel-plugin-transform-es2015-for-of/src/index.js b/packages/babel-plugin-transform-es2015-for-of/src/index.js
index 1d2221a77d..a094171d71 100644
--- a/packages/babel-plugin-transform-es2015-for-of/src/index.js
+++ b/packages/babel-plugin-transform-es2015-for-of/src/index.js
@@ -1,4 +1,4 @@
-export default function ({ messages, template, types: t }) {
+export default function({ messages, template, types: t }) {
   const isArrayFrom = t.buildMatchMemberExpression("Array.from");
   const isObjectKeys = t.buildMatchMemberExpression("Object.keys");
   const isObjectValues = t.buildMatchMemberExpression("Object.values");
@@ -57,9 +57,9 @@ export default function ({ messages, template, types: t }) {
 
     if (!t.isIdentifier(right) || !scope.hasBinding(right.name)) {
       const uid = scope.generateUidIdentifier("arr");
-      nodes.push(t.variableDeclaration("var", [
-        t.variableDeclarator(uid, right),
-      ]));
+      nodes.push(
+        t.variableDeclaration("var", [t.variableDeclarator(uid, right)]),
+      );
       right = uid;
     }
 
@@ -81,8 +81,11 @@ export default function ({ messages, template, types: t }) {
       left.declarations[0].init = iterationValue;
       loop.body.body.unshift(left);
     } else {
-      loop.body.body.unshift(t.expressionStatement(
-        t.assignmentExpression("=", left, iterationValue)));
+      loop.body.body.unshift(
+        t.expressionStatement(
+          t.assignmentExpression("=", left, iterationValue),
+        ),
+      );
     }
 
     if (path.parentPath.isLabeledStatement()) {
@@ -111,19 +114,18 @@ export default function ({ messages, template, types: t }) {
     } else if (right.isIdentifier() && right.isPure()) {
       const binding = path.scope.getBinding(right.node.name);
       return optimize(path, binding.path.get("init"));
-    } else if (right.isCallExpression() && (
-      isArrayFrom(right.get("callee").node) ||
-      isObjectKeys(right.get("callee").node) ||
-      isObjectValues(right.get("callee").node) ||
-      isObjectEntries(right.get("callee").node)
-      )
+    } else if (
+      right.isCallExpression() &&
+      (isArrayFrom(right.get("callee").node) ||
+        isObjectKeys(right.get("callee").node) ||
+        isObjectValues(right.get("callee").node) ||
+        isObjectEntries(right.get("callee").node))
     ) {
-      const initPath = right === path.get("right") ? path : right.find((p) => p.isStatement());
+      const initPath =
+        right === path.get("right") ? path : right.find(p => p.isStatement());
       const uid = path.scope.generateUidIdentifierBasedOnNode(right.node);
       initPath.insertBefore(
-        t.variableDeclaration("const", [
-          t.variableDeclarator(uid, right.node),
-        ])
+        t.variableDeclaration("const", [t.variableDeclarator(uid, right.node)]),
       );
       right.replaceWith(uid);
       return replaceWithArray(path);
@@ -176,7 +178,11 @@ export default function ({ messages, template, types: t }) {
     const { left } = node;
     let declar, id;
 
-    if (t.isIdentifier(left) || t.isPattern(left) || t.isMemberExpression(left)) {
+    if (
+      t.isIdentifier(left) ||
+      t.isPattern(left) ||
+      t.isMemberExpression(left)
+    ) {
       // for (i of test), for ({ i } of test)
       id = left;
     } else if (t.isVariableDeclaration(left)) {
@@ -186,7 +192,10 @@ export default function ({ messages, template, types: t }) {
         t.variableDeclarator(left.declarations[0].id, id),
       ]);
     } else {
-      throw file.buildCodeFrameError(left, messages.get("unknownForHead", left.type));
+      throw file.buildCodeFrameError(
+        left,
+        messages.get("unknownForHead", left.type),
+      );
     }
 
     const iteratorKey = scope.generateUidIdentifier("iterator");
@@ -230,16 +239,25 @@ export default function ({ messages, template, types: t }) {
     const stepKey = scope.generateUidIdentifier("step");
     const stepValue = t.memberExpression(stepKey, t.identifier("value"));
 
-    if (t.isIdentifier(left) || t.isPattern(left) || t.isMemberExpression(left)) {
+    if (
+      t.isIdentifier(left) ||
+      t.isPattern(left) ||
+      t.isMemberExpression(left)
+    ) {
       // for (i of test), for ({ i } of test)
-      declar = t.expressionStatement(t.assignmentExpression("=", left, stepValue));
+      declar = t.expressionStatement(
+        t.assignmentExpression("=", left, stepValue),
+      );
     } else if (t.isVariableDeclaration(left)) {
       // for (let i of test)
       declar = t.variableDeclaration(left.kind, [
         t.variableDeclarator(left.declarations[0].id, stepValue),
       ]);
     } else {
-      throw file.buildCodeFrameError(left, messages.get("unknownForHead", left.type));
+      throw file.buildCodeFrameError(
+        left,
+        messages.get("unknownForHead", left.type),
+      );
     }
 
     //
@@ -248,7 +266,9 @@ export default function ({ messages, template, types: t }) {
 
     const template = buildForOf({
       ITERATOR_HAD_ERROR_KEY: scope.generateUidIdentifier("didIteratorError"),
-      ITERATOR_COMPLETION: scope.generateUidIdentifier("iteratorNormalCompletion"),
+      ITERATOR_COMPLETION: scope.generateUidIdentifier(
+        "iteratorNormalCompletion",
+      ),
       ITERATOR_ERROR_KEY: scope.generateUidIdentifier("iteratorError"),
       ITERATOR_KEY: iteratorKey,
       STEP_KEY: stepKey,
diff --git a/packages/babel-plugin-transform-es2015-function-name/src/index.js b/packages/babel-plugin-transform-es2015-function-name/src/index.js
index 737144c05a..7288694c4c 100644
--- a/packages/babel-plugin-transform-es2015-function-name/src/index.js
+++ b/packages/babel-plugin-transform-es2015-function-name/src/index.js
@@ -1,6 +1,6 @@
 import nameFunction from "babel-helper-function-name";
 
-export default function () {
+export default function() {
   return {
     visitor: {
       FunctionExpression: {
diff --git a/packages/babel-plugin-transform-es2015-instanceof/src/index.js b/packages/babel-plugin-transform-es2015-instanceof/src/index.js
index 50e10c06c4..f91c5eb4e0 100644
--- a/packages/babel-plugin-transform-es2015-instanceof/src/index.js
+++ b/packages/babel-plugin-transform-es2015-instanceof/src/index.js
@@ -1,10 +1,15 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   return {
     visitor: {
       BinaryExpression(path) {
         const { node } = path;
         if (node.operator === "instanceof") {
-          path.replaceWith(t.callExpression(this.addHelper("instanceof"), [node.left, node.right]));
+          path.replaceWith(
+            t.callExpression(this.addHelper("instanceof"), [
+              node.left,
+              node.right,
+            ]),
+          );
         }
       },
     },
diff --git a/packages/babel-plugin-transform-es2015-literals/src/index.js b/packages/babel-plugin-transform-es2015-literals/src/index.js
index 4e9dd463d2..2d3a30d03d 100644
--- a/packages/babel-plugin-transform-es2015-literals/src/index.js
+++ b/packages/babel-plugin-transform-es2015-literals/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     visitor: {
       NumericLiteral({ node }) {
diff --git a/packages/babel-plugin-transform-es2015-modules-amd/src/index.js b/packages/babel-plugin-transform-es2015-modules-amd/src/index.js
index 76db9c73ab..aaf1773048 100644
--- a/packages/babel-plugin-transform-es2015-modules-amd/src/index.js
+++ b/packages/babel-plugin-transform-es2015-modules-amd/src/index.js
@@ -12,7 +12,7 @@ const buildFactory = template(`
   })
 `);
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function isValidRequireCall(path) {
     if (!path.isCallExpression()) return false;
     if (!path.get("callee").isIdentifier({ name: "require" })) return false;
@@ -46,7 +46,7 @@ export default function ({ types: t }) {
       params.unshift(source[0]);
     }
 
-    return [ params, sources];
+    return [params, sources];
   }
 
   const amdVisitor = {
@@ -63,7 +63,9 @@ export default function ({ types: t }) {
     CallExpression(path) {
       if (!isValidRequireCall(path)) return;
       const source = path.node.arguments[0];
-      const ref = path.scope.generateUidIdentifier(basename(source.value, extname(source.value)));
+      const ref = path.scope.generateUidIdentifier(
+        basename(source.value, extname(source.value)),
+      );
       this.sources.push([ref, source, true]);
       path.remove();
     },
@@ -103,7 +105,7 @@ export default function ({ types: t }) {
 
           path.traverse(amdVisitor, this);
 
-          const [params, sources ] = buildParamsAndSource(this.sources);
+          const [params, sources] = buildParamsAndSource(this.sources);
 
           let moduleName = this.getModuleName();
           if (moduleName) moduleName = t.stringLiteral(moduleName);
@@ -126,11 +128,13 @@ export default function ({ types: t }) {
           factory.expression.body.directives = node.directives;
           node.directives = [];
 
-          node.body = [buildDefine({
-            MODULE_NAME: moduleName,
-            SOURCES: sources,
-            FACTORY: factory,
-          })];
+          node.body = [
+            buildDefine({
+              MODULE_NAME: moduleName,
+              SOURCES: sources,
+              FACTORY: factory,
+            }),
+          ];
         },
       },
     },
diff --git a/packages/babel-plugin-transform-es2015-modules-commonjs/src/index.js b/packages/babel-plugin-transform-es2015-modules-commonjs/src/index.js
index cc5130fc9a..f9746e4b37 100644
--- a/packages/babel-plugin-transform-es2015-modules-commonjs/src/index.js
+++ b/packages/babel-plugin-transform-es2015-modules-commonjs/src/index.js
@@ -42,10 +42,15 @@ const buildExportAll = template(`
   });
 `);
 
-const THIS_BREAK_KEYS = ["FunctionExpression", "FunctionDeclaration", "ClassProperty",
-  "ClassMethod", "ObjectMethod"];
+const THIS_BREAK_KEYS = [
+  "FunctionExpression",
+  "FunctionDeclaration",
+  "ClassProperty",
+  "ClassMethod",
+  "ObjectMethod",
+];
 
-export default function () {
+export default function() {
   const REASSIGN_REMAP_SKIP = Symbol();
 
   const reassignmentVisitor = {
@@ -61,8 +66,12 @@ export default function () {
         path.replaceWith(t.sequenceExpression([t.numericLiteral(0), remap]));
       } else if (path.isJSXIdentifier() && t.isMemberExpression(remap)) {
         const { object, property } = remap;
-        path.replaceWith(t.JSXMemberExpression(t.JSXIdentifier(object.name),
-          t.JSXIdentifier(property.name)));
+        path.replaceWith(
+          t.JSXMemberExpression(
+            t.JSXIdentifier(object.name),
+            t.JSXIdentifier(property.name),
+          ),
+        );
       } else {
         path.replaceWith(remap);
       }
@@ -104,9 +113,17 @@ export default function () {
       // redeclared in this scope
       if (this.scope.getBinding(name) !== path.scope.getBinding(name)) return;
 
-      const node = t.assignmentExpression(path.node.operator[0] + "=", arg.node, t.numericLiteral(1));
+      const node = t.assignmentExpression(
+        path.node.operator[0] + "=",
+        arg.node,
+        t.numericLiteral(1),
+      );
 
-      if ((path.parentPath.isExpressionStatement() && !path.isCompletionRecord()) || path.node.prefix) {
+      if (
+        (path.parentPath.isExpressionStatement() &&
+          !path.isCompletionRecord()) ||
+        path.node.prefix
+      ) {
         path.replaceWith(node);
         this.requeueInParent(path);
         return;
@@ -118,7 +135,8 @@ export default function () {
       let operator;
       if (path.node.operator === "--") {
         operator = "+";
-      } else { // "++"
+      } else {
+        // "++"
         operator = "-";
       }
       nodes.push(t.binaryExpression(operator, arg.node, t.numericLiteral(1)));
@@ -139,7 +157,7 @@ export default function () {
 
         if (
           state.opts.allowTopLevelThis !== true &&
-          !path.findParent((path) => THIS_BREAK_KEYS.indexOf(path.type) >= 0)
+          !path.findParent(path => THIS_BREAK_KEYS.indexOf(path.type) >= 0)
         ) {
           path.replaceWith(t.identifier("undefined"));
         }
@@ -177,12 +195,15 @@ export default function () {
             const cached = requires[source];
             if (cached) return cached;
 
-            const ref = path.scope.generateUidIdentifier(basename(source, extname(source)));
+            const ref = path.scope.generateUidIdentifier(
+              basename(source, extname(source)),
+            );
 
             const varDecl = t.variableDeclaration("var", [
-              t.variableDeclarator(ref, buildRequire(
-                t.stringLiteral(source)
-              ).expression),
+              t.variableDeclarator(
+                ref,
+                buildRequire(t.stringLiteral(source)).expression,
+              ),
             ]);
 
             // Copy location from the original import statement for sourcemap
@@ -197,7 +218,7 @@ export default function () {
 
             topNodes.push(varDecl);
 
-            return requires[source] = ref;
+            return (requires[source] = ref);
           }
 
           function addTo(obj, key, arr) {
@@ -209,11 +230,16 @@ export default function () {
             if (path.isExportDeclaration()) {
               hasExports = true;
 
-              const specifiers = [].concat(path.get("declaration"), path.get("specifiers"));
+              const specifiers = [].concat(
+                path.get("declaration"),
+                path.get("specifiers"),
+              );
               for (const specifier of specifiers) {
                 const ids = specifier.getBindingIdentifiers();
                 if (ids.__esModule) {
-                  throw specifier.buildCodeFrameError("Illegal export \"__esModule\"");
+                  throw specifier.buildCodeFrameError(
+                    'Illegal export "__esModule"',
+                  );
                 }
               }
             }
@@ -233,7 +259,7 @@ export default function () {
               if (typeof path.node._blockHoist === "number") {
                 importsEntry.maxBlockHoist = Math.max(
                   path.node._blockHoist,
-                  importsEntry.maxBlockHoist
+                  importsEntry.maxBlockHoist,
                 );
               }
 
@@ -250,7 +276,12 @@ export default function () {
                   topNodes.push(buildExportsAssignment(defNode, id));
                   path.replaceWith(declaration.node);
                 } else {
-                  topNodes.push(buildExportsAssignment(defNode, t.toExpression(declaration.node)));
+                  topNodes.push(
+                    buildExportsAssignment(
+                      defNode,
+                      t.toExpression(declaration.node),
+                    ),
+                  );
                   path.remove();
                 }
               } else if (declaration.isClassDeclaration()) {
@@ -263,7 +294,12 @@ export default function () {
                     buildExportsAssignment(defNode, id),
                   ]);
                 } else {
-                  path.replaceWith(buildExportsAssignment(defNode, t.toExpression(declaration.node)));
+                  path.replaceWith(
+                    buildExportsAssignment(
+                      defNode,
+                      t.toExpression(declaration.node),
+                    ),
+                  );
 
                   // Manualy re-queue `export default class {}` expressions so that the ES3 transform
                   // has an opportunity to convert them. Ideally this would happen automatically from the
@@ -271,7 +307,12 @@ export default function () {
                   path.parentPath.requeue(path.get("expression.left"));
                 }
               } else {
-                path.replaceWith(buildExportsAssignment(t.identifier("default"), declaration.node));
+                path.replaceWith(
+                  buildExportsAssignment(
+                    t.identifier("default"),
+                    declaration.node,
+                  ),
+                );
 
                 // Manualy re-queue `export default foo;` expressions so that the ES3 transform
                 // has an opportunity to convert them. Ideally this would happen automatically from the
@@ -306,7 +347,9 @@ export default function () {
 
                     if (id.isIdentifier()) {
                       addTo(exports, id.node.name, id.node);
-                      init.replaceWith(buildExportsAssignment(id.node, init.node).expression);
+                      init.replaceWith(
+                        buildExportsAssignment(id.node, init.node).expression,
+                      );
                       nonHoistedExportNames[id.node.name] = true;
                     } else if (id.isObjectPattern()) {
                       for (let i = 0; i < id.node.properties.length; i++) {
@@ -318,7 +361,9 @@ export default function () {
                           propValue = prop.argument;
                         }
                         addTo(exports, propValue.name, propValue);
-                        exportsToInsert.push(buildExportsAssignment(propValue, propValue));
+                        exportsToInsert.push(
+                          buildExportsAssignment(propValue, propValue),
+                        );
                         nonHoistedExportNames[propValue.name] = true;
                       }
                     } else if (id.isArrayPattern() && id.node.elements) {
@@ -332,7 +377,9 @@ export default function () {
                         }
                         const name = elem.name;
                         addTo(exports, name, elem);
-                        exportsToInsert.push(buildExportsAssignment(elem, elem));
+                        exportsToInsert.push(
+                          buildExportsAssignment(elem, elem),
+                        );
                         nonHoistedExportNames[name] = true;
                       }
                     }
@@ -356,15 +403,25 @@ export default function () {
                     // todo
                   } else if (specifier.isExportSpecifier()) {
                     if (!noInterop && specifier.node.local.name === "default") {
-                      topNodes.push(buildExportsFrom(t.stringLiteral(specifier.node.exported.name),
-                        t.memberExpression(
-                          t.callExpression(this.addHelper("interopRequireDefault"), [ref]),
-                          specifier.node.local
-                        )
-                      ));
+                      topNodes.push(
+                        buildExportsFrom(
+                          t.stringLiteral(specifier.node.exported.name),
+                          t.memberExpression(
+                            t.callExpression(
+                              this.addHelper("interopRequireDefault"),
+                              [ref],
+                            ),
+                            specifier.node.local,
+                          ),
+                        ),
+                      );
                     } else {
-                      topNodes.push(buildExportsFrom(t.stringLiteral(specifier.node.exported.name),
-                        t.memberExpression(ref, specifier.node.local)));
+                      topNodes.push(
+                        buildExportsFrom(
+                          t.stringLiteral(specifier.node.exported.name),
+                          t.memberExpression(ref, specifier.node.local),
+                        ),
+                      );
                     }
                     nonHoistedExportNames[specifier.node.exported.name] = true;
                   }
@@ -372,16 +429,28 @@ export default function () {
               } else {
                 for (const specifier of specifiers) {
                   if (specifier.isExportSpecifier()) {
-                    addTo(exports, specifier.node.local.name, specifier.node.exported);
+                    addTo(
+                      exports,
+                      specifier.node.local.name,
+                      specifier.node.exported,
+                    );
                     nonHoistedExportNames[specifier.node.exported.name] = true;
-                    nodes.push(buildExportsAssignment(specifier.node.exported, specifier.node.local));
+                    nodes.push(
+                      buildExportsAssignment(
+                        specifier.node.exported,
+                        specifier.node.local,
+                      ),
+                    );
                   }
                 }
               }
               path.replaceWithMultiple(nodes);
             } else if (path.isExportAllDeclaration()) {
               const exportNode = buildExportAll({
-                OBJECT: addRequire(path.node.source.value, path.node._blockHoist),
+                OBJECT: addRequire(
+                  path.node.source.value,
+                  path.node._blockHoist,
+                ),
               });
               exportNode.loc = path.node.loc;
               topNodes.push(exportNode);
@@ -407,8 +476,8 @@ export default function () {
                         specifier.local,
                         t.callExpression(
                           this.addHelper("interopRequireWildcard"),
-                          [uid]
-                        )
+                          [uid],
+                        ),
                       ),
                     ]);
 
@@ -420,7 +489,10 @@ export default function () {
                   }
                   wildcard = specifier.local;
                 } else if (t.isImportDefaultSpecifier(specifier)) {
-                  specifiers[i] = t.importSpecifier(specifier.local, t.identifier("default"));
+                  specifiers[i] = t.importSpecifier(
+                    specifier.local,
+                    t.identifier("default"),
+                  );
                 }
               }
 
@@ -431,14 +503,16 @@ export default function () {
                     if (wildcard) {
                       target = wildcard;
                     } else if (!noInterop) {
-                      target = wildcard = path.scope.generateUidIdentifier(uid.name);
+                      target = wildcard = path.scope.generateUidIdentifier(
+                        uid.name,
+                      );
                       const varDecl = t.variableDeclaration("var", [
                         t.variableDeclarator(
                           target,
                           t.callExpression(
                             this.addHelper("interopRequireDefault"),
-                            [uid]
-                          )
+                            [uid],
+                          ),
                         ),
                       ]);
 
@@ -449,8 +523,10 @@ export default function () {
                       topNodes.push(varDecl);
                     }
                   }
-                  remaps[specifier.local.name] = t.memberExpression(target,
-                    t.cloneWithoutLoc(specifier.imported));
+                  remaps[specifier.local.name] = t.memberExpression(
+                    target,
+                    t.cloneWithoutLoc(specifier.imported),
+                  );
                 }
               }
             } else {
@@ -462,25 +538,29 @@ export default function () {
           }
 
           if (hasImports && Object.keys(nonHoistedExportNames).length) {
-
             // avoid creating too long of export assignment to prevent stack overflow
             const maxHoistedExportsNodeAssignmentLength = 100;
             const nonHoistedExportNamesArr = Object.keys(nonHoistedExportNames);
 
             for (
               let currentExportsNodeAssignmentLength = 0;
-              currentExportsNodeAssignmentLength < nonHoistedExportNamesArr.length;
+              currentExportsNodeAssignmentLength <
+              nonHoistedExportNamesArr.length;
               currentExportsNodeAssignmentLength += maxHoistedExportsNodeAssignmentLength
             ) {
               const nonHoistedExportNamesChunk = nonHoistedExportNamesArr.slice(
                 currentExportsNodeAssignmentLength,
-                currentExportsNodeAssignmentLength + maxHoistedExportsNodeAssignmentLength);
+                currentExportsNodeAssignmentLength +
+                  maxHoistedExportsNodeAssignmentLength,
+              );
 
               let hoistedExportsNode = t.identifier("undefined");
 
-              nonHoistedExportNamesChunk.forEach(function (name) {
-                hoistedExportsNode = buildExportsAssignment(t.identifier(name), hoistedExportsNode)
-                  .expression;
+              nonHoistedExportNamesChunk.forEach(function(name) {
+                hoistedExportsNode = buildExportsAssignment(
+                  t.identifier(name),
+                  hoistedExportsNode,
+                ).expression;
               });
 
               const node = t.expressionStatement(hoistedExportsNode);
@@ -493,7 +573,9 @@ export default function () {
           // add __esModule declaration if this file has any exports
           if (hasExports && !strict) {
             let buildTemplate = buildExportsModuleDeclaration;
-            if (this.opts.loose) buildTemplate = buildLooseExportsModuleDeclaration;
+            if (this.opts.loose) {
+              buildTemplate = buildLooseExportsModuleDeclaration;
+            }
 
             const declar = buildTemplate();
             declar._blockHoist = 3;
@@ -506,7 +588,7 @@ export default function () {
             remaps,
             scope,
             exports,
-            requeueInParent: (newPath) => path.requeue(newPath),
+            requeueInParent: newPath => path.requeue(newPath),
           });
         },
       },
diff --git a/packages/babel-plugin-transform-es2015-modules-commonjs/test/esmodule-flag.js b/packages/babel-plugin-transform-es2015-modules-commonjs/test/esmodule-flag.js
index 6315e0d83a..52072fa43a 100644
--- a/packages/babel-plugin-transform-es2015-modules-commonjs/test/esmodule-flag.js
+++ b/packages/babel-plugin-transform-es2015-modules-commonjs/test/esmodule-flag.js
@@ -2,8 +2,8 @@ const assert = require("assert");
 const babel = require("babel-core");
 const vm = require("vm");
 
-test("Re-export doesn't overwrite __esModule flag", function () {
-  let code = "export * from \"./dep\";";
+test("Re-export doesn't overwrite __esModule flag", function() {
+  let code = 'export * from "./dep";';
   const depStub = {
     __esModule: false,
   };
@@ -12,7 +12,7 @@ test("Re-export doesn't overwrite __esModule flag", function () {
     module: {
       exports: {},
     },
-    require: function (id) {
+    require: function(id) {
       if (id === "./dep") return depStub;
       return require(id);
     },
@@ -20,10 +20,8 @@ test("Re-export doesn't overwrite __esModule flag", function () {
   context.exports = context.module.exports;
 
   code = babel.transform(code, {
-    "plugins": [
-      [require("../"), { loose: true }],
-    ],
-    "ast": false,
+    plugins: [[require("../"), { loose: true }]],
+    ast: false,
   }).code;
 
   vm.runInNewContext(code, context);
@@ -32,6 +30,6 @@ test("Re-export doesn't overwrite __esModule flag", function () {
   assert.equal(
     context.exports.__esModule,
     true,
-    "Expected exports.__esModule === true"
+    "Expected exports.__esModule === true",
   );
 });
diff --git a/packages/babel-plugin-transform-es2015-modules-systemjs/src/index.js b/packages/babel-plugin-transform-es2015-modules-systemjs/src/index.js
index 10383b609a..9b04dfff3b 100644
--- a/packages/babel-plugin-transform-es2015-modules-systemjs/src/index.js
+++ b/packages/babel-plugin-transform-es2015-modules-systemjs/src/index.js
@@ -20,10 +20,9 @@ const buildExportAll = template(`
   }
 `);
 
-
 const TYPE_IMPORT = "Import";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   const IGNORE_REASSIGNMENT_SYMBOL = Symbol();
 
   const reassignmentVisitor = {
@@ -49,20 +48,22 @@ export default function ({ types: t }) {
       // in order to ensure the same update expression value
       let isPostUpdateExpression = path.isUpdateExpression() && !node.prefix;
       if (isPostUpdateExpression) {
-        if (node.operator === "++")
-          {node = t.binaryExpression("+", node.argument, t.numericLiteral(1));}
-        else if (node.operator === "--")
-          {node = t.binaryExpression("-", node.argument, t.numericLiteral(1));}
-        else
-          {isPostUpdateExpression = false;}
+        if (node.operator === "++") {
+          node = t.binaryExpression("+", node.argument, t.numericLiteral(1));
+        } else if (node.operator === "--") {
+          node = t.binaryExpression("-", node.argument, t.numericLiteral(1));
+        } else {
+          isPostUpdateExpression = false;
+        }
       }
 
       for (const exportedName of exportedNames) {
         node = this.buildCall(exportedName, node).expression;
       }
 
-      if (isPostUpdateExpression)
-        {node = t.sequenceExpression([node, path.node]);}
+      if (isPostUpdateExpression) {
+        node = t.sequenceExpression([node, path.node]);
+      }
 
       path.replaceWith(node);
     },
@@ -70,18 +71,26 @@ export default function ({ types: t }) {
 
   return {
     visitor: {
-
       CallExpression(path, state) {
         if (path.node.callee.type === TYPE_IMPORT) {
           const contextIdent = state.contextIdent;
-          path.replaceWith(t.callExpression(t.memberExpression(contextIdent, t.identifier("import")),
-            path.node.arguments));
+          path.replaceWith(
+            t.callExpression(
+              t.memberExpression(contextIdent, t.identifier("import")),
+              path.node.arguments,
+            ),
+          );
         }
       },
 
       ReferencedIdentifier(path, state) {
-        if (path.node.name == "__moduleName" && !path.scope.hasBinding("__moduleName")) {
-          path.replaceWith(t.memberExpression(state.contextIdent, t.identifier("id")));
+        if (
+          path.node.name == "__moduleName" &&
+          !path.scope.hasBinding("__moduleName")
+        ) {
+          path.replaceWith(
+            t.memberExpression(state.contextIdent, t.identifier("id")),
+          );
         }
       },
 
@@ -109,20 +118,22 @@ export default function ({ types: t }) {
 
           function pushModule(source, key, specifiers) {
             let module;
-            modules.forEach(function (m) {
+            modules.forEach(function(m) {
               if (m.key === source) {
                 module = m;
               }
             });
             if (!module) {
-              modules.push(module = { key: source, imports: [], exports: [] });
+              modules.push(
+                (module = { key: source, imports: [], exports: [] }),
+              );
             }
             module[key] = module[key].concat(specifiers);
           }
 
           function buildExportCall(name, val) {
             return t.expressionStatement(
-              t.callExpression(exportIdent, [t.stringLiteral(name), val])
+              t.callExpression(exportIdent, [t.stringLiteral(name), val]),
             );
           }
 
@@ -154,7 +165,10 @@ export default function ({ types: t }) {
               path.remove();
             } else if (path.isExportDefaultDeclaration()) {
               const declar = path.get("declaration");
-              if (declar.isClassDeclaration() || declar.isFunctionDeclaration()) {
+              if (
+                declar.isClassDeclaration() ||
+                declar.isFunctionDeclaration()
+              ) {
                 const id = declar.node.id;
                 const nodes = [];
 
@@ -163,7 +177,9 @@ export default function ({ types: t }) {
                   nodes.push(buildExportCall("default", id));
                   addExportName(id.name, "default");
                 } else {
-                  nodes.push(buildExportCall("default", t.toExpression(declar.node)));
+                  nodes.push(
+                    buildExportCall("default", t.toExpression(declar.node)),
+                  );
                 }
 
                 if (!canHoist || declar.isClassDeclaration()) {
@@ -212,8 +228,16 @@ export default function ({ types: t }) {
                     const nodes = [];
 
                     for (const specifier of specifiers) {
-                      nodes.push(buildExportCall(specifier.exported.name, specifier.local));
-                      addExportName(specifier.local.name, specifier.exported.name);
+                      nodes.push(
+                        buildExportCall(
+                          specifier.exported.name,
+                          specifier.local,
+                        ),
+                      );
+                      addExportName(
+                        specifier.local.name,
+                        specifier.exported.name,
+                      );
                     }
 
                     path.replaceWithMultiple(nodes);
@@ -223,65 +247,103 @@ export default function ({ types: t }) {
             }
           }
 
-          modules.forEach(function (specifiers) {
+          modules.forEach(function(specifiers) {
             const setterBody = [];
             const target = path.scope.generateUidIdentifier(specifiers.key);
 
             for (let specifier of specifiers.imports) {
               if (t.isImportNamespaceSpecifier(specifier)) {
-                setterBody.push(t.expressionStatement(t.assignmentExpression("=", specifier.local, target)));
+                setterBody.push(
+                  t.expressionStatement(
+                    t.assignmentExpression("=", specifier.local, target),
+                  ),
+                );
               } else if (t.isImportDefaultSpecifier(specifier)) {
-                specifier = t.importSpecifier(specifier.local, t.identifier("default"));
+                specifier = t.importSpecifier(
+                  specifier.local,
+                  t.identifier("default"),
+                );
               }
 
               if (t.isImportSpecifier(specifier)) {
-                setterBody.push(t.expressionStatement(t.assignmentExpression("=", specifier.local,
-                  t.memberExpression(target, specifier.imported))));
+                setterBody.push(
+                  t.expressionStatement(
+                    t.assignmentExpression(
+                      "=",
+                      specifier.local,
+                      t.memberExpression(target, specifier.imported),
+                    ),
+                  ),
+                );
               }
             }
 
             if (specifiers.exports.length) {
-              const exportObjRef = path.scope.generateUidIdentifier("exportObj");
+              const exportObjRef = path.scope.generateUidIdentifier(
+                "exportObj",
+              );
 
-              setterBody.push(t.variableDeclaration("var", [
-                t.variableDeclarator(exportObjRef, t.objectExpression([])),
-              ]));
+              setterBody.push(
+                t.variableDeclaration("var", [
+                  t.variableDeclarator(exportObjRef, t.objectExpression([])),
+                ]),
+              );
 
               for (const node of specifiers.exports) {
                 if (t.isExportAllDeclaration(node)) {
-                  setterBody.push(buildExportAll({
-                    KEY: path.scope.generateUidIdentifier("key"),
-                    EXPORT_OBJ: exportObjRef,
-                    TARGET: target,
-                  }));
+                  setterBody.push(
+                    buildExportAll({
+                      KEY: path.scope.generateUidIdentifier("key"),
+                      EXPORT_OBJ: exportObjRef,
+                      TARGET: target,
+                    }),
+                  );
                 } else if (t.isExportSpecifier(node)) {
-                  setterBody.push(t.expressionStatement(
-                    t.assignmentExpression("=", t.memberExpression(exportObjRef, node.exported),
-                      t.memberExpression(target, node.local))
-                  ));
+                  setterBody.push(
+                    t.expressionStatement(
+                      t.assignmentExpression(
+                        "=",
+                        t.memberExpression(exportObjRef, node.exported),
+                        t.memberExpression(target, node.local),
+                      ),
+                    ),
+                  );
                 } else {
                   // todo
                 }
               }
 
-              setterBody.push(t.expressionStatement(t.callExpression(exportIdent, [exportObjRef])));
+              setterBody.push(
+                t.expressionStatement(
+                  t.callExpression(exportIdent, [exportObjRef]),
+                ),
+              );
             }
 
             sources.push(t.stringLiteral(specifiers.key));
-            setters.push(t.functionExpression(null, [target], t.blockStatement(setterBody)));
+            setters.push(
+              t.functionExpression(
+                null,
+                [target],
+                t.blockStatement(setterBody),
+              ),
+            );
           });
 
-
           let moduleName = this.getModuleName();
           if (moduleName) moduleName = t.stringLiteral(moduleName);
 
           if (canHoist) {
-            hoistVariables(path, (id) => variableIds.push(id));
+            hoistVariables(path, id => variableIds.push(id));
           }
 
           if (variableIds.length) {
-            beforeBody.unshift(t.variableDeclaration("var",
-              variableIds.map((id) => t.variableDeclarator(id))));
+            beforeBody.unshift(
+              t.variableDeclaration(
+                "var",
+                variableIds.map(id => t.variableDeclarator(id)),
+              ),
+            );
           }
 
           path.traverse(reassignmentVisitor, {
@@ -297,7 +359,9 @@ export default function ({ types: t }) {
           path.node.body = [
             buildTemplate({
               SYSTEM_REGISTER: t.memberExpression(
-                t.identifier(state.opts.systemGlobal || "System"), t.identifier("register")),
+                t.identifier(state.opts.systemGlobal || "System"),
+                t.identifier("register"),
+              ),
               BEFORE_BODY: beforeBody,
               MODULE_NAME: moduleName,
               SETTERS: setters,
diff --git a/packages/babel-plugin-transform-es2015-modules-umd/src/index.js b/packages/babel-plugin-transform-es2015-modules-umd/src/index.js
index 072275ed7d..2caaa2890d 100644
--- a/packages/babel-plugin-transform-es2015-modules-umd/src/index.js
+++ b/packages/babel-plugin-transform-es2015-modules-umd/src/index.js
@@ -25,7 +25,7 @@ const buildWrapper = template(`
   })(this, FUNC);
 `);
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function isValidDefine(path) {
     if (!path.isExpressionStatement()) return;
 
@@ -59,7 +59,7 @@ export default function ({ types: t }) {
           const func = call.arguments[1];
           const browserGlobals = state.opts.globals || {};
 
-          const commonArgs = amdArgs.elements.map((arg) => {
+          const commonArgs = amdArgs.elements.map(arg => {
             if (arg.value === "module" || arg.value === "exports") {
               return t.identifier(arg.value);
             } else {
@@ -67,30 +67,39 @@ export default function ({ types: t }) {
             }
           });
 
-          const browserArgs = amdArgs.elements.map((arg) => {
+          const browserArgs = amdArgs.elements.map(arg => {
             if (arg.value === "module") {
               return t.identifier("mod");
             } else if (arg.value === "exports") {
-              return t.memberExpression(t.identifier("mod"), t.identifier("exports"));
+              return t.memberExpression(
+                t.identifier("mod"),
+                t.identifier("exports"),
+              );
             } else {
               let memberExpression;
 
               if (state.opts.exactGlobals) {
                 const globalRef = browserGlobals[arg.value];
                 if (globalRef) {
-                  memberExpression = globalRef.split(".").reduce(
-                    (accum, curr) => t.memberExpression(accum, t.identifier(curr)), t.identifier("global")
-                  );
+                  memberExpression = globalRef
+                    .split(".")
+                    .reduce(
+                      (accum, curr) =>
+                        t.memberExpression(accum, t.identifier(curr)),
+                      t.identifier("global"),
+                    );
                 } else {
                   memberExpression = t.memberExpression(
-                    t.identifier("global"), t.identifier(t.toIdentifier(arg.value))
+                    t.identifier("global"),
+                    t.identifier(t.toIdentifier(arg.value)),
                   );
                 }
               } else {
                 const requireName = basename(arg.value, extname(arg.value));
                 const globalName = browserGlobals[requireName] || requireName;
                 memberExpression = t.memberExpression(
-                  t.identifier("global"), t.identifier(t.toIdentifier(globalName))
+                  t.identifier("global"),
+                  t.identifier(t.toIdentifier(globalName)),
                 );
               }
 
@@ -98,10 +107,15 @@ export default function ({ types: t }) {
             }
           });
 
-          const moduleNameOrBasename = moduleName ? moduleName.value :
-            basename(this.file.opts.filename, extname(this.file.opts.filename));
+          const moduleNameOrBasename = moduleName
+            ? moduleName.value
+            : basename(
+                this.file.opts.filename,
+                extname(this.file.opts.filename),
+              );
           let globalToAssign = t.memberExpression(
-            t.identifier("global"), t.identifier(t.toIdentifier(moduleNameOrBasename))
+            t.identifier("global"),
+            t.identifier(t.toIdentifier(moduleNameOrBasename)),
           );
           let prerequisiteAssignments = null;
 
@@ -113,7 +127,9 @@ export default function ({ types: t }) {
 
               const members = globalName.split(".");
               globalToAssign = members.slice(1).reduce((accum, curr) => {
-                prerequisiteAssignments.push(buildPrerequisiteAssignment({ GLOBAL_REFERENCE: accum }));
+                prerequisiteAssignments.push(
+                  buildPrerequisiteAssignment({ GLOBAL_REFERENCE: accum }),
+                );
                 return t.memberExpression(accum, t.identifier(curr));
               }, t.memberExpression(t.identifier("global"), t.identifier(members[0])));
             }
@@ -125,13 +141,15 @@ export default function ({ types: t }) {
             GLOBAL_TO_ASSIGN: globalToAssign,
           });
 
-          last.replaceWith(buildWrapper({
-            MODULE_NAME: moduleName,
-            AMD_ARGUMENTS: amdArgs,
-            COMMON_ARGUMENTS: commonArgs,
-            GLOBAL_EXPORT: globalExport,
-            FUNC: func,
-          }));
+          last.replaceWith(
+            buildWrapper({
+              MODULE_NAME: moduleName,
+              AMD_ARGUMENTS: amdArgs,
+              COMMON_ARGUMENTS: commonArgs,
+              GLOBAL_EXPORT: globalExport,
+              FUNC: func,
+            }),
+          );
         },
       },
     },
diff --git a/packages/babel-plugin-transform-es2015-object-super/src/index.js b/packages/babel-plugin-transform-es2015-object-super/src/index.js
index 71ddc26737..62f360382e 100644
--- a/packages/babel-plugin-transform-es2015-object-super/src/index.js
+++ b/packages/babel-plugin-transform-es2015-object-super/src/index.js
@@ -13,20 +13,27 @@ function replacePropertySuper(path, node, scope, getObjectRef, file) {
   replaceSupers.replace();
 }
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   return {
     visitor: {
       ObjectExpression(path, state) {
         let objectRef;
-        const getObjectRef = () => objectRef = objectRef || path.scope.generateUidIdentifier("obj");
+        const getObjectRef = () =>
+          (objectRef = objectRef || path.scope.generateUidIdentifier("obj"));
 
-        path.get("properties").forEach((propertyPath) => {
+        path.get("properties").forEach(propertyPath => {
           if (!propertyPath.isMethod()) return;
 
           const propPaths: Array = path.get("properties");
           for (let propPath of propPaths) {
             if (propPath.isObjectProperty()) propPath = propPath.get("value");
-            replacePropertySuper(propPath, propPath.node, path.scope, getObjectRef, state);
+            replacePropertySuper(
+              propPath,
+              propPath.node,
+              path.scope,
+              getObjectRef,
+              state,
+            );
           }
         });
 
diff --git a/packages/babel-plugin-transform-es2015-parameters/src/index.js b/packages/babel-plugin-transform-es2015-parameters/src/index.js
index 673fbc5359..e9b4117ccd 100644
--- a/packages/babel-plugin-transform-es2015-parameters/src/index.js
+++ b/packages/babel-plugin-transform-es2015-parameters/src/index.js
@@ -5,23 +5,28 @@ import * as destructuring from "./destructuring";
 import * as def from "./default";
 import * as rest from "./rest";
 
-export default function () {
+export default function() {
   return {
-    visitor: visitors.merge([{
-      ArrowFunctionExpression(path) {
-        // In some conversion cases, it may have already been converted to a function while this callback
-        // was queued up.
-        if (!path.isArrowFunctionExpression()) return;
+    visitor: visitors.merge([
+      {
+        ArrowFunctionExpression(path) {
+          // In some conversion cases, it may have already been converted to a function while this callback
+          // was queued up.
+          if (!path.isArrowFunctionExpression()) return;
 
-        // default/rest visitors require access to `arguments`
-        const params: Array<NodePath> = path.get("params");
-        for (const param of params) {
-          if (param.isRestElement() || param.isAssignmentPattern()) {
-            path.arrowFunctionToExpression();
-            break;
+          // default/rest visitors require access to `arguments`
+          const params: Array<NodePath> = path.get("params");
+          for (const param of params) {
+            if (param.isRestElement() || param.isAssignmentPattern()) {
+              path.arrowFunctionToExpression();
+              break;
+            }
           }
-        }
+        },
       },
-    }, destructuring.visitor, rest.visitor, def.visitor]),
+      destructuring.visitor,
+      rest.visitor,
+      def.visitor,
+    ]),
   };
 }
diff --git a/packages/babel-plugin-transform-es2015-parameters/src/rest.js b/packages/babel-plugin-transform-es2015-parameters/src/rest.js
index 1afa0e4b74..141fa582c7 100644
--- a/packages/babel-plugin-transform-es2015-parameters/src/rest.js
+++ b/packages/babel-plugin-transform-es2015-parameters/src/rest.js
@@ -47,7 +47,7 @@ const memberExpressionOptimisationVisitor = {
     path.skip();
   },
 
-  "Function|ClassProperty": function (path, state) {
+  "Function|ClassProperty": function(path, state) {
     // Detect whether any reference to rest is contained in nested functions to
     // determine if deopt is necessary.
     const oldNoOptimise = state.noOptimise;
@@ -86,38 +86,29 @@ const memberExpressionOptimisationVisitor = {
       if (parentPath.isMemberExpression({ object: node })) {
         const grandparentPath = parentPath.parentPath;
 
-        const argsOptEligible = !state.deopted && !(
-          // ex: `args[0] = "whatever"`
+        const argsOptEligible =
+          !state.deopted &&
+          !// ex: `args[0] = "whatever"`
           (
-            grandparentPath.isAssignmentExpression() &&
-            parentPath.node === grandparentPath.node.left
-          ) ||
-
-          // ex: `[args[0]] = ["whatever"]`
-          grandparentPath.isLVal() ||
-
-          // ex: `for (rest[0] in this)`
-          // ex: `for (rest[0] of this)`
-          grandparentPath.isForXStatement() ||
-
-          // ex: `++args[0]`
-          // ex: `args[0]--`
-          grandparentPath.isUpdateExpression() ||
-
-          // ex: `delete args[0]`
-          grandparentPath.isUnaryExpression({ operator: "delete" }) ||
-
-          // ex: `args[0]()`
-          // ex: `new args[0]()`
-          // ex: `new args[0]`
-          (
-            (
-              grandparentPath.isCallExpression() ||
-              grandparentPath.isNewExpression()
-            ) &&
-            parentPath.node === grandparentPath.node.callee
-          )
-        );
+            (grandparentPath.isAssignmentExpression() &&
+              parentPath.node === grandparentPath.node.left) ||
+            // ex: `[args[0]] = ["whatever"]`
+            grandparentPath.isLVal() ||
+            // ex: `for (rest[0] in this)`
+            // ex: `for (rest[0] of this)`
+            grandparentPath.isForXStatement() ||
+            // ex: `++args[0]`
+            // ex: `args[0]--`
+            grandparentPath.isUpdateExpression() ||
+            // ex: `delete args[0]`
+            grandparentPath.isUnaryExpression({ operator: "delete" }) ||
+            // ex: `args[0]()`
+            // ex: `new args[0]()`
+            // ex: `new args[0]`
+            ((grandparentPath.isCallExpression() ||
+              grandparentPath.isNewExpression()) &&
+              parentPath.node === grandparentPath.node.callee)
+          );
 
         if (argsOptEligible) {
           if (parentPath.node.computed) {
@@ -127,9 +118,8 @@ const memberExpressionOptimisationVisitor = {
               state.candidates.push({ cause: "indexGetter", path });
               return;
             }
-          }
-          // args.length
-          else if (parentPath.node.property.name === "length") {
+          } else if (parentPath.node.property.name === "length") {
+            // args.length
             state.candidates.push({ cause: "lengthGetter", path });
             return;
           }
@@ -177,32 +167,42 @@ function optimiseIndexGetter(path, argsId, offset) {
     // Avoid unnecessary '+ 0'
     index = path.parent.property;
   } else {
-    index = t.binaryExpression("+", path.parent.property, t.numericLiteral(offset));
+    index = t.binaryExpression(
+      "+",
+      path.parent.property,
+      t.numericLiteral(offset),
+    );
   }
 
   const { scope } = path;
   if (!scope.isPure(index)) {
     const temp = scope.generateUidIdentifierBasedOnNode(index);
     scope.push({ id: temp, kind: "var" });
-    path.parentPath.replaceWith(restIndexImpure({
-      ARGUMENTS: argsId,
-      INDEX: index,
-      REF: temp,
-    }));
+    path.parentPath.replaceWith(
+      restIndexImpure({
+        ARGUMENTS: argsId,
+        INDEX: index,
+        REF: temp,
+      }),
+    );
   } else {
-    path.parentPath.replaceWith(restIndex({
-      ARGUMENTS: argsId,
-      INDEX: index,
-    }));
+    path.parentPath.replaceWith(
+      restIndex({
+        ARGUMENTS: argsId,
+        INDEX: index,
+      }),
+    );
   }
 }
 
 function optimiseLengthGetter(path, argsId, offset) {
   if (offset) {
-    path.parentPath.replaceWith(restLength({
-      ARGUMENTS: argsId,
-      OFFSET: t.numericLiteral(offset),
-    }));
+    path.parentPath.replaceWith(
+      restLength({
+        ARGUMENTS: argsId,
+        OFFSET: t.numericLiteral(offset),
+      }),
+    );
   } else {
     path.replaceWith(argsId);
   }
@@ -266,7 +266,7 @@ export const visitor = {
     }
 
     state.references = state.references.concat(
-      state.candidates.map(({ path }) => path)
+      state.candidates.map(({ path }) => path),
     );
 
     const start = t.numericLiteral(node.params.length);
@@ -290,7 +290,7 @@ export const visitor = {
       arrLen = t.conditionalExpression(
         t.binaryExpression(">", len, start),
         t.binaryExpression("-", len, start),
-        t.numericLiteral(0)
+        t.numericLiteral(0),
       );
     }
 
@@ -311,10 +311,12 @@ export const visitor = {
       // perform allocation at the lowest common ancestor of all references
       loop._blockHoist = 1;
 
-      let target = path.getEarliestCommonAncestorFrom(state.references).getStatementParent();
+      let target = path
+        .getEarliestCommonAncestorFrom(state.references)
+        .getStatementParent();
 
       // don't perform the allocation inside a loop
-      target.findParent((path) => {
+      target.findParent(path => {
         if (path.isLoop()) {
           target = path;
         } else {
diff --git a/packages/babel-plugin-transform-es2015-shorthand-properties/src/index.js b/packages/babel-plugin-transform-es2015-shorthand-properties/src/index.js
index fdf4c17fda..220b93c4e7 100644
--- a/packages/babel-plugin-transform-es2015-shorthand-properties/src/index.js
+++ b/packages/babel-plugin-transform-es2015-shorthand-properties/src/index.js
@@ -1,19 +1,21 @@
 import * as t from "babel-types";
 
-export default function () {
+export default function() {
   return {
     visitor: {
       ObjectMethod(path) {
         const { node } = path;
         if (node.kind === "method") {
-          const func = t.functionExpression(null, node.params, node.body, node.generator, node.async);
+          const func = t.functionExpression(
+            null,
+            node.params,
+            node.body,
+            node.generator,
+            node.async,
+          );
           func.returnType = node.returnType;
 
-          path.replaceWith(t.objectProperty(
-            node.key,
-            func,
-            node.computed
-          ));
+          path.replaceWith(t.objectProperty(node.key, func, node.computed));
         }
       },
 
diff --git a/packages/babel-plugin-transform-es2015-spread/src/index.js b/packages/babel-plugin-transform-es2015-spread/src/index.js
index d1c8697ab3..48d196e941 100644
--- a/packages/babel-plugin-transform-es2015-spread/src/index.js
+++ b/packages/babel-plugin-transform-es2015-spread/src/index.js
@@ -1,6 +1,9 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function getSpreadLiteral(spread, scope, state) {
-    if (state.opts.loose && !t.isIdentifier(spread.argument, { name: "arguments" })) {
+    if (
+      state.opts.loose &&
+      !t.isIdentifier(spread.argument, { name: "arguments" })
+    ) {
       return spread.argument;
     } else {
       return scope.toArray(spread.argument, true);
@@ -55,7 +58,12 @@ export default function ({ types: t }) {
           first = t.arrayExpression([]);
         }
 
-        path.replaceWith(t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes));
+        path.replaceWith(
+          t.callExpression(
+            t.memberExpression(first, t.identifier("concat")),
+            nodes,
+          ),
+        );
       },
 
       CallExpression(path, state) {
@@ -80,7 +88,12 @@ export default function ({ types: t }) {
 
         const first = nodes.shift();
         if (nodes.length) {
-          node.arguments.push(t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes));
+          node.arguments.push(
+            t.callExpression(
+              t.memberExpression(first, t.identifier("concat")),
+              nodes,
+            ),
+          );
         } else {
           node.arguments.push(first);
         }
@@ -116,25 +129,29 @@ export default function ({ types: t }) {
 
         const context = t.arrayExpression([t.nullLiteral()]);
 
+        args = t.callExpression(
+          t.memberExpression(context, t.identifier("concat")),
+          nodes,
+        );
 
-        args = t.callExpression(t.memberExpression(context, t.identifier("concat")), nodes);
-
-        path.replaceWith(t.newExpression(
-          t.callExpression(
-            t.memberExpression(
+        path.replaceWith(
+          t.newExpression(
+            t.callExpression(
               t.memberExpression(
                 t.memberExpression(
-                  t.identifier("Function"),
-                  t.identifier("prototype"),
+                  t.memberExpression(
+                    t.identifier("Function"),
+                    t.identifier("prototype"),
+                  ),
+                  t.identifier("bind"),
                 ),
-                t.identifier("bind")
+                t.identifier("apply"),
               ),
-              t.identifier("apply")
+              [node.callee, args],
             ),
-            [node.callee, args]
+            [],
           ),
-          []
-        ));
+        );
       },
     },
   };
diff --git a/packages/babel-plugin-transform-es2015-sticky-regex/src/index.js b/packages/babel-plugin-transform-es2015-sticky-regex/src/index.js
index 0798fa002b..25748ba7f4 100644
--- a/packages/babel-plugin-transform-es2015-sticky-regex/src/index.js
+++ b/packages/babel-plugin-transform-es2015-sticky-regex/src/index.js
@@ -1,17 +1,19 @@
 import * as regex from "babel-helper-regex";
 import * as t from "babel-types";
 
-export default function () {
+export default function() {
   return {
     visitor: {
       RegExpLiteral(path) {
         const { node } = path;
         if (!regex.is(node, "y")) return;
 
-        path.replaceWith(t.newExpression(t.identifier("RegExp"), [
-          t.stringLiteral(node.pattern),
-          t.stringLiteral(node.flags),
-        ]));
+        path.replaceWith(
+          t.newExpression(t.identifier("RegExp"), [
+            t.stringLiteral(node.pattern),
+            t.stringLiteral(node.flags),
+          ]),
+        );
       },
     },
   };
diff --git a/packages/babel-plugin-transform-es2015-template-literals/src/index.js b/packages/babel-plugin-transform-es2015-template-literals/src/index.js
index ab45375eff..f6ae7951f1 100644
--- a/packages/babel-plugin-transform-es2015-template-literals/src/index.js
+++ b/packages/babel-plugin-transform-es2015-template-literals/src/index.js
@@ -1,5 +1,4 @@
-export default function ({ types: t }) {
-
+export default function({ types: t }) {
   function buildConcatCallExressions(items) {
     let avail = true;
     return items.reduce(function(left, right) {
@@ -15,7 +14,7 @@ export default function ({ types: t }) {
       }
       return t.callExpression(
         t.memberExpression(left, t.identifier("concat")),
-        [right]
+        [right],
       );
     });
   }
@@ -23,7 +22,6 @@ export default function ({ types: t }) {
   return {
     visitor: {
       TaggedTemplateExpression(path, state) {
-
         const { node } = path;
         const { quasi } = node;
 
@@ -32,9 +30,10 @@ export default function ({ types: t }) {
 
         for (const elem of (quasi.quasis: Array)) {
           const { raw, cooked } = elem.value;
-          const value = cooked == null
-            ? path.scope.buildUndefinedNode()
-            : t.stringLiteral(cooked);
+          const value =
+            cooked == null
+              ? path.scope.buildUndefinedNode()
+              : t.stringLiteral(cooked);
 
           strings.push(value);
           raws.push(t.stringLiteral(raw));
@@ -46,7 +45,7 @@ export default function ({ types: t }) {
         const templateObject = state.file.addTemplateObject(
           templateName,
           t.arrayExpression(strings),
-          t.arrayExpression(raws)
+          t.arrayExpression(raws),
         );
 
         const args = [templateObject].concat(quasi.expressions);
@@ -75,7 +74,8 @@ export default function ({ types: t }) {
 
         // since `+` is left-to-right associative
         // ensure the first node is a string if first/second isn't
-        const considerSecondNode = state.opts.spec || !t.isStringLiteral(nodes[1]);
+        const considerSecondNode =
+          state.opts.spec || !t.isStringLiteral(nodes[1]);
         if (!t.isStringLiteral(nodes[0]) && considerSecondNode) {
           nodes.unshift(t.stringLiteral(""));
         }
diff --git a/packages/babel-plugin-transform-es2015-typeof-symbol/src/index.js b/packages/babel-plugin-transform-es2015-typeof-symbol/src/index.js
index d5d7ae067d..145cf41ff6 100644
--- a/packages/babel-plugin-transform-es2015-typeof-symbol/src/index.js
+++ b/packages/babel-plugin-transform-es2015-typeof-symbol/src/index.js
@@ -1,4 +1,4 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   const IGNORE = Symbol();
 
   return {
@@ -14,7 +14,7 @@ export default function ({ types: t }) {
       UnaryExpression(path) {
         const { node, parent } = path;
         if (node[IGNORE]) return;
-        if (path.find((path) => path.node && !!path.node._generated)) return;
+        if (path.find(path => path.node && !!path.node._generated)) return;
 
         if (
           path.parentPath.isBinaryExpression() &&
@@ -24,7 +24,8 @@ export default function ({ types: t }) {
           // need to handle symbols
           const opposite = path.getOpposite();
           if (
-            opposite.isLiteral() && opposite.node.value !== "symbol" &&
+            opposite.isLiteral() &&
+            opposite.node.value !== "symbol" &&
             opposite.node.value !== "object"
           ) {
             return;
@@ -32,16 +33,20 @@ export default function ({ types: t }) {
         }
 
         if (node.operator === "typeof") {
-          const call = t.callExpression(this.addHelper("typeof"), [node.argument]);
+          const call = t.callExpression(this.addHelper("typeof"), [
+            node.argument,
+          ]);
           if (path.get("argument").isIdentifier()) {
             const undefLiteral = t.stringLiteral("undefined");
             const unary = t.unaryExpression("typeof", node.argument);
             unary[IGNORE] = true;
-            path.replaceWith(t.conditionalExpression(
-              t.binaryExpression("===", unary, undefLiteral),
-              undefLiteral,
-              call
-            ));
+            path.replaceWith(
+              t.conditionalExpression(
+                t.binaryExpression("===", unary, undefLiteral),
+                undefLiteral,
+                call,
+              ),
+            );
           } else {
             path.replaceWith(call);
           }
diff --git a/packages/babel-plugin-transform-es2015-unicode-regex/src/index.js b/packages/babel-plugin-transform-es2015-unicode-regex/src/index.js
index 0e537eeb5b..6af40c3918 100644
--- a/packages/babel-plugin-transform-es2015-unicode-regex/src/index.js
+++ b/packages/babel-plugin-transform-es2015-unicode-regex/src/index.js
@@ -1,7 +1,7 @@
 import rewritePattern from "regexpu-core";
 import * as regex from "babel-helper-regex";
 
-export default function () {
+export default function() {
   return {
     visitor: {
       RegExpLiteral({ node }) {
diff --git a/packages/babel-plugin-transform-es3-member-expression-literals/src/index.js b/packages/babel-plugin-transform-es3-member-expression-literals/src/index.js
index ddcea660c1..a4a49f9080 100644
--- a/packages/babel-plugin-transform-es3-member-expression-literals/src/index.js
+++ b/packages/babel-plugin-transform-es3-member-expression-literals/src/index.js
@@ -1,10 +1,14 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   return {
     visitor: {
       MemberExpression: {
         exit({ node }) {
           const prop = node.property;
-          if (!node.computed && t.isIdentifier(prop) && !t.isValidIdentifier(prop.name)) {
+          if (
+            !node.computed &&
+            t.isIdentifier(prop) &&
+            !t.isValidIdentifier(prop.name)
+          ) {
             // foo.default -> foo["default"]
             node.property = t.stringLiteral(prop.name);
             node.computed = true;
diff --git a/packages/babel-plugin-transform-es3-property-literals/src/index.js b/packages/babel-plugin-transform-es3-property-literals/src/index.js
index b85cfc84a4..558e8ff5fe 100644
--- a/packages/babel-plugin-transform-es3-property-literals/src/index.js
+++ b/packages/babel-plugin-transform-es3-property-literals/src/index.js
@@ -1,10 +1,14 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   return {
     visitor: {
       ObjectProperty: {
         exit({ node }) {
           const key = node.key;
-          if (!node.computed && t.isIdentifier(key) && !t.isValidIdentifier(key.name)) {
+          if (
+            !node.computed &&
+            t.isIdentifier(key) &&
+            !t.isValidIdentifier(key.name)
+          ) {
             // default: "bar" -> "default": "bar"
             node.key = t.stringLiteral(key.name);
           }
diff --git a/packages/babel-plugin-transform-es5-property-mutators/src/index.js b/packages/babel-plugin-transform-es5-property-mutators/src/index.js
index 243b690227..3d22f6d680 100644
--- a/packages/babel-plugin-transform-es5-property-mutators/src/index.js
+++ b/packages/babel-plugin-transform-es5-property-mutators/src/index.js
@@ -1,6 +1,6 @@
 import * as defineMap from "babel-helper-define-map";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   return {
     visitor: {
       ObjectExpression(path, file) {
@@ -16,7 +16,7 @@ export default function ({ types: t }) {
 
         const mutatorMap = {};
 
-        node.properties = node.properties.filter(function (prop) {
+        node.properties = node.properties.filter(function(prop) {
           if (!prop.computed && (prop.kind === "get" || prop.kind === "set")) {
             defineMap.push(mutatorMap, prop, null, file);
             return false;
@@ -25,10 +25,15 @@ export default function ({ types: t }) {
           }
         });
 
-        path.replaceWith(t.callExpression(
-          t.memberExpression(t.identifier("Object"), t.identifier("defineProperties")),
-          [node, defineMap.toDefineObject(mutatorMap)]
-        ));
+        path.replaceWith(
+          t.callExpression(
+            t.memberExpression(
+              t.identifier("Object"),
+              t.identifier("defineProperties"),
+            ),
+            [node, defineMap.toDefineObject(mutatorMap)],
+          ),
+        );
       },
     },
   };
diff --git a/packages/babel-plugin-transform-eval/src/index.js b/packages/babel-plugin-transform-eval/src/index.js
index 14486299c0..9e86f2adf1 100644
--- a/packages/babel-plugin-transform-eval/src/index.js
+++ b/packages/babel-plugin-transform-eval/src/index.js
@@ -1,8 +1,11 @@
-export default function ({ parse, traverse }) {
+export default function({ parse, traverse }) {
   return {
     visitor: {
       CallExpression(path) {
-        if (path.get("callee").isIdentifier({ name: "eval" }) && path.node.arguments.length === 1) {
+        if (
+          path.get("callee").isIdentifier({ name: "eval" }) &&
+          path.node.arguments.length === 1
+        ) {
           const evaluate = path.get("arguments")[0].evaluate();
           if (!evaluate.confident) return;
 
diff --git a/packages/babel-plugin-transform-exponentiation-operator/src/index.js b/packages/babel-plugin-transform-exponentiation-operator/src/index.js
index 8756cd81d0..9ac165068c 100644
--- a/packages/babel-plugin-transform-exponentiation-operator/src/index.js
+++ b/packages/babel-plugin-transform-exponentiation-operator/src/index.js
@@ -1,7 +1,7 @@
 import build from "babel-helper-builder-binary-assignment-operator-visitor";
 import syntaxExponentiationOperator from "babel-plugin-syntax-exponentiation-operator";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   return {
     inherits: syntaxExponentiationOperator,
 
@@ -9,7 +9,10 @@ export default function ({ types: t }) {
       operator: "**",
 
       build(left, right) {
-        return t.callExpression(t.memberExpression(t.identifier("Math"), t.identifier("pow")), [left, right]);
+        return t.callExpression(
+          t.memberExpression(t.identifier("Math"), t.identifier("pow")),
+          [left, right],
+        );
       },
     }),
   };
diff --git a/packages/babel-plugin-transform-export-extensions/src/index.js b/packages/babel-plugin-transform-export-extensions/src/index.js
index b79bfc8b8b..ada6db115f 100644
--- a/packages/babel-plugin-transform-export-extensions/src/index.js
+++ b/packages/babel-plugin-transform-export-extensions/src/index.js
@@ -1,9 +1,14 @@
 import syntaxExportExtensions from "babel-plugin-syntax-export-extensions";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function build(node, nodes, scope) {
     const first = node.specifiers[0];
-    if (!t.isExportNamespaceSpecifier(first) && !t.isExportDefaultSpecifier(first)) return;
+    if (
+      !t.isExportNamespaceSpecifier(first) &&
+      !t.isExportDefaultSpecifier(first)
+    ) {
+      return;
+    }
 
     const specifier = node.specifiers.shift();
     const uid = scope.generateUidIdentifier(specifier.exported.name);
@@ -16,7 +21,11 @@ export default function ({ types: t }) {
     }
 
     nodes.push(t.importDeclaration([newSpecifier], node.source));
-    nodes.push(t.exportNamedDeclaration(null, [t.exportSpecifier(uid, specifier.exported)]));
+    nodes.push(
+      t.exportNamedDeclaration(null, [
+        t.exportSpecifier(uid, specifier.exported),
+      ]),
+    );
 
     build(node, nodes, scope);
   }
diff --git a/packages/babel-plugin-transform-flow-comments/src/index.js b/packages/babel-plugin-transform-flow-comments/src/index.js
index f2eeb2710a..21e383af66 100644
--- a/packages/babel-plugin-transform-flow-comments/src/index.js
+++ b/packages/babel-plugin-transform-flow-comments/src/index.js
@@ -1,13 +1,16 @@
 import syntaxFlow from "babel-plugin-syntax-flow";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function wrapInFlowComment(path, parent) {
     path.addComment("trailing", generateComment(path, parent));
     path.replaceWith(t.noop());
   }
 
   function generateComment(path, parent) {
-    let comment = path.getSource().replace(/\*-\//g, "*-ESCAPED/").replace(/\*\//g, "*-/");
+    let comment = path
+      .getSource()
+      .replace(/\*-\//g, "*-ESCAPED/")
+      .replace(/\*\//g, "*-/");
     if (parent && parent.optional) comment = "?" + comment;
     if (comment[0] !== ":") comment = ":: " + comment;
     return comment;
@@ -19,7 +22,9 @@ export default function ({ types: t }) {
     visitor: {
       TypeCastExpression(path) {
         const { node } = path;
-        path.get("expression").addComment("trailing", generateComment(path.get("typeAnnotation")));
+        path
+          .get("expression")
+          .addComment("trailing", generateComment(path.get("typeAnnotation")));
         path.replaceWith(t.parenthesizedExpression(node.expression));
       },
 
@@ -41,7 +46,7 @@ export default function ({ types: t }) {
       // strip optional property from function params - facebook/fbjs#17
       Function: {
         exit({ node }) {
-          node.params.forEach((param) => param.optional = false);
+          node.params.forEach(param => (param.optional = false));
         },
       },
 
@@ -54,7 +59,11 @@ export default function ({ types: t }) {
       // support `export type a = {}` - #8 Error: You passed path.replaceWith() a falsy node
       "ExportNamedDeclaration|Flow"(path) {
         const { node, parent } = path;
-        if (t.isExportNamedDeclaration(node) && node.exportKind !== "type" && !t.isFlow(node.declaration)) {
+        if (
+          t.isExportNamedDeclaration(node) &&
+          node.exportKind !== "type" &&
+          !t.isFlow(node.declaration)
+        ) {
           return;
         }
         wrapInFlowComment(path, parent);
@@ -63,7 +72,11 @@ export default function ({ types: t }) {
       // support `import type A` and `import typeof A` #10
       ImportDeclaration(path) {
         const { node, parent } = path;
-        if (t.isImportDeclaration(node) && node.importKind !== "type" && node.importKind !== "typeof") {
+        if (
+          t.isImportDeclaration(node) &&
+          node.importKind !== "type" &&
+          node.importKind !== "typeof"
+        ) {
           return;
         }
         wrapInFlowComment(path, parent);
diff --git a/packages/babel-plugin-transform-flow-strip-types/src/index.js b/packages/babel-plugin-transform-flow-strip-types/src/index.js
index 28b1330f27..5c5d73d828 100644
--- a/packages/babel-plugin-transform-flow-strip-types/src/index.js
+++ b/packages/babel-plugin-transform-flow-strip-types/src/index.js
@@ -1,6 +1,6 @@
 import syntaxFlow from "babel-plugin-syntax-flow";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   const FLOW_DIRECTIVE = "@flow";
 
   return {
@@ -50,7 +50,7 @@ export default function ({ types: t }) {
 
         // We do this here instead of in a `ClassProperty` visitor because the class transform
         // would transform the class before we reached the class property.
-        path.get("body.body").forEach((child) => {
+        path.get("body.body").forEach(child => {
           if (child.isClassProperty()) {
             child.node.typeAnnotation = null;
             if (!child.node.value) child.remove();
diff --git a/packages/babel-plugin-transform-function-bind/src/index.js b/packages/babel-plugin-transform-function-bind/src/index.js
index c92e147397..322363a658 100644
--- a/packages/babel-plugin-transform-function-bind/src/index.js
+++ b/packages/babel-plugin-transform-function-bind/src/index.js
@@ -1,6 +1,6 @@
 import syntaxFunctionBind from "babel-plugin-syntax-function-bind";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function getTempId(scope) {
     let id = scope.path.getData("functionBind");
     if (id) return id;
@@ -25,7 +25,11 @@ export default function ({ types: t }) {
         bind.callee,
       ]);
     } else {
-      bind.callee.object = t.assignmentExpression("=", tempId, bind.callee.object);
+      bind.callee.object = t.assignmentExpression(
+        "=",
+        tempId,
+        bind.callee.object,
+      );
     }
     return tempId;
   }
@@ -46,7 +50,12 @@ export default function ({ types: t }) {
       BindExpression(path) {
         const { node, scope } = path;
         const context = inferBindContext(node, scope);
-        path.replaceWith(t.callExpression(t.memberExpression(node.callee, t.identifier("bind")), [context]));
+        path.replaceWith(
+          t.callExpression(
+            t.memberExpression(node.callee, t.identifier("bind")),
+            [context],
+          ),
+        );
       },
     },
   };
diff --git a/packages/babel-plugin-transform-jscript/src/index.js b/packages/babel-plugin-transform-jscript/src/index.js
index a34268656e..205791fc54 100644
--- a/packages/babel-plugin-transform-jscript/src/index.js
+++ b/packages/babel-plugin-transform-jscript/src/index.js
@@ -1,4 +1,4 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   return {
     visitor: {
       FunctionExpression: {
@@ -7,13 +7,19 @@ export default function ({ types: t }) {
           if (!node.id) return;
           node._ignoreUserWhitespace = true;
 
-          path.replaceWith(t.callExpression(
-            t.functionExpression(null, [], t.blockStatement([
-              t.toStatement(node),
-              t.returnStatement(node.id),
-            ])),
-            []
-          ));
+          path.replaceWith(
+            t.callExpression(
+              t.functionExpression(
+                null,
+                [],
+                t.blockStatement([
+                  t.toStatement(node),
+                  t.returnStatement(node.id),
+                ]),
+              ),
+              [],
+            ),
+          );
         },
       },
     },
diff --git a/packages/babel-plugin-transform-numeric-separator/src/index.js b/packages/babel-plugin-transform-numeric-separator/src/index.js
index f398163784..37c26e529c 100644
--- a/packages/babel-plugin-transform-numeric-separator/src/index.js
+++ b/packages/babel-plugin-transform-numeric-separator/src/index.js
@@ -1,7 +1,6 @@
 import syntaxNumericSeparator from "babel-plugin-syntax-numeric-separator";
 
-export default function ({ types: t }) {
-
+export default function({ types: t }) {
   function replacer(value) {
     return value.replace(/_/g, "");
   }
diff --git a/packages/babel-plugin-transform-object-assign/src/index.js b/packages/babel-plugin-transform-object-assign/src/index.js
index 067a793bdd..42df9df70a 100644
--- a/packages/babel-plugin-transform-object-assign/src/index.js
+++ b/packages/babel-plugin-transform-object-assign/src/index.js
@@ -1,7 +1,7 @@
-export default function () {
+export default function() {
   return {
     visitor: {
-      CallExpression: function (path, file) {
+      CallExpression: function(path, file) {
         if (path.get("callee").matchesPattern("Object.assign")) {
           path.node.callee = file.addHelper("extends");
         }
diff --git a/packages/babel-plugin-transform-object-rest-spread/src/index.js b/packages/babel-plugin-transform-object-rest-spread/src/index.js
index 6ffcc0642f..16a78e1dd3 100644
--- a/packages/babel-plugin-transform-object-rest-spread/src/index.js
+++ b/packages/babel-plugin-transform-object-rest-spread/src/index.js
@@ -1,6 +1,6 @@
 import syntaxObjectRestSpread from "babel-plugin-syntax-object-rest-spread";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function hasRestElement(path) {
     let foundRestElement = false;
     path.traverse({
@@ -13,7 +13,7 @@ export default function ({ types: t }) {
   }
 
   function hasSpread(node) {
-    for (const prop of (node.properties)) {
+    for (const prop of node.properties) {
       if (t.isSpreadElement(prop)) {
         return true;
       }
@@ -35,12 +35,10 @@ export default function ({ types: t }) {
 
     return [
       restElement.argument,
-      t.callExpression(
-        file.addHelper("objectWithoutProperties"), [
-          objRef,
-          t.arrayExpression(keys),
-        ]
-      ),
+      t.callExpression(file.addHelper("objectWithoutProperties"), [
+        objRef,
+        t.arrayExpression(keys),
+      ]),
     ];
   }
 
@@ -87,76 +85,85 @@ export default function ({ types: t }) {
       // adapted from transform-es2015-destructuring/src/index.js#pushObjectRest
       // const { a, ...b } = c;
       VariableDeclarator(path, file) {
-        if (!path.get("id").isObjectPattern()) { return; }
+        if (!path.get("id").isObjectPattern()) {
+          return;
+        }
 
         let insertionPath = path;
 
-        path.get("id").traverse({
-          RestElement(path) {
-            if (
-              // skip single-property case, e.g.
-              // const { ...x } = foo();
-              // since the RHS will not be duplicated
-              this.originalPath.node.id.properties.length > 1 &&
-              !t.isIdentifier(this.originalPath.node.init)
-            ) {
-              // const { a, ...b } = foo();
-              // to avoid calling foo() twice, as a first step convert it to:
-              // const _foo = foo(),
-              //       { a, ...b } = _foo;
-              const initRef = path.scope.generateUidIdentifierBasedOnNode(
-                this.originalPath.node.init, "ref");
-              // insert _foo = foo()
-              this.originalPath.insertBefore(t.variableDeclarator(initRef,
-                this.originalPath.node.init));
-              // replace foo() with _foo
-              this.originalPath.replaceWith(t.variableDeclarator(
-                this.originalPath.node.id, initRef));
+        path.get("id").traverse(
+          {
+            RestElement(path) {
+              if (
+                // skip single-property case, e.g.
+                // const { ...x } = foo();
+                // since the RHS will not be duplicated
+                this.originalPath.node.id.properties.length > 1 &&
+                !t.isIdentifier(this.originalPath.node.init)
+              ) {
+                // const { a, ...b } = foo();
+                // to avoid calling foo() twice, as a first step convert it to:
+                // const _foo = foo(),
+                //       { a, ...b } = _foo;
+                const initRef = path.scope.generateUidIdentifierBasedOnNode(
+                  this.originalPath.node.init,
+                  "ref",
+                );
+                // insert _foo = foo()
+                this.originalPath.insertBefore(
+                  t.variableDeclarator(initRef, this.originalPath.node.init),
+                );
+                // replace foo() with _foo
+                this.originalPath.replaceWith(
+                  t.variableDeclarator(this.originalPath.node.id, initRef),
+                );
 
-              return;
-            }
-
-            let ref = this.originalPath.node.init;
-            const refPropertyPath = [];
-
-            path.findParent((path) => {
-              if (path.isObjectProperty()) {
-                refPropertyPath.unshift(path.node.key.name);
-              } else if (path.isVariableDeclarator()) {
-                return true;
+                return;
               }
-            });
 
-            if (refPropertyPath.length) {
-              refPropertyPath.forEach((prop) => {
-                ref = t.memberExpression(ref, t.identifier(prop));
+              let ref = this.originalPath.node.init;
+              const refPropertyPath = [];
+
+              path.findParent(path => {
+                if (path.isObjectProperty()) {
+                  refPropertyPath.unshift(path.node.key.name);
+                } else if (path.isVariableDeclarator()) {
+                  return true;
+                }
               });
-            }
 
-            const [ argument, callExpression ] = createObjectSpread(
-              file,
-              path.parentPath.node.properties,
-              ref
-            );
+              if (refPropertyPath.length) {
+                refPropertyPath.forEach(prop => {
+                  ref = t.memberExpression(ref, t.identifier(prop));
+                });
+              }
 
-            insertionPath.insertAfter(
-              t.variableDeclarator(
-                argument,
-                callExpression
-              )
-            );
+              const [argument, callExpression] = createObjectSpread(
+                file,
+                path.parentPath.node.properties,
+                ref,
+              );
 
-            insertionPath = insertionPath.getSibling(insertionPath.key + 1);
+              insertionPath.insertAfter(
+                t.variableDeclarator(argument, callExpression),
+              );
 
-            if (path.parentPath.node.properties.length === 0) {
-              path.findParent(
-                (path) => path.isObjectProperty() || path.isVariableDeclarator()
-              ).remove();
-            }
+              insertionPath = insertionPath.getSibling(insertionPath.key + 1);
+
+              if (path.parentPath.node.properties.length === 0) {
+                path
+                  .findParent(
+                    path =>
+                      path.isObjectProperty() || path.isVariableDeclarator(),
+                  )
+                  .remove();
+              }
+            },
           },
-        }, {
-          originalPath: path,
-        });
+          {
+            originalPath: path,
+          },
+        );
       },
       // taken from transform-es2015-destructuring/src/index.js#visitor
       // export var { a, ...b } = c;
@@ -190,28 +197,36 @@ export default function ({ types: t }) {
           const nodes = [];
 
           let ref;
-          if (path.isCompletionRecord() || path.parentPath.isExpressionStatement()) {
-            ref = path.scope.generateUidIdentifierBasedOnNode(path.node.right, "ref");
+          if (
+            path.isCompletionRecord() ||
+            path.parentPath.isExpressionStatement()
+          ) {
+            ref = path.scope.generateUidIdentifierBasedOnNode(
+              path.node.right,
+              "ref",
+            );
 
-            nodes.push(t.variableDeclaration("var", [
-              t.variableDeclarator(ref, path.node.right),
-            ]));
+            nodes.push(
+              t.variableDeclaration("var", [
+                t.variableDeclarator(ref, path.node.right),
+              ]),
+            );
           }
 
-          const [ argument, callExpression ] = createObjectSpread(
+          const [argument, callExpression] = createObjectSpread(
             file,
             path.node.left.properties,
-            ref
+            ref,
           );
 
           const nodeWithoutSpread = t.clone(path.node);
           nodeWithoutSpread.right = ref;
           nodes.push(t.expressionStatement(nodeWithoutSpread));
-          nodes.push(t.toStatement(t.assignmentExpression(
-            "=",
-            argument,
-            callExpression
-          )));
+          nodes.push(
+            t.toStatement(
+              t.assignmentExpression("=", argument, callExpression),
+            ),
+          );
 
           if (ref) {
             nodes.push(t.expressionStatement(ref));
@@ -236,9 +251,9 @@ export default function ({ types: t }) {
 
           path.ensureBlock();
 
-          node.body.body.unshift(t.variableDeclaration("var", [
-            t.variableDeclarator(left, temp),
-          ]));
+          node.body.body.unshift(
+            t.variableDeclaration("var", [t.variableDeclarator(left, temp)]),
+          );
 
           return;
         }
@@ -258,7 +273,7 @@ export default function ({ types: t }) {
         node.body.body.unshift(
           t.variableDeclaration(node.left.kind, [
             t.variableDeclarator(pattern, key),
-          ])
+          ]),
         );
       },
       // var a = { ...b, ...c }
@@ -267,8 +282,10 @@ export default function ({ types: t }) {
 
         const useBuiltIns = file.opts.useBuiltIns || false;
         if (typeof useBuiltIns !== "boolean") {
-          throw new Error("transform-object-rest-spread currently only accepts a boolean " +
-            "option for useBuiltIns (defaults to false)");
+          throw new Error(
+            "transform-object-rest-spread currently only accepts a boolean " +
+              "option for useBuiltIns (defaults to false)",
+          );
         }
 
         const args = [];
@@ -295,9 +312,9 @@ export default function ({ types: t }) {
           args.unshift(t.objectExpression([]));
         }
 
-        const helper = useBuiltIns ?
-          t.memberExpression(t.identifier("Object"), t.identifier("assign")) :
-          file.addHelper("extends");
+        const helper = useBuiltIns
+          ? t.memberExpression(t.identifier("Object"), t.identifier("assign"))
+          : file.addHelper("extends");
 
         path.replaceWith(t.callExpression(helper, args));
       },
diff --git a/packages/babel-plugin-transform-object-set-prototype-of-to-assign/src/index.js b/packages/babel-plugin-transform-object-set-prototype-of-to-assign/src/index.js
index 9f3d99c884..e1a9529c7c 100644
--- a/packages/babel-plugin-transform-object-set-prototype-of-to-assign/src/index.js
+++ b/packages/babel-plugin-transform-object-set-prototype-of-to-assign/src/index.js
@@ -1,4 +1,4 @@
-export default function () {
+export default function() {
   return {
     visitor: {
       CallExpression(path, file) {
diff --git a/packages/babel-plugin-transform-optional-chaining/src/index.js b/packages/babel-plugin-transform-optional-chaining/src/index.js
index a3db104e61..f1a2cfd394 100644
--- a/packages/babel-plugin-transform-optional-chaining/src/index.js
+++ b/packages/babel-plugin-transform-optional-chaining/src/index.js
@@ -1,13 +1,17 @@
 import syntaxOptionalChaining from "babel-plugin-syntax-optional-chaining";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function optional(path, replacementPath, loose = false) {
     const { scope } = path;
     const optionals = [];
     const nil = scope.buildUndefinedNode();
 
     let objectPath = path;
-    while (objectPath.isMemberExpression() || objectPath.isCallExpression() || objectPath.isNewExpression()) {
+    while (
+      objectPath.isMemberExpression() ||
+      objectPath.isCallExpression() ||
+      objectPath.isNewExpression()
+    ) {
       const { node } = objectPath;
       if (node.optional) {
         optionals.push(node);
@@ -25,7 +29,8 @@ export default function ({ types: t }) {
       node.optional = false;
 
       const isCall = t.isCallExpression(node);
-      const replaceKey = isCall || t.isNewExpression(node) ? "callee" : "object";
+      const replaceKey =
+        isCall || t.isNewExpression(node) ? "callee" : "object";
       const chain = node[replaceKey];
 
       let ref;
@@ -67,18 +72,20 @@ export default function ({ types: t }) {
         }
       }
 
-      replacementPath.replaceWith(t.conditionalExpression(
-        t.binaryExpression("==", check, t.nullLiteral()),
-        nil,
-        replacementPath.node
-      ));
+      replacementPath.replaceWith(
+        t.conditionalExpression(
+          t.binaryExpression("==", check, t.nullLiteral()),
+          nil,
+          replacementPath.node,
+        ),
+      );
 
       replacementPath = replacementPath.get("alternate");
     }
   }
 
   function findReplacementPath(path) {
-    return path.find((path) => {
+    return path.find(path => {
       const { parentPath } = path;
 
       if (path.key == "left" && parentPath.isAssignmentExpression()) {
@@ -87,13 +94,19 @@ export default function ({ types: t }) {
       if (path.key == "object" && parentPath.isMemberExpression()) {
         return false;
       }
-      if (path.key == "callee" && (parentPath.isCallExpression() || parentPath.isNewExpression())) {
+      if (
+        path.key == "callee" &&
+        (parentPath.isCallExpression() || parentPath.isNewExpression())
+      ) {
         return false;
       }
       if (path.key == "argument" && parentPath.isUpdateExpression()) {
         return false;
       }
-      if (path.key == "argument" && parentPath.isUnaryExpression({ operator: "delete" })) {
+      if (
+        path.key == "argument" &&
+        parentPath.isUnaryExpression({ operator: "delete" })
+      ) {
         return false;
       }
 
diff --git a/packages/babel-plugin-transform-proto-to-assign/src/index.js b/packages/babel-plugin-transform-proto-to-assign/src/index.js
index 83230a6ae4..302f031cec 100644
--- a/packages/babel-plugin-transform-proto-to-assign/src/index.js
+++ b/packages/babel-plugin-transform-proto-to-assign/src/index.js
@@ -1,18 +1,22 @@
 import pull from "lodash/pull";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function isProtoKey(node) {
     return t.isLiteral(t.toComputedKey(node, node.key), { value: "__proto__" });
   }
 
   function isProtoAssignmentExpression(node) {
     const left = node.left;
-    return t.isMemberExpression(left) &&
-      t.isLiteral(t.toComputedKey(left, left.property), { value: "__proto__" });
+    return (
+      t.isMemberExpression(left) &&
+      t.isLiteral(t.toComputedKey(left, left.property), { value: "__proto__" })
+    );
   }
 
   function buildDefaultsCallExpression(expr, ref, file) {
-    return t.expressionStatement(t.callExpression(file.addHelper("defaults"), [ref, expr.right]));
+    return t.expressionStatement(
+      t.callExpression(file.addHelper("defaults"), [ref, expr.right]),
+    );
   }
 
   return {
@@ -24,7 +28,11 @@ export default function ({ types: t }) {
         const left = path.node.left.object;
         const temp = path.scope.maybeGenerateMemoised(left);
 
-        if (temp) nodes.push(t.expressionStatement(t.assignmentExpression("=", temp, left)));
+        if (temp) {
+          nodes.push(
+            t.expressionStatement(t.assignmentExpression("=", temp, left)),
+          );
+        }
         nodes.push(buildDefaultsCallExpression(path.node, temp || left, file));
         if (temp) nodes.push(temp);
 
@@ -36,7 +44,9 @@ export default function ({ types: t }) {
         if (!t.isAssignmentExpression(expr, { operator: "=" })) return;
 
         if (isProtoAssignmentExpression(expr)) {
-          path.replaceWith(buildDefaultsCallExpression(expr, expr.left.object, file));
+          path.replaceWith(
+            buildDefaultsCallExpression(expr, expr.left.object, file),
+          );
         }
       },
 
diff --git a/packages/babel-plugin-transform-react-constant-elements/src/index.js b/packages/babel-plugin-transform-react-constant-elements/src/index.js
index 5b2b18fcc9..92a839a2e1 100644
--- a/packages/babel-plugin-transform-react-constant-elements/src/index.js
+++ b/packages/babel-plugin-transform-react-constant-elements/src/index.js
@@ -1,4 +1,4 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   const immutabilityVisitor = {
     enter(path, state) {
       const stop = () => {
@@ -12,12 +12,19 @@ export default function ({ types: t }) {
       }
 
       // Elements with refs are not safe to hoist.
-      if (path.isJSXIdentifier({ name: "ref" }) && path.parentPath.isJSXAttribute({ name: path.node })) {
+      if (
+        path.isJSXIdentifier({ name: "ref" }) &&
+        path.parentPath.isJSXAttribute({ name: path.node })
+      ) {
         return stop();
       }
 
       // Ignore identifiers & JSX expressions.
-      if (path.isJSXIdentifier() || path.isIdentifier() || path.isJSXMemberExpression()) {
+      if (
+        path.isJSXIdentifier() ||
+        path.isIdentifier() ||
+        path.isJSXMemberExpression()
+      ) {
         return;
       }
 
@@ -31,7 +38,9 @@ export default function ({ types: t }) {
           if (expressionResult.confident) {
             // We know the result; check its mutability.
             const { value } = expressionResult;
-            const isMutable = (value && typeof value === "object") || (typeof value === "function");
+            const isMutable =
+              (value && typeof value === "object") ||
+              typeof value === "function";
             if (!isMutable) {
               // It evaluated to an immutable value, so we can hoist it.
               return;
diff --git a/packages/babel-plugin-transform-react-display-name/src/index.js b/packages/babel-plugin-transform-react-display-name/src/index.js
index 5558177b01..6b5a0b5f90 100644
--- a/packages/babel-plugin-transform-react-display-name/src/index.js
+++ b/packages/babel-plugin-transform-react-display-name/src/index.js
@@ -1,6 +1,6 @@
 import path from "path";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function addDisplayName(id, call) {
     const props = call.arguments[0].properties;
     let safe = true;
@@ -15,12 +15,16 @@ export default function ({ types: t }) {
     }
 
     if (safe) {
-      props.unshift(t.objectProperty(t.identifier("displayName"), t.stringLiteral(id)));
+      props.unshift(
+        t.objectProperty(t.identifier("displayName"), t.stringLiteral(id)),
+      );
     }
   }
 
-  const isCreateClassCallExpression = t.buildMatchMemberExpression("React.createClass");
-  const isCreateClassAddon = (callee) => callee.name === "createReactClass";
+  const isCreateClassCallExpression = t.buildMatchMemberExpression(
+    "React.createClass",
+  );
+  const isCreateClassAddon = callee => callee.name === "createReactClass";
 
   function isCreateClass(node) {
     if (!node || !t.isCallExpression(node)) return false;
@@ -29,7 +33,9 @@ export default function ({ types: t }) {
     if (
       !isCreateClassCallExpression(node.callee) &&
       !isCreateClassAddon(node.callee)
-    ) return false;
+    ) {
+      return false;
+    }
 
     // no call arguments
     const args = node.arguments;
@@ -46,7 +52,10 @@ export default function ({ types: t }) {
     visitor: {
       ExportDefaultDeclaration({ node }, state) {
         if (isCreateClass(node.declaration)) {
-          let displayName = path.basename(state.file.opts.filename, path.extname(state.file.opts.filename));
+          let displayName = path.basename(
+            state.file.opts.filename,
+            path.extname(state.file.opts.filename),
+          );
 
           // ./{module name}/index.js
           if (displayName === "index") {
@@ -64,7 +73,7 @@ export default function ({ types: t }) {
         let id;
 
         // crawl up the ancestry looking for possible candidates for displayName inference
-        path.find(function (path) {
+        path.find(function(path) {
           if (path.isAssignmentExpression()) {
             id = path.node.left;
           } else if (path.isObjectProperty()) {
diff --git a/packages/babel-plugin-transform-react-inline-elements/src/index.js b/packages/babel-plugin-transform-react-inline-elements/src/index.js
index 9af3146ec7..d920366575 100644
--- a/packages/babel-plugin-transform-react-inline-elements/src/index.js
+++ b/packages/babel-plugin-transform-react-inline-elements/src/index.js
@@ -1,4 +1,4 @@
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function hasRefOrSpread(attrs) {
     for (let i = 0; i < attrs.length; i++) {
       const attr = attrs[i];
@@ -9,7 +9,9 @@ export default function ({ types: t }) {
   }
 
   function isJSXAttributeOfName(attr, name) {
-    return t.isJSXAttribute(attr) && t.isJSXIdentifier(attr.name, { name: name });
+    return (
+      t.isJSXAttribute(attr) && t.isJSXIdentifier(attr.name, { name: name })
+    );
   }
 
   function getAttributeValue(attr) {
@@ -47,7 +49,9 @@ export default function ({ types: t }) {
             key = getAttributeValue(attr);
           } else {
             const name = attr.name.name;
-            const propertyKey = t.isValidIdentifier(name) ? t.identifier(name) : t.stringLiteral(name);
+            const propertyKey = t.isValidIdentifier(name)
+              ? t.identifier(name)
+              : t.stringLiteral(name);
             pushProp(props.properties, propertyKey, getAttributeValue(attr));
           }
         }
@@ -57,7 +61,7 @@ export default function ({ types: t }) {
           const children = t.react.buildChildren(node);
           args.push(
             key || t.unaryExpression("void", t.numericLiteral(0), true),
-            ...children
+            ...children,
           );
         }
 
diff --git a/packages/babel-plugin-transform-react-jsx-compat/src/index.js b/packages/babel-plugin-transform-react-jsx-compat/src/index.js
index 7fa6b05edc..090063762e 100644
--- a/packages/babel-plugin-transform-react-jsx-compat/src/index.js
+++ b/packages/babel-plugin-transform-react-jsx-compat/src/index.js
@@ -1,6 +1,6 @@
 import helper from "babel-helper-builder-react-jsx";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   return {
     manipulateOptions(opts, parserOpts) {
       parserOpts.plugins.push("jsx");
@@ -17,9 +17,9 @@ export default function ({ types: t }) {
             t.memberExpression(
               t.memberExpression(t.identifier("React"), t.identifier("DOM")),
               state.tagExpr,
-              t.isLiteral(state.tagExpr)
+              t.isLiteral(state.tagExpr),
             ),
-            state.args
+            state.args,
           );
         }
       },
diff --git a/packages/babel-plugin-transform-react-jsx-self/src/index.js b/packages/babel-plugin-transform-react-jsx-self/src/index.js
index 089d1c1775..df09aeb26e 100644
--- a/packages/babel-plugin-transform-react-jsx-self/src/index.js
+++ b/packages/babel-plugin-transform-react-jsx-self/src/index.js
@@ -14,7 +14,7 @@
 
 const TRACE_ID = "__self";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   const visitor = {
     JSXOpeningElement({ node }) {
       const id = t.jSXIdentifier(TRACE_ID);
diff --git a/packages/babel-plugin-transform-react-jsx-source/src/index.js b/packages/babel-plugin-transform-react-jsx-source/src/index.js
index 3750d15448..ee3f8813e5 100644
--- a/packages/babel-plugin-transform-react-jsx-source/src/index.js
+++ b/packages/babel-plugin-transform-react-jsx-source/src/index.js
@@ -1,5 +1,4 @@
-
- /**
+/**
  * This adds {fileName, lineNumber} annotations to React component definitions
  * and to jsx tag literals.
  *
@@ -14,15 +13,21 @@
  * <sometag __source={{fileName: __jsxFileName, lineNumber: 10}}/>
  */
 
-
 const TRACE_ID = "__source";
 const FILE_NAME_VAR = "_jsxFileName";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function makeTrace(fileNameIdentifier, lineNumber) {
-    const fileLineLiteral = lineNumber != null ? t.numericLiteral(lineNumber) : t.nullLiteral();
-    const fileNameProperty = t.objectProperty(t.identifier("fileName"), fileNameIdentifier);
-    const lineNumberProperty = t.objectProperty(t.identifier("lineNumber"), fileLineLiteral);
+    const fileLineLiteral =
+      lineNumber != null ? t.numericLiteral(lineNumber) : t.nullLiteral();
+    const fileNameProperty = t.objectProperty(
+      t.identifier("fileName"),
+      fileNameIdentifier,
+    );
+    const lineNumberProperty = t.objectProperty(
+      t.identifier("lineNumber"),
+      fileLineLiteral,
+    );
     return t.objectExpression([fileNameProperty, lineNumberProperty]);
   }
 
@@ -47,8 +52,13 @@ export default function ({ types: t }) {
       if (!state.fileNameIdentifier) {
         const fileName = state.file.opts.filename;
 
-        const fileNameIdentifier = path.scope.generateUidIdentifier(FILE_NAME_VAR);
-        path.hub.file.scope.push({ id: fileNameIdentifier, init: t.stringLiteral(fileName) });
+        const fileNameIdentifier = path.scope.generateUidIdentifier(
+          FILE_NAME_VAR,
+        );
+        path.hub.file.scope.push({
+          id: fileNameIdentifier,
+          init: t.stringLiteral(fileName),
+        });
         state.fileNameIdentifier = fileNameIdentifier;
       }
 
diff --git a/packages/babel-plugin-transform-react-jsx/src/index.js b/packages/babel-plugin-transform-react-jsx/src/index.js
index 0c3df28ebc..5b119cb6f6 100644
--- a/packages/babel-plugin-transform-react-jsx/src/index.js
+++ b/packages/babel-plugin-transform-react-jsx/src/index.js
@@ -1,7 +1,7 @@
 import jsx from "babel-plugin-syntax-jsx";
 import helper from "babel-helper-builder-react-jsx";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   const JSX_ANNOTATION_REGEX = /\*?\s*@jsx\s+([^\s]+)/;
 
   const visitor = helper({
@@ -20,7 +20,7 @@ export default function ({ types: t }) {
     },
   });
 
-  visitor.Program = function (path, state) {
+  visitor.Program = function(path, state) {
     const { file } = state;
     let id = state.opts.pragma || "React.createElement";
 
@@ -29,19 +29,21 @@ export default function ({ types: t }) {
       if (matches) {
         id = matches[1];
         if (id === "React.DOM") {
-          throw file.buildCodeFrameError(comment,
-            "The @jsx React.DOM pragma has been deprecated as of React 0.12");
+          throw file.buildCodeFrameError(
+            comment,
+            "The @jsx React.DOM pragma has been deprecated as of React 0.12",
+          );
         } else {
           break;
         }
       }
     }
 
-    state.set(
-      "jsxIdentifier",
-      () => id.split(".").map((name) => t.identifier(name)).reduce(
-        (object, property) => t.memberExpression(object, property)
-      )
+    state.set("jsxIdentifier", () =>
+      id
+        .split(".")
+        .map(name => t.identifier(name))
+        .reduce((object, property) => t.memberExpression(object, property)),
     );
   };
 
diff --git a/packages/babel-plugin-transform-runtime/src/index.js b/packages/babel-plugin-transform-runtime/src/index.js
index c9737af8a4..4a7c62fe0b 100644
--- a/packages/babel-plugin-transform-runtime/src/index.js
+++ b/packages/babel-plugin-transform-runtime/src/index.js
@@ -1,6 +1,6 @@
 import definitions from "./definitions";
 
-export default function ({ types: t }) {
+export default function({ types: t }) {
   function getRuntimeModuleName(opts) {
     return opts.moduleName || "babel-runtime";
   }
@@ -16,21 +16,35 @@ export default function ({ types: t }) {
       const moduleName = getRuntimeModuleName(this.opts);
 
       if (this.opts.helpers !== false) {
-        const baseHelpersDir = this.opts.useBuiltIns ? "helpers/builtin" : "helpers";
-        const helpersDir = this.opts.useESModules ? `${baseHelpersDir}/es6` : baseHelpersDir;
-        file.set("helperGenerator", function (name) {
+        const baseHelpersDir = this.opts.useBuiltIns
+          ? "helpers/builtin"
+          : "helpers";
+        const helpersDir = this.opts.useESModules
+          ? `${baseHelpersDir}/es6`
+          : baseHelpersDir;
+        file.set("helperGenerator", function(name) {
           if (HELPER_BLACKLIST.indexOf(name) < 0) {
-            return file.addImport(`${moduleName}/${helpersDir}/${name}`, "default", name);
+            return file.addImport(
+              `${moduleName}/${helpersDir}/${name}`,
+              "default",
+              name,
+            );
           }
         });
       }
 
       if (this.opts.polyfill && this.opts.useBuiltIns) {
-        throw new Error("The polyfill option conflicts with useBuiltIns; use one or the other");
+        throw new Error(
+          "The polyfill option conflicts with useBuiltIns; use one or the other",
+        );
       }
 
-      this.setDynamic("regeneratorIdentifier", function () {
-        return file.addImport(`${moduleName}/regenerator`, "default", "regeneratorRuntime");
+      this.setDynamic("regeneratorIdentifier", function() {
+        return file.addImport(
+          `${moduleName}/regenerator`,
+          "default",
+          "regeneratorRuntime",
+        );
       });
     },
 
@@ -38,7 +52,10 @@ export default function ({ types: t }) {
       ReferencedIdentifier(path, state) {
         const { node, parent, scope } = path;
 
-        if (node.name === "regeneratorRuntime" && state.opts.regenerator !== false) {
+        if (
+          node.name === "regeneratorRuntime" &&
+          state.opts.regenerator !== false
+        ) {
           path.replaceWith(state.get("regeneratorIdentifier"));
           return;
         }
@@ -51,11 +68,13 @@ export default function ({ types: t }) {
 
         // Symbol() -> _core.Symbol(); new Promise -> new _core.Promise
         const moduleName = getRuntimeModuleName(state.opts);
-        path.replaceWith(state.addImport(
-          `${moduleName}/core-js/${definitions.builtins[node.name]}`,
-          "default",
-          node.name
-        ));
+        path.replaceWith(
+          state.addImport(
+            `${moduleName}/core-js/${definitions.builtins[node.name]}`,
+            "default",
+            node.name,
+          ),
+        );
       },
 
       // arr[Symbol.iterator]() -> _core.$for.getIterator(arr)
@@ -68,17 +87,21 @@ export default function ({ types: t }) {
         const callee = path.node.callee;
         if (!t.isMemberExpression(callee)) return;
         if (!callee.computed) return;
-        if (!path.get("callee.property").matchesPattern("Symbol.iterator")) return;
+        if (!path.get("callee.property").matchesPattern("Symbol.iterator")) {
+          return;
+        }
 
         const moduleName = getRuntimeModuleName(state.opts);
-        path.replaceWith(t.callExpression(
-          state.addImport(
-            `${moduleName}/core-js/get-iterator`,
-            "default",
-            "getIterator"
+        path.replaceWith(
+          t.callExpression(
+            state.addImport(
+              `${moduleName}/core-js/get-iterator`,
+              "default",
+              "getIterator",
+            ),
+            [callee.object],
           ),
-          [callee.object]
-        ));
+        );
       },
 
       // Symbol.iterator in arr -> core.$for.isIterable(arr)
@@ -89,14 +112,16 @@ export default function ({ types: t }) {
         if (!path.get("left").matchesPattern("Symbol.iterator")) return;
 
         const moduleName = getRuntimeModuleName(state.opts);
-        path.replaceWith(t.callExpression(
-          state.addImport(
-            `${moduleName}/core-js/is-iterable`,
-            "default",
-            "isIterable"
+        path.replaceWith(
+          t.callExpression(
+            state.addImport(
+              `${moduleName}/core-js/is-iterable`,
+              "default",
+              "isIterable",
+            ),
+            [path.node.right],
           ),
-          [path.node.right]
-        ));
+        );
       },
 
       // Array.from -> _core.Array.from
@@ -120,17 +145,25 @@ export default function ({ types: t }) {
           if (path.scope.getBindingIdentifier(obj.name)) return;
 
           // special case Object.defineProperty to not use core-js when using string keys
-          if (obj.name === "Object" && prop.name === "defineProperty" && path.parentPath.isCallExpression()) {
+          if (
+            obj.name === "Object" &&
+            prop.name === "defineProperty" &&
+            path.parentPath.isCallExpression()
+          ) {
             const call = path.parentPath.node;
-            if (call.arguments.length === 3 && t.isLiteral(call.arguments[1])) return;
+            if (call.arguments.length === 3 && t.isLiteral(call.arguments[1])) {
+              return;
+            }
           }
 
           const moduleName = getRuntimeModuleName(state.opts);
-          path.replaceWith(state.addImport(
-            `${moduleName}/core-js/${methods[prop.name]}`,
-            "default",
-            `${obj.name}$${prop.name}`
-          ));
+          path.replaceWith(
+            state.addImport(
+              `${moduleName}/core-js/${methods[prop.name]}`,
+              "default",
+              `${obj.name}$${prop.name}`,
+            ),
+          );
         },
 
         exit(path, state) {
@@ -144,15 +177,17 @@ export default function ({ types: t }) {
           if (path.scope.getBindingIdentifier(obj.name)) return;
 
           const moduleName = getRuntimeModuleName(state.opts);
-          path.replaceWith(t.memberExpression(
-            state.addImport(
-              `${moduleName}/core-js/${definitions.builtins[obj.name]}`,
-              "default",
-              obj.name
+          path.replaceWith(
+            t.memberExpression(
+              state.addImport(
+                `${moduleName}/core-js/${definitions.builtins[obj.name]}`,
+                "default",
+                obj.name,
+              ),
+              node.property,
+              node.computed,
             ),
-            node.property,
-            node.computed
-          ));
+          );
         },
       },
     },
diff --git a/packages/babel-plugin-transform-strict-mode/src/index.js b/packages/babel-plugin-transform-strict-mode/src/index.js
index 54b84fad98..756979d79e 100644
--- a/packages/babel-plugin-transform-strict-mode/src/index.js
+++ b/packages/babel-plugin-transform-strict-mode/src/index.js
@@ -1,10 +1,12 @@
 import * as t from "babel-types";
 
-export default function () {
+export default function() {
   return {
     visitor: {
       Program(path, state) {
-        if (state.opts.strict === false || state.opts.strictMode === false) return;
+        if (state.opts.strict === false || state.opts.strictMode === false) {
+          return;
+        }
 
         const { node } = path;
 
@@ -12,7 +14,10 @@ export default function () {
           if (directive.value.value === "use strict") return;
         }
 
-        path.unshiftContainer("directives", t.directive(t.directiveLiteral("use strict")));
+        path.unshiftContainer(
+          "directives",
+          t.directive(t.directiveLiteral("use strict")),
+        );
       },
     },
   };
diff --git a/packages/babel-polyfill/scripts/make-separate-polyfill-files.js b/packages/babel-polyfill/scripts/make-separate-polyfill-files.js
index 464bef4506..657480f1f7 100644
--- a/packages/babel-polyfill/scripts/make-separate-polyfill-files.js
+++ b/packages/babel-polyfill/scripts/make-separate-polyfill-files.js
@@ -10,12 +10,16 @@ function relative(loc) {
 const builtIns = require("babel-preset-env/data/built-ins.json");
 const polyfills = Object.keys(builtIns);
 
-polyfills.concat([
-  "web.timers",
-  "web.immediate",
-  "web.dom.iterable"]
-).forEach((polyfill) => {
-  fs.writeFileSync(relative(`src/core-js/modules/${polyfill}.js`), `require("core-js/modules/${polyfill}");`);
-});
+polyfills
+  .concat(["web.timers", "web.immediate", "web.dom.iterable"])
+  .forEach(polyfill => {
+    fs.writeFileSync(
+      relative(`src/core-js/modules/${polyfill}.js`),
+      `require("core-js/modules/${polyfill}");`,
+    );
+  });
 
-fs.writeFileSync(relative("src/regenerator-runtime/runtime.js"), "require(\"regenerator-runtime/runtime\");");
+fs.writeFileSync(
+  relative("src/regenerator-runtime/runtime.js"),
+  'require("regenerator-runtime/runtime");',
+);
diff --git a/packages/babel-polyfill/scripts/postpublish.js b/packages/babel-polyfill/scripts/postpublish.js
index c66b9e775f..57a59218c8 100644
--- a/packages/babel-polyfill/scripts/postpublish.js
+++ b/packages/babel-polyfill/scripts/postpublish.js
@@ -6,4 +6,3 @@ const path = require("path");
 try {
   fs.unlinkSync(path.join(__dirname, "../browser.js"));
 } catch (err) {}
-
diff --git a/packages/babel-polyfill/scripts/prepublish.js b/packages/babel-polyfill/scripts/prepublish.js
index b2e14976e9..ff29b6ae74 100644
--- a/packages/babel-polyfill/scripts/prepublish.js
+++ b/packages/babel-polyfill/scripts/prepublish.js
@@ -7,4 +7,7 @@ function relative(loc) {
   return path.join(__dirname, "..", loc);
 }
 
-fs.writeFileSync(relative("browser.js"), fs.readFileSync(relative("dist/polyfill.min.js")));
+fs.writeFileSync(
+  relative("browser.js"),
+  fs.readFileSync(relative("dist/polyfill.min.js")),
+);
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.array.copy-within.js b/packages/babel-polyfill/src/core-js/modules/es6.array.copy-within.js
index 6cbfcb037d..5a4f4c7c34 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.array.copy-within.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.array.copy-within.js
@@ -1 +1 @@
-require("core-js/modules/es6.array.copy-within");
\ No newline at end of file
+require("core-js/modules/es6.array.copy-within");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.array.fill.js b/packages/babel-polyfill/src/core-js/modules/es6.array.fill.js
index 93c1bace02..8049260fd5 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.array.fill.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.array.fill.js
@@ -1 +1 @@
-require("core-js/modules/es6.array.fill");
\ No newline at end of file
+require("core-js/modules/es6.array.fill");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.array.find-index.js b/packages/babel-polyfill/src/core-js/modules/es6.array.find-index.js
index 2e585e27a9..6b9b762374 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.array.find-index.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.array.find-index.js
@@ -1 +1 @@
-require("core-js/modules/es6.array.find-index");
\ No newline at end of file
+require("core-js/modules/es6.array.find-index");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.array.find.js b/packages/babel-polyfill/src/core-js/modules/es6.array.find.js
index ad74b560b2..7dfc636a90 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.array.find.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.array.find.js
@@ -1 +1 @@
-require("core-js/modules/es6.array.find");
\ No newline at end of file
+require("core-js/modules/es6.array.find");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.array.from.js b/packages/babel-polyfill/src/core-js/modules/es6.array.from.js
index 713bc6f3f3..753a7cc87a 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.array.from.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.array.from.js
@@ -1 +1 @@
-require("core-js/modules/es6.array.from");
\ No newline at end of file
+require("core-js/modules/es6.array.from");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.array.iterator.js b/packages/babel-polyfill/src/core-js/modules/es6.array.iterator.js
index 769cfa8952..d30f3dbfb1 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.array.iterator.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.array.iterator.js
@@ -1 +1 @@
-require("core-js/modules/es6.array.iterator");
\ No newline at end of file
+require("core-js/modules/es6.array.iterator");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.array.of.js b/packages/babel-polyfill/src/core-js/modules/es6.array.of.js
index 0739a726d3..2f3e85a1f0 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.array.of.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.array.of.js
@@ -1 +1 @@
-require("core-js/modules/es6.array.of");
\ No newline at end of file
+require("core-js/modules/es6.array.of");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.function.name.js b/packages/babel-polyfill/src/core-js/modules/es6.function.name.js
index c010c8cc84..7ac457d021 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.function.name.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.function.name.js
@@ -1 +1 @@
-require("core-js/modules/es6.function.name");
\ No newline at end of file
+require("core-js/modules/es6.function.name");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.map.js b/packages/babel-polyfill/src/core-js/modules/es6.map.js
index 611f7b938b..60f8ff9d82 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.map.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.map.js
@@ -1 +1 @@
-require("core-js/modules/es6.map");
\ No newline at end of file
+require("core-js/modules/es6.map");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.acosh.js b/packages/babel-polyfill/src/core-js/modules/es6.math.acosh.js
index b6319db618..e5d1d8731b 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.acosh.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.acosh.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.acosh");
\ No newline at end of file
+require("core-js/modules/es6.math.acosh");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.asinh.js b/packages/babel-polyfill/src/core-js/modules/es6.math.asinh.js
index 247ea4731a..a36f04e8d2 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.asinh.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.asinh.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.asinh");
\ No newline at end of file
+require("core-js/modules/es6.math.asinh");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.atanh.js b/packages/babel-polyfill/src/core-js/modules/es6.math.atanh.js
index 000dc4edad..4df4528695 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.atanh.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.atanh.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.atanh");
\ No newline at end of file
+require("core-js/modules/es6.math.atanh");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.cbrt.js b/packages/babel-polyfill/src/core-js/modules/es6.math.cbrt.js
index ad709e74ee..7e4458d4ac 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.cbrt.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.cbrt.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.cbrt");
\ No newline at end of file
+require("core-js/modules/es6.math.cbrt");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.clz32.js b/packages/babel-polyfill/src/core-js/modules/es6.math.clz32.js
index 282410f365..37f4313c4e 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.clz32.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.clz32.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.clz32");
\ No newline at end of file
+require("core-js/modules/es6.math.clz32");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.cosh.js b/packages/babel-polyfill/src/core-js/modules/es6.math.cosh.js
index 30d7ca248e..b81d07ba4d 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.cosh.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.cosh.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.cosh");
\ No newline at end of file
+require("core-js/modules/es6.math.cosh");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.expm1.js b/packages/babel-polyfill/src/core-js/modules/es6.math.expm1.js
index 6dbdf55b05..c4605327a4 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.expm1.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.expm1.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.expm1");
\ No newline at end of file
+require("core-js/modules/es6.math.expm1");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.fround.js b/packages/babel-polyfill/src/core-js/modules/es6.math.fround.js
index d4186769bd..f5e7f8cb17 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.fround.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.fround.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.fround");
\ No newline at end of file
+require("core-js/modules/es6.math.fround");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.hypot.js b/packages/babel-polyfill/src/core-js/modules/es6.math.hypot.js
index 757ac9c561..6775d98ff6 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.hypot.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.hypot.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.hypot");
\ No newline at end of file
+require("core-js/modules/es6.math.hypot");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.imul.js b/packages/babel-polyfill/src/core-js/modules/es6.math.imul.js
index 03935a748d..5902fefe75 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.imul.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.imul.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.imul");
\ No newline at end of file
+require("core-js/modules/es6.math.imul");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.log10.js b/packages/babel-polyfill/src/core-js/modules/es6.math.log10.js
index c4954b3090..4c264b1fb1 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.log10.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.log10.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.log10");
\ No newline at end of file
+require("core-js/modules/es6.math.log10");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.log1p.js b/packages/babel-polyfill/src/core-js/modules/es6.math.log1p.js
index 2f3f770b9d..bccf43543f 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.log1p.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.log1p.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.log1p");
\ No newline at end of file
+require("core-js/modules/es6.math.log1p");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.log2.js b/packages/babel-polyfill/src/core-js/modules/es6.math.log2.js
index 39db6904db..3a37f3aa24 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.log2.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.log2.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.log2");
\ No newline at end of file
+require("core-js/modules/es6.math.log2");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.sign.js b/packages/babel-polyfill/src/core-js/modules/es6.math.sign.js
index d20dc5c1ba..7c81884f73 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.sign.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.sign.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.sign");
\ No newline at end of file
+require("core-js/modules/es6.math.sign");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.sinh.js b/packages/babel-polyfill/src/core-js/modules/es6.math.sinh.js
index ffa5c812f4..3904fad714 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.sinh.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.sinh.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.sinh");
\ No newline at end of file
+require("core-js/modules/es6.math.sinh");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.tanh.js b/packages/babel-polyfill/src/core-js/modules/es6.math.tanh.js
index 016e50bba2..1269addd9d 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.tanh.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.tanh.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.tanh");
\ No newline at end of file
+require("core-js/modules/es6.math.tanh");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.math.trunc.js b/packages/babel-polyfill/src/core-js/modules/es6.math.trunc.js
index e1a6793cb6..632a15f7f7 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.math.trunc.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.math.trunc.js
@@ -1 +1 @@
-require("core-js/modules/es6.math.trunc");
\ No newline at end of file
+require("core-js/modules/es6.math.trunc");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.number.epsilon.js b/packages/babel-polyfill/src/core-js/modules/es6.number.epsilon.js
index 881edc14fd..e75615421e 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.number.epsilon.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.number.epsilon.js
@@ -1 +1 @@
-require("core-js/modules/es6.number.epsilon");
\ No newline at end of file
+require("core-js/modules/es6.number.epsilon");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.number.is-finite.js b/packages/babel-polyfill/src/core-js/modules/es6.number.is-finite.js
index 884c54d706..8180d872cc 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.number.is-finite.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.number.is-finite.js
@@ -1 +1 @@
-require("core-js/modules/es6.number.is-finite");
\ No newline at end of file
+require("core-js/modules/es6.number.is-finite");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.number.is-integer.js b/packages/babel-polyfill/src/core-js/modules/es6.number.is-integer.js
index 6c4ff96284..d35b6f1b8b 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.number.is-integer.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.number.is-integer.js
@@ -1 +1 @@
-require("core-js/modules/es6.number.is-integer");
\ No newline at end of file
+require("core-js/modules/es6.number.is-integer");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.number.is-nan.js b/packages/babel-polyfill/src/core-js/modules/es6.number.is-nan.js
index 6f01f0ad79..03a95c80d2 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.number.is-nan.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.number.is-nan.js
@@ -1 +1 @@
-require("core-js/modules/es6.number.is-nan");
\ No newline at end of file
+require("core-js/modules/es6.number.is-nan");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.number.is-safe-integer.js b/packages/babel-polyfill/src/core-js/modules/es6.number.is-safe-integer.js
index ed73a3ad58..9563579c51 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.number.is-safe-integer.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.number.is-safe-integer.js
@@ -1 +1 @@
-require("core-js/modules/es6.number.is-safe-integer");
\ No newline at end of file
+require("core-js/modules/es6.number.is-safe-integer");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.number.max-safe-integer.js b/packages/babel-polyfill/src/core-js/modules/es6.number.max-safe-integer.js
index bec80a10ff..ca09c56fe7 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.number.max-safe-integer.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.number.max-safe-integer.js
@@ -1 +1 @@
-require("core-js/modules/es6.number.max-safe-integer");
\ No newline at end of file
+require("core-js/modules/es6.number.max-safe-integer");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.number.min-safe-integer.js b/packages/babel-polyfill/src/core-js/modules/es6.number.min-safe-integer.js
index 68e19a98e0..787cc54987 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.number.min-safe-integer.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.number.min-safe-integer.js
@@ -1 +1 @@
-require("core-js/modules/es6.number.min-safe-integer");
\ No newline at end of file
+require("core-js/modules/es6.number.min-safe-integer");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.object.assign.js b/packages/babel-polyfill/src/core-js/modules/es6.object.assign.js
index 661a073a4a..6028b3c392 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.object.assign.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.object.assign.js
@@ -1 +1 @@
-require("core-js/modules/es6.object.assign");
\ No newline at end of file
+require("core-js/modules/es6.object.assign");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.object.is.js b/packages/babel-polyfill/src/core-js/modules/es6.object.is.js
index 9d415fe1f6..d5247f610b 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.object.is.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.object.is.js
@@ -1 +1 @@
-require("core-js/modules/es6.object.is");
\ No newline at end of file
+require("core-js/modules/es6.object.is");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.object.set-prototype-of.js b/packages/babel-polyfill/src/core-js/modules/es6.object.set-prototype-of.js
index f1a87cc5e4..1d7cb1ae2c 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.object.set-prototype-of.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.object.set-prototype-of.js
@@ -1 +1 @@
-require("core-js/modules/es6.object.set-prototype-of");
\ No newline at end of file
+require("core-js/modules/es6.object.set-prototype-of");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.promise.js b/packages/babel-polyfill/src/core-js/modules/es6.promise.js
index e73b4811eb..9bb31e94b9 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.promise.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.promise.js
@@ -1 +1 @@
-require("core-js/modules/es6.promise");
\ No newline at end of file
+require("core-js/modules/es6.promise");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.apply.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.apply.js
index a0957fc3e0..b0e30a57f6 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.apply.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.apply.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.apply");
\ No newline at end of file
+require("core-js/modules/es6.reflect.apply");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.construct.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.construct.js
index f4995e7ebb..fe08b868b7 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.construct.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.construct.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.construct");
\ No newline at end of file
+require("core-js/modules/es6.reflect.construct");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.define-property.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.define-property.js
index f29f414753..6e589b3b0b 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.define-property.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.define-property.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.define-property");
\ No newline at end of file
+require("core-js/modules/es6.reflect.define-property");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.delete-property.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.delete-property.js
index 54dee9ab22..0642b580aa 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.delete-property.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.delete-property.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.delete-property");
\ No newline at end of file
+require("core-js/modules/es6.reflect.delete-property");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.get-own-property-descriptor.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.get-own-property-descriptor.js
index 45dad4efff..7785fe5d6b 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.get-own-property-descriptor.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.get-own-property-descriptor.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.get-own-property-descriptor");
\ No newline at end of file
+require("core-js/modules/es6.reflect.get-own-property-descriptor");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.get-prototype-of.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.get-prototype-of.js
index 10f36336a6..da50971e67 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.get-prototype-of.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.get-prototype-of.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.get-prototype-of");
\ No newline at end of file
+require("core-js/modules/es6.reflect.get-prototype-of");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.get.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.get.js
index 6a45954823..e3e25b521d 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.get.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.get.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.get");
\ No newline at end of file
+require("core-js/modules/es6.reflect.get");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.has.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.has.js
index e0ab03b53d..517da7db2f 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.has.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.has.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.has");
\ No newline at end of file
+require("core-js/modules/es6.reflect.has");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.is-extensible.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.is-extensible.js
index c9880c56d9..6a5c688ed2 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.is-extensible.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.is-extensible.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.is-extensible");
\ No newline at end of file
+require("core-js/modules/es6.reflect.is-extensible");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.own-keys.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.own-keys.js
index da3dc88341..3ee1dfb62c 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.own-keys.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.own-keys.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.own-keys");
\ No newline at end of file
+require("core-js/modules/es6.reflect.own-keys");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.prevent-extensions.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.prevent-extensions.js
index cba05c087c..3e30b05c3e 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.prevent-extensions.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.prevent-extensions.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.prevent-extensions");
\ No newline at end of file
+require("core-js/modules/es6.reflect.prevent-extensions");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.set-prototype-of.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.set-prototype-of.js
index cc4c47b989..99ac2cf002 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.set-prototype-of.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.set-prototype-of.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.set-prototype-of");
\ No newline at end of file
+require("core-js/modules/es6.reflect.set-prototype-of");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.reflect.set.js b/packages/babel-polyfill/src/core-js/modules/es6.reflect.set.js
index f5ba65ff07..0fc687bbc1 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.reflect.set.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.reflect.set.js
@@ -1 +1 @@
-require("core-js/modules/es6.reflect.set");
\ No newline at end of file
+require("core-js/modules/es6.reflect.set");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.regexp.flags.js b/packages/babel-polyfill/src/core-js/modules/es6.regexp.flags.js
index b41c560498..a01638b419 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.regexp.flags.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.regexp.flags.js
@@ -1 +1 @@
-require("core-js/modules/es6.regexp.flags");
\ No newline at end of file
+require("core-js/modules/es6.regexp.flags");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.regexp.match.js b/packages/babel-polyfill/src/core-js/modules/es6.regexp.match.js
index d82b695964..e0a03de173 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.regexp.match.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.regexp.match.js
@@ -1 +1 @@
-require("core-js/modules/es6.regexp.match");
\ No newline at end of file
+require("core-js/modules/es6.regexp.match");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.regexp.replace.js b/packages/babel-polyfill/src/core-js/modules/es6.regexp.replace.js
index 68b6dc5298..808439aff6 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.regexp.replace.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.regexp.replace.js
@@ -1 +1 @@
-require("core-js/modules/es6.regexp.replace");
\ No newline at end of file
+require("core-js/modules/es6.regexp.replace");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.regexp.search.js b/packages/babel-polyfill/src/core-js/modules/es6.regexp.search.js
index bd8c418ea0..295f515d30 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.regexp.search.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.regexp.search.js
@@ -1 +1 @@
-require("core-js/modules/es6.regexp.search");
\ No newline at end of file
+require("core-js/modules/es6.regexp.search");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.regexp.split.js b/packages/babel-polyfill/src/core-js/modules/es6.regexp.split.js
index 9acdbc7b76..fce46adc6a 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.regexp.split.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.regexp.split.js
@@ -1 +1 @@
-require("core-js/modules/es6.regexp.split");
\ No newline at end of file
+require("core-js/modules/es6.regexp.split");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.set.js b/packages/babel-polyfill/src/core-js/modules/es6.set.js
index f14ca09169..c0a168b4f5 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.set.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.set.js
@@ -1 +1 @@
-require("core-js/modules/es6.set");
\ No newline at end of file
+require("core-js/modules/es6.set");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.string.code-point-at.js b/packages/babel-polyfill/src/core-js/modules/es6.string.code-point-at.js
index 68e164e71a..36ab5b1dc0 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.string.code-point-at.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.string.code-point-at.js
@@ -1 +1 @@
-require("core-js/modules/es6.string.code-point-at");
\ No newline at end of file
+require("core-js/modules/es6.string.code-point-at");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.string.ends-with.js b/packages/babel-polyfill/src/core-js/modules/es6.string.ends-with.js
index b5c4e225d1..699b33c91b 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.string.ends-with.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.string.ends-with.js
@@ -1 +1 @@
-require("core-js/modules/es6.string.ends-with");
\ No newline at end of file
+require("core-js/modules/es6.string.ends-with");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.string.from-code-point.js b/packages/babel-polyfill/src/core-js/modules/es6.string.from-code-point.js
index fa25b82dc0..e333f6bd12 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.string.from-code-point.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.string.from-code-point.js
@@ -1 +1 @@
-require("core-js/modules/es6.string.from-code-point");
\ No newline at end of file
+require("core-js/modules/es6.string.from-code-point");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.string.includes.js b/packages/babel-polyfill/src/core-js/modules/es6.string.includes.js
index 6ba52e9b5e..d18d548db6 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.string.includes.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.string.includes.js
@@ -1 +1 @@
-require("core-js/modules/es6.string.includes");
\ No newline at end of file
+require("core-js/modules/es6.string.includes");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.string.raw.js b/packages/babel-polyfill/src/core-js/modules/es6.string.raw.js
index b3a7d7669a..2aff0ad937 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.string.raw.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.string.raw.js
@@ -1 +1 @@
-require("core-js/modules/es6.string.raw");
\ No newline at end of file
+require("core-js/modules/es6.string.raw");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.string.repeat.js b/packages/babel-polyfill/src/core-js/modules/es6.string.repeat.js
index baebf48405..58122e21e5 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.string.repeat.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.string.repeat.js
@@ -1 +1 @@
-require("core-js/modules/es6.string.repeat");
\ No newline at end of file
+require("core-js/modules/es6.string.repeat");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.string.starts-with.js b/packages/babel-polyfill/src/core-js/modules/es6.string.starts-with.js
index 88a39a504c..02298070c1 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.string.starts-with.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.string.starts-with.js
@@ -1 +1 @@
-require("core-js/modules/es6.string.starts-with");
\ No newline at end of file
+require("core-js/modules/es6.string.starts-with");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.symbol.js b/packages/babel-polyfill/src/core-js/modules/es6.symbol.js
index ed68247c21..330d7a34a2 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.symbol.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.symbol.js
@@ -1 +1 @@
-require("core-js/modules/es6.symbol");
\ No newline at end of file
+require("core-js/modules/es6.symbol");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.array-buffer.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.array-buffer.js
index 9f48f04f41..c6856ff5e8 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.array-buffer.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.array-buffer.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.array-buffer");
\ No newline at end of file
+require("core-js/modules/es6.typed.array-buffer");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.data-view.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.data-view.js
index 0ac6537a03..05d2172b8f 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.data-view.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.data-view.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.data-view");
\ No newline at end of file
+require("core-js/modules/es6.typed.data-view");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.float32-array.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.float32-array.js
index 8fa5d2f5e9..41259ae582 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.float32-array.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.float32-array.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.float32-array");
\ No newline at end of file
+require("core-js/modules/es6.typed.float32-array");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.float64-array.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.float64-array.js
index fd5c7acf78..62de5e290a 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.float64-array.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.float64-array.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.float64-array");
\ No newline at end of file
+require("core-js/modules/es6.typed.float64-array");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.int16-array.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.int16-array.js
index d7abf7153f..c479a1019d 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.int16-array.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.int16-array.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.int16-array");
\ No newline at end of file
+require("core-js/modules/es6.typed.int16-array");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.int32-array.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.int32-array.js
index f7f205fd4d..cc118e4014 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.int32-array.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.int32-array.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.int32-array");
\ No newline at end of file
+require("core-js/modules/es6.typed.int32-array");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.int8-array.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.int8-array.js
index 857c9024c9..687fe8e4fc 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.int8-array.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.int8-array.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.int8-array");
\ No newline at end of file
+require("core-js/modules/es6.typed.int8-array");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.uint16-array.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.uint16-array.js
index a3a722beba..845c25afdd 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.uint16-array.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.uint16-array.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.uint16-array");
\ No newline at end of file
+require("core-js/modules/es6.typed.uint16-array");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.uint32-array.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.uint32-array.js
index ec9ec9fecb..e14927a216 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.uint32-array.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.uint32-array.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.uint32-array");
\ No newline at end of file
+require("core-js/modules/es6.typed.uint32-array");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.uint8-array.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.uint8-array.js
index 6ac7328571..96d98bc472 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.uint8-array.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.uint8-array.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.uint8-array");
\ No newline at end of file
+require("core-js/modules/es6.typed.uint8-array");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.typed.uint8-clamped-array.js b/packages/babel-polyfill/src/core-js/modules/es6.typed.uint8-clamped-array.js
index b24a51ffe5..eeff2d8462 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.typed.uint8-clamped-array.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.typed.uint8-clamped-array.js
@@ -1 +1 @@
-require("core-js/modules/es6.typed.uint8-clamped-array");
\ No newline at end of file
+require("core-js/modules/es6.typed.uint8-clamped-array");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.weak-map.js b/packages/babel-polyfill/src/core-js/modules/es6.weak-map.js
index 5a60ca35ff..41223aa9f4 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.weak-map.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.weak-map.js
@@ -1 +1 @@
-require("core-js/modules/es6.weak-map");
\ No newline at end of file
+require("core-js/modules/es6.weak-map");
diff --git a/packages/babel-polyfill/src/core-js/modules/es6.weak-set.js b/packages/babel-polyfill/src/core-js/modules/es6.weak-set.js
index 4038b85f67..646cbe1b5e 100644
--- a/packages/babel-polyfill/src/core-js/modules/es6.weak-set.js
+++ b/packages/babel-polyfill/src/core-js/modules/es6.weak-set.js
@@ -1 +1 @@
-require("core-js/modules/es6.weak-set");
\ No newline at end of file
+require("core-js/modules/es6.weak-set");
diff --git a/packages/babel-polyfill/src/core-js/modules/es7.array.includes.js b/packages/babel-polyfill/src/core-js/modules/es7.array.includes.js
index 45dc5144dc..98ab65bf9b 100644
--- a/packages/babel-polyfill/src/core-js/modules/es7.array.includes.js
+++ b/packages/babel-polyfill/src/core-js/modules/es7.array.includes.js
@@ -1 +1 @@
-require("core-js/modules/es7.array.includes");
\ No newline at end of file
+require("core-js/modules/es7.array.includes");
diff --git a/packages/babel-polyfill/src/core-js/modules/es7.object.entries.js b/packages/babel-polyfill/src/core-js/modules/es7.object.entries.js
index beddd94407..afe0e5f103 100644
--- a/packages/babel-polyfill/src/core-js/modules/es7.object.entries.js
+++ b/packages/babel-polyfill/src/core-js/modules/es7.object.entries.js
@@ -1 +1 @@
-require("core-js/modules/es7.object.entries");
\ No newline at end of file
+require("core-js/modules/es7.object.entries");
diff --git a/packages/babel-polyfill/src/core-js/modules/es7.object.get-own-property-descriptors.js b/packages/babel-polyfill/src/core-js/modules/es7.object.get-own-property-descriptors.js
index 8a75b92f72..d061909cd8 100644
--- a/packages/babel-polyfill/src/core-js/modules/es7.object.get-own-property-descriptors.js
+++ b/packages/babel-polyfill/src/core-js/modules/es7.object.get-own-property-descriptors.js
@@ -1 +1 @@
-require("core-js/modules/es7.object.get-own-property-descriptors");
\ No newline at end of file
+require("core-js/modules/es7.object.get-own-property-descriptors");
diff --git a/packages/babel-polyfill/src/core-js/modules/es7.object.values.js b/packages/babel-polyfill/src/core-js/modules/es7.object.values.js
index 3dc94404d7..cf1e266e81 100644
--- a/packages/babel-polyfill/src/core-js/modules/es7.object.values.js
+++ b/packages/babel-polyfill/src/core-js/modules/es7.object.values.js
@@ -1 +1 @@
-require("core-js/modules/es7.object.values");
\ No newline at end of file
+require("core-js/modules/es7.object.values");
diff --git a/packages/babel-polyfill/src/core-js/modules/es7.string.pad-end.js b/packages/babel-polyfill/src/core-js/modules/es7.string.pad-end.js
index 08896510b4..0bb8dd4cf4 100644
--- a/packages/babel-polyfill/src/core-js/modules/es7.string.pad-end.js
+++ b/packages/babel-polyfill/src/core-js/modules/es7.string.pad-end.js
@@ -1 +1 @@
-require("core-js/modules/es7.string.pad-end");
\ No newline at end of file
+require("core-js/modules/es7.string.pad-end");
diff --git a/packages/babel-polyfill/src/core-js/modules/es7.string.pad-start.js b/packages/babel-polyfill/src/core-js/modules/es7.string.pad-start.js
index d54f216459..09ad55f543 100644
--- a/packages/babel-polyfill/src/core-js/modules/es7.string.pad-start.js
+++ b/packages/babel-polyfill/src/core-js/modules/es7.string.pad-start.js
@@ -1 +1 @@
-require("core-js/modules/es7.string.pad-start");
\ No newline at end of file
+require("core-js/modules/es7.string.pad-start");
diff --git a/packages/babel-polyfill/src/core-js/modules/web.dom.iterable.js b/packages/babel-polyfill/src/core-js/modules/web.dom.iterable.js
index 2f868c5210..c2d74a05c6 100644
--- a/packages/babel-polyfill/src/core-js/modules/web.dom.iterable.js
+++ b/packages/babel-polyfill/src/core-js/modules/web.dom.iterable.js
@@ -1 +1 @@
-require("core-js/modules/web.dom.iterable");
\ No newline at end of file
+require("core-js/modules/web.dom.iterable");
diff --git a/packages/babel-polyfill/src/core-js/modules/web.immediate.js b/packages/babel-polyfill/src/core-js/modules/web.immediate.js
index cba73cdb21..3de1e2c774 100644
--- a/packages/babel-polyfill/src/core-js/modules/web.immediate.js
+++ b/packages/babel-polyfill/src/core-js/modules/web.immediate.js
@@ -1 +1 @@
-require("core-js/modules/web.immediate");
\ No newline at end of file
+require("core-js/modules/web.immediate");
diff --git a/packages/babel-polyfill/src/core-js/modules/web.timers.js b/packages/babel-polyfill/src/core-js/modules/web.timers.js
index 300122af9d..9f86364e98 100644
--- a/packages/babel-polyfill/src/core-js/modules/web.timers.js
+++ b/packages/babel-polyfill/src/core-js/modules/web.timers.js
@@ -1 +1 @@
-require("core-js/modules/web.timers");
\ No newline at end of file
+require("core-js/modules/web.timers");
diff --git a/packages/babel-polyfill/src/regenerator-runtime/runtime.js b/packages/babel-polyfill/src/regenerator-runtime/runtime.js
index cc4883fa4d..c82509c6b8 100644
--- a/packages/babel-polyfill/src/regenerator-runtime/runtime.js
+++ b/packages/babel-polyfill/src/regenerator-runtime/runtime.js
@@ -1 +1 @@
-require("regenerator-runtime/runtime");
\ No newline at end of file
+require("regenerator-runtime/runtime");
diff --git a/packages/babel-preset-es2015/src/index.js b/packages/babel-preset-es2015/src/index.js
index 162854e9c8..f1721c6e13 100644
--- a/packages/babel-preset-es2015/src/index.js
+++ b/packages/babel-preset-es2015/src/index.js
@@ -23,7 +23,7 @@ import transformES2015ModulesAMD from "babel-plugin-transform-es2015-modules-amd
 import transformES2015ModulesUMD from "babel-plugin-transform-es2015-modules-umd";
 import transformRegenerator from "babel-plugin-transform-regenerator";
 
-export default function (context, opts = {}) {
+export default function(context, opts = {}) {
   const moduleTypes = ["commonjs", "amd", "umd", "systemjs"];
   let loose = false;
   let modules = "commonjs";
@@ -35,11 +35,17 @@ export default function (context, opts = {}) {
     if (opts.spec !== undefined) spec = opts.spec;
   }
 
-  if (typeof loose !== "boolean") throw new Error("Preset es2015 'loose' option must be a boolean.");
-  if (typeof spec !== "boolean") throw new Error("Preset es2015 'spec' option must be a boolean.");
+  if (typeof loose !== "boolean") {
+    throw new Error("Preset es2015 'loose' option must be a boolean.");
+  }
+  if (typeof spec !== "boolean") {
+    throw new Error("Preset es2015 'spec' option must be a boolean.");
+  }
   if (modules !== false && moduleTypes.indexOf(modules) === -1) {
-    throw new Error("Preset es2015 'modules' option must be 'false' to indicate no modules\n" +
-      "or a module type which be be one of: 'commonjs' (default), 'amd', 'umd', 'systemjs'");
+    throw new Error(
+      "Preset es2015 'modules' option must be 'false' to indicate no modules\n" +
+        "or a module type which be be one of: 'commonjs' (default), 'amd', 'umd', 'systemjs'",
+    );
   }
 
   // be DRY
diff --git a/packages/babel-preset-es2015/test/index.js b/packages/babel-preset-es2015/test/index.js
index ffb1683dd3..d09abe717f 100644
--- a/packages/babel-preset-es2015/test/index.js
+++ b/packages/babel-preset-es2015/test/index.js
@@ -1,58 +1,57 @@
 import es2015 from "../lib";
 import { expect } from "chai";
 
-describe("es2015 preset", function () {
-
-  it("doesn't throw with no options passed", function () {
-    expect(function () {
+describe("es2015 preset", function() {
+  it("doesn't throw with no options passed", function() {
+    expect(function() {
       es2015(null);
     }).not.to.throw();
   });
 
-  describe("options", function () {
-    describe("loose", function () {
-      it("throws on non-boolean value", function () {
-        expect(function () {
+  describe("options", function() {
+    describe("loose", function() {
+      it("throws on non-boolean value", function() {
+        expect(function() {
           es2015(null, { loose: 1 });
         }).to.throw(/must be a boolean/);
       });
     });
 
-    describe("spec", function () {
-      it("throws on non-boolean value", function () {
-        expect(function () {
+    describe("spec", function() {
+      it("throws on non-boolean value", function() {
+        expect(function() {
           es2015(null, { spec: 1 });
         }).to.throw(/must be a boolean/);
       });
     });
 
-    describe("modules", function () {
-      it("doesn't throw when passing one false", function () {
-        expect(function () {
+    describe("modules", function() {
+      it("doesn't throw when passing one false", function() {
+        expect(function() {
           es2015(null, { modules: false });
         }).not.to.throw();
       });
 
-      it("doesn't throw when passing one of: 'commonjs', 'amd', 'umd', 'systemjs", function () {
-        expect(function () {
+      it("doesn't throw when passing one of: 'commonjs', 'amd', 'umd', 'systemjs", function() {
+        expect(function() {
           es2015(null, { modules: "commonjs" });
         }).not.to.throw();
 
-        expect(function () {
+        expect(function() {
           es2015(null, { modules: "amd" });
         }).not.to.throw();
 
-        expect(function () {
+        expect(function() {
           es2015(null, { modules: "umd" });
         }).not.to.throw();
 
-        expect(function () {
+        expect(function() {
           es2015(null, { modules: "systemjs" });
         }).not.to.throw();
       });
 
-      it("throws when passing neither false nor one of: 'commonjs', 'amd', 'umd', 'systemjs'", function () {
-        expect(function () {
+      it("throws when passing neither false nor one of: 'commonjs', 'amd', 'umd', 'systemjs'", function() {
+        expect(function() {
           es2015(null, { modules: 1 });
         }).to.throw();
       });
diff --git a/packages/babel-preset-es2015/test/traceur.js b/packages/babel-preset-es2015/test/traceur.js
index ce7577a5e5..98525618fe 100644
--- a/packages/babel-preset-es2015/test/traceur.js
+++ b/packages/babel-preset-es2015/test/traceur.js
@@ -1,88 +1,92 @@
 import includes from "lodash/includes";
 import runner from "babel-helper-transform-fixture-test-runner";
 
-runner(`${__dirname}/fixtures/traceur`, "traceur", {
-  ignoreSuites: [
-    // weird environmental issue make these hard to test
-    "Modules",
+runner(
+  `${__dirname}/fixtures/traceur`,
+  "traceur",
+  {
+    ignoreSuites: [
+      // weird environmental issue make these hard to test
+      "Modules",
 
-    // uses the old async generator proposal
-    "AsyncGenerators",
-  ],
+      // uses the old async generator proposal
+      "AsyncGenerators",
+    ],
 
-  ignoreTasks: [
-    // Node 0.10 doesn't like these due to either V8 bugs or lack of core-js functionality
-    "Symbol/Object",
-    "Symbol/ObjectModel",
-    "Symbol/GetOwnPropertySymbols",
+    ignoreTasks: [
+      // Node 0.10 doesn't like these due to either V8 bugs or lack of core-js functionality
+      "Symbol/Object",
+      "Symbol/ObjectModel",
+      "Symbol/GetOwnPropertySymbols",
 
-    // TODO
-    "Yield/GeneratorSend",
-    "Yield/BreakForOf",
-    "Yield/GeneratorThrow",
-    "Yield/ObjectModel",
-    "Yield/ReturnGenerator",
+      // TODO
+      "Yield/GeneratorSend",
+      "Yield/BreakForOf",
+      "Yield/GeneratorThrow",
+      "Yield/ObjectModel",
+      "Yield/ReturnGenerator",
 
-    // yield as an identifier
-    "Yield/YieldIdentifier",
-    "Syntax/StrictKeywords",
-    "Syntax/IsValidSimpleAssignmentTarget",
+      // yield as an identifier
+      "Yield/YieldIdentifier",
+      "Syntax/StrictKeywords",
+      "Syntax/IsValidSimpleAssignmentTarget",
 
-    // TODO: core-js fails these
-    "Collections/Map",
-    "Collections/Set",
-    "ArrayExtras/From",
-    "ArrayExtras/FindIndex",
-    "ArrayExtras/Find",
-    "StringExtras/Includes",
-    "StringExtras/EndsWith",
+      // TODO: core-js fails these
+      "Collections/Map",
+      "Collections/Set",
+      "ArrayExtras/From",
+      "ArrayExtras/FindIndex",
+      "ArrayExtras/Find",
+      "StringExtras/Includes",
+      "StringExtras/EndsWith",
 
-    // this tests pollutes Object.prototype which messes things up
-    "StringExtras/StartsWith",
+      // this tests pollutes Object.prototype which messes things up
+      "StringExtras/StartsWith",
 
-    // babel has no way to check these :( TODO: add to caveats
-    "TemplateLiterals/TemplateObjectCaching.module",
+      // babel has no way to check these :( TODO: add to caveats
+      "TemplateLiterals/TemplateObjectCaching.module",
 
-    // babel does function/class name inference which these tests don't take into consideration
-    "Classes/ClassNameBinding",
-    "PropertyMethodAssignment/PropertyMethodAssignment",
+      // babel does function/class name inference which these tests don't take into consideration
+      "Classes/ClassNameBinding",
+      "PropertyMethodAssignment/PropertyMethodAssignment",
 
-    // TODO: investigate
-    "Classes/ExtendStrange",
-    "Math/fround.module",
+      // TODO: investigate
+      "Classes/ExtendStrange",
+      "Math/fround.module",
 
-    // these are the responsibility of core-js
-    "Spread/Type",
-    "Spread/NoIterator",
-    "Destructuring/Rest",
-    "Destructuring/Empty",
+      // these are the responsibility of core-js
+      "Spread/Type",
+      "Spread/NoIterator",
+      "Destructuring/Rest",
+      "Destructuring/Empty",
 
-    // babel doesn't like non-closing comments :)
-    "Syntax/NoNewLineHereEndOfFile",
+      // babel doesn't like non-closing comments :)
+      "Syntax/NoNewLineHereEndOfFile",
 
-    // TODO
-    "Classes/PrototypeDescriptor",
+      // TODO
+      "Classes/PrototypeDescriptor",
 
-    // Babel assumes that all code transformed is a module so this isn't necessary
-    "Strict",
-    "Syntax/UseStrictEscapeSequence",
-    "Syntax/UseStrictLineContinuation",
-    "ObjectInitializerShorthand/StrictKeyword",
+      // Babel assumes that all code transformed is a module so this isn't necessary
+      "Strict",
+      "Syntax/UseStrictEscapeSequence",
+      "Syntax/UseStrictLineContinuation",
+      "ObjectInitializerShorthand/StrictKeyword",
 
-    // experimental es7 - the spec hasn't been finalized yet
-    // these both fail because of filters between blocks
-    "ArrayComprehension/Simple",
-    "GeneratorComprehension/Simple",
+      // experimental es7 - the spec hasn't been finalized yet
+      // these both fail because of filters between blocks
+      "ArrayComprehension/Simple",
+      "GeneratorComprehension/Simple",
 
-    // TODO
-    "Syntax/StrictKeywordsInPattern",
-  ],
-}, {
-
-}, function (opts, task) {
-  if (includes(task.exec.loc, "module.js")) {
-    opts.plugins.push("transform-es2015-modules-commonjs");
-  } else {
-    opts.sourceType = "script";
-  }
-});
+      // TODO
+      "Syntax/StrictKeywordsInPattern",
+    ],
+  },
+  {},
+  function(opts, task) {
+    if (includes(task.exec.loc, "module.js")) {
+      opts.plugins.push("transform-es2015-modules-commonjs");
+    } else {
+      opts.sourceType = "script";
+    }
+  },
+);
diff --git a/packages/babel-preset-es2016/src/index.js b/packages/babel-preset-es2016/src/index.js
index ae2a519918..a9fdd007da 100644
--- a/packages/babel-preset-es2016/src/index.js
+++ b/packages/babel-preset-es2016/src/index.js
@@ -1,9 +1,7 @@
 import transformExponentiationOperator from "babel-plugin-transform-exponentiation-operator";
 
-export default function () {
+export default function() {
   return {
-    plugins: [
-      transformExponentiationOperator,
-    ],
+    plugins: [transformExponentiationOperator],
   };
 }
diff --git a/packages/babel-preset-es2017/src/index.js b/packages/babel-preset-es2017/src/index.js
index 735e5aaf57..84503ce7e3 100644
--- a/packages/babel-preset-es2017/src/index.js
+++ b/packages/babel-preset-es2017/src/index.js
@@ -1,11 +1,8 @@
 import syntaxTrailingFunctionCommas from "babel-plugin-syntax-trailing-function-commas";
 import transformAsyncToGenerator from "babel-plugin-transform-async-to-generator";
 
-export default function () {
+export default function() {
   return {
-    plugins: [
-      syntaxTrailingFunctionCommas,
-      transformAsyncToGenerator,
-    ],
+    plugins: [syntaxTrailingFunctionCommas, transformAsyncToGenerator],
   };
 }
diff --git a/packages/babel-preset-flow/src/index.js b/packages/babel-preset-flow/src/index.js
index 84a144a560..f4829387e0 100644
--- a/packages/babel-preset-flow/src/index.js
+++ b/packages/babel-preset-flow/src/index.js
@@ -1,9 +1,7 @@
 import transformFlowStripTypes from "babel-plugin-transform-flow-strip-types";
 
-export default function () {
+export default function() {
   return {
-    plugins: [
-      transformFlowStripTypes,
-    ],
+    plugins: [transformFlowStripTypes],
   };
 }
diff --git a/packages/babel-preset-react/src/index.js b/packages/babel-preset-react/src/index.js
index 99bc2eac3b..f1d1c1cc6a 100644
--- a/packages/babel-preset-react/src/index.js
+++ b/packages/babel-preset-react/src/index.js
@@ -3,15 +3,9 @@ import transformReactJSX from "babel-plugin-transform-react-jsx";
 import transformSyntaxJSX from "babel-plugin-syntax-jsx";
 import transformReactDisplayName from "babel-plugin-transform-react-display-name";
 
-export default function () {
+export default function() {
   return {
-    presets: [
-      presetFlow,
-    ],
-    plugins: [
-      transformReactJSX,
-      transformSyntaxJSX,
-      transformReactDisplayName,
-    ],
+    presets: [presetFlow],
+    plugins: [transformReactJSX, transformSyntaxJSX, transformReactDisplayName],
   };
 }
diff --git a/packages/babel-preset-stage-0/src/index.js b/packages/babel-preset-stage-0/src/index.js
index 7ac934304b..52b941f87c 100644
--- a/packages/babel-preset-stage-0/src/index.js
+++ b/packages/babel-preset-stage-0/src/index.js
@@ -3,14 +3,9 @@ import presetStage1 from "babel-preset-stage-1";
 import transformDoExpressions from "babel-plugin-transform-do-expressions";
 import transformFunctionBind from "babel-plugin-transform-function-bind";
 
-export default function () {
+export default function() {
   return {
-    presets: [
-      presetStage1,
-    ],
-    plugins: [
-      transformDoExpressions,
-      transformFunctionBind,
-    ],
+    presets: [presetStage1],
+    plugins: [transformDoExpressions, transformFunctionBind],
   };
 }
diff --git a/packages/babel-preset-stage-1/src/index.js b/packages/babel-preset-stage-1/src/index.js
index 5a6e69a320..07ddbaaeda 100644
--- a/packages/babel-preset-stage-1/src/index.js
+++ b/packages/babel-preset-stage-1/src/index.js
@@ -5,11 +5,9 @@ import transformExportExtensions from "babel-plugin-transform-export-extensions"
 import transformNumericSeparator from "babel-plugin-transform-numeric-separator";
 import transformOptionalChaining from "babel-plugin-transform-optional-chaining";
 
-export default function () {
+export default function() {
   return {
-    presets: [
-      presetStage2,
-    ],
+    presets: [presetStage2],
     plugins: [
       transformDecorators,
       transformExportExtensions,
diff --git a/packages/babel-preset-stage-2/src/index.js b/packages/babel-preset-stage-2/src/index.js
index 13499d3d3e..26e0db391c 100644
--- a/packages/babel-preset-stage-2/src/index.js
+++ b/packages/babel-preset-stage-2/src/index.js
@@ -2,13 +2,9 @@ import presetStage3 from "babel-preset-stage-3";
 
 import transformClassProperties from "babel-plugin-transform-class-properties";
 
-export default function () {
+export default function() {
   return {
-    presets: [
-      presetStage3,
-    ],
-    plugins: [
-      transformClassProperties,
-    ],
+    presets: [presetStage3],
+    plugins: [transformClassProperties],
   };
 }
diff --git a/packages/babel-preset-stage-3/src/index.js b/packages/babel-preset-stage-3/src/index.js
index 5a2c05c887..c23a4c9e0f 100644
--- a/packages/babel-preset-stage-3/src/index.js
+++ b/packages/babel-preset-stage-3/src/index.js
@@ -3,7 +3,7 @@ import transformAsyncGeneratorFunctions from "babel-plugin-transform-async-gener
 import transformObjectRestSpread from "babel-plugin-transform-object-rest-spread";
 import transformUnicodePropertyRegex from "babel-plugin-transform-unicode-property-regex";
 
-export default function () {
+export default function() {
   return {
     plugins: [
       syntaxDynamicImport,
diff --git a/packages/babel-register/src/browser.js b/packages/babel-register/src/browser.js
index cd9e975861..43394cd539 100644
--- a/packages/babel-register/src/browser.js
+++ b/packages/babel-register/src/browser.js
@@ -1,3 +1,3 @@
 // required to safely use babel/register within a browserify codebase
 
-export default function () {}
+export default function() {}
diff --git a/packages/babel-register/src/cache.js b/packages/babel-register/src/cache.js
index 35639bcf0d..56575820c6 100644
--- a/packages/babel-register/src/cache.js
+++ b/packages/babel-register/src/cache.js
@@ -6,7 +6,10 @@ import * as babel from "babel-core";
 import findCacheDir from "find-cache-dir";
 
 const DEFAULT_CACHE_DIR = findCacheDir({ name: "babel-register" }) || homeOrTmp;
-const DEFAULT_FILENAME = path.join(DEFAULT_CACHE_DIR, `.babel.${babel.version}.${babel.getEnv()}.json`);
+const DEFAULT_FILENAME = path.join(
+  DEFAULT_CACHE_DIR,
+  `.babel.${babel.version}.${babel.getEnv()}.json`,
+);
 const FILENAME: string = process.env.BABEL_CACHE_PATH || DEFAULT_FILENAME;
 let data: Object = {};
 
@@ -20,7 +23,6 @@ export function save() {
   try {
     serialised = JSON.stringify(data, null, "  ");
   } catch (err) {
-
     if (err.message === "Invalid string length") {
       err.message = "Cache too large so it's been cleared.";
       console.error(err.stack);
diff --git a/packages/babel-register/src/node.js b/packages/babel-register/src/node.js
index 6f9254b362..5513a87386 100644
--- a/packages/babel-register/src/node.js
+++ b/packages/babel-register/src/node.js
@@ -37,11 +37,13 @@ function mtime(filename) {
 
 function compile(code, filename) {
   // merge in base options and resolve all the plugins and presets relative to this file
-  const opts = new OptionManager().init(Object.assign(
-    { sourceRoot: path.dirname(filename) }, // sourceRoot can be overwritten
-    deepClone(transformOpts),
-    { filename }
-  ));
+  const opts = new OptionManager().init(
+    Object.assign(
+      { sourceRoot: path.dirname(filename) }, // sourceRoot can be overwritten
+      deepClone(transformOpts),
+      { filename },
+    ),
+  );
 
   // Bail out ASAP if the file has been ignored.
   if (opts === null) return code;
@@ -59,13 +61,16 @@ function compile(code, filename) {
     }
   }
 
-  const result = babel.transform(code, Object.assign(opts, {
-    // Do not process config files since has already been done with the OptionManager
-    // calls above and would introduce duplicates.
-    babelrc: false,
-    sourceMaps: "both",
-    ast: false,
-  }));
+  const result = babel.transform(
+    code,
+    Object.assign(opts, {
+      // Do not process config files since has already been done with the OptionManager
+      // calls above and would introduce duplicates.
+      babelrc: false,
+      sourceMaps: "both",
+      ast: false,
+    }),
+  );
 
   if (cache) {
     cache[cacheKey] = result;
@@ -105,17 +110,23 @@ export default function register(opts?: Object = {}) {
     transformOpts.ignore = [
       // Ignore any node_modules content outside the current working directory.
       new RegExp(
-        "^(?!" + escapeRegExp(process.cwd()) + ").*" +
-        escapeRegExp(path.sep + "node_modules" + path.sep)
-      , "i"),
+        "^(?!" +
+          escapeRegExp(process.cwd()) +
+          ").*" +
+          escapeRegExp(path.sep + "node_modules" + path.sep),
+        "i",
+      ),
 
       // Ignore any node_modules inside the current working directory.
       new RegExp(
         "^" +
-        escapeRegExp(process.cwd()) +
-        "(?:" + path.sep + ".*)?" +
-        escapeRegExp(path.sep + "node_modules" + path.sep)
-      , "i"),
+          escapeRegExp(process.cwd()) +
+          "(?:" +
+          path.sep +
+          ".*)?" +
+          escapeRegExp(path.sep + "node_modules" + path.sep),
+        "i",
+      ),
     ];
   }
 }
diff --git a/packages/babel-register/test/__data__/es2015.js b/packages/babel-register/test/__data__/es2015.js
index 4305d43375..fdc8c1bed4 100644
--- a/packages/babel-register/test/__data__/es2015.js
+++ b/packages/babel-register/test/__data__/es2015.js
@@ -1,3 +1,6 @@
 import a from "assert";
 
-export default () => { a.foo(); return "b"; };
+export default () => {
+  a.foo();
+  return "b";
+};
diff --git a/packages/babel-register/test/cache.js b/packages/babel-register/test/cache.js
index e736f3e484..55cc8e7a40 100644
--- a/packages/babel-register/test/cache.js
+++ b/packages/babel-register/test/cache.js
@@ -18,7 +18,6 @@ function writeCache(data) {
 }
 
 function cleanCache() {
-
   try {
     fs.unlinkSync(testCacheFilename);
   } catch (e) {
@@ -32,7 +31,6 @@ function resetCache() {
 }
 
 describe("babel register", () => {
-
   describe("cache", () => {
     let load, get, save;
 
diff --git a/packages/babel-register/test/index.js b/packages/babel-register/test/index.js
index 262b129a1e..876b46dc46 100644
--- a/packages/babel-register/test/index.js
+++ b/packages/babel-register/test/index.js
@@ -4,16 +4,21 @@ import decache from "decache";
 
 const DATA_ES2015 = require.resolve("./__data__/es2015");
 
-describe("babel-register", function () {
+describe("babel-register", function() {
   let babelRegister;
   let oldCompiler;
 
   function setupRegister(config = {}) {
     babelRegister = require("../lib/node");
-    babelRegister.default(Object.assign({
-      presets: [path.join(__dirname, "../../babel-preset-es2015")],
-      babelrc: false,
-    }, config));
+    babelRegister.default(
+      Object.assign(
+        {
+          presets: [path.join(__dirname, "../../babel-preset-es2015")],
+          babelrc: false,
+        },
+        config,
+      ),
+    );
   }
 
   function revertRegister() {
@@ -52,6 +57,10 @@ describe("babel-register", function () {
 
     revertRegister();
 
-    chai.expect(() => { require(DATA_ES2015); }).to.throw(SyntaxError);
+    chai
+      .expect(() => {
+        require(DATA_ES2015);
+      })
+      .to.throw(SyntaxError);
   });
 });
diff --git a/packages/babel-template/src/index.js b/packages/babel-template/src/index.js
index 3b33f1247a..183e391fda 100644
--- a/packages/babel-template/src/index.js
+++ b/packages/babel-template/src/index.js
@@ -7,7 +7,7 @@ import * as t from "babel-types";
 const FROM_TEMPLATE = "_fromTemplate"; //Symbol(); // todo: probably wont get copied over
 const TEMPLATE_SKIP = Symbol();
 
-export default function (code: string, opts?: Object): Function {
+export default function(code: string, opts?: Object): Function {
   // since we lazy parse the template, we get the current stack so we have the
   // original stack to append if it errors when parsing
   let stack;
@@ -22,21 +22,26 @@ export default function (code: string, opts?: Object): Function {
     }
   }
 
-  opts = Object.assign({
-    allowReturnOutsideFunction: true,
-    allowSuperOutsideMethod: true,
-    preserveComments: false,
-  }, opts);
+  opts = Object.assign(
+    {
+      allowReturnOutsideFunction: true,
+      allowSuperOutsideMethod: true,
+      preserveComments: false,
+    },
+    opts,
+  );
 
-  let getAst = function () {
+  let getAst = function() {
     let ast;
 
     try {
       ast = babylon.parse(code, opts);
 
-      ast = traverse.removeProperties(ast, { preserveComments: opts.preserveComments });
+      ast = traverse.removeProperties(ast, {
+        preserveComments: opts.preserveComments,
+      });
 
-      traverse.cheap(ast, function (node) {
+      traverse.cheap(ast, function(node) {
         node[FROM_TEMPLATE] = true;
       });
     } catch (err) {
@@ -44,14 +49,14 @@ export default function (code: string, opts?: Object): Function {
       throw err;
     }
 
-    getAst = function () {
+    getAst = function() {
       return ast;
     };
 
     return ast;
   };
 
-  return function (...args) {
+  return function(...args) {
     return useTemplate(getAst(), args);
   };
 }
@@ -105,7 +110,8 @@ const templateVisitor = {
   },
 
   exit({ node }) {
-    if (!node.loc)
-      {traverse.clearNode(node);}
+    if (!node.loc) {
+      traverse.clearNode(node);
+    }
   },
 };
diff --git a/packages/babel-template/test/index.js b/packages/babel-template/test/index.js
index 216d6a8939..b74b2abf99 100644
--- a/packages/babel-template/test/index.js
+++ b/packages/babel-template/test/index.js
@@ -4,26 +4,30 @@ import chai from "chai";
 
 const comments = "// Sum two numbers\nconst add = (a, b) => a + b;";
 
-describe("templating", function () {
-  it("import statement will cause parser to throw by default", function () {
-    chai.expect(function () {
-      template("import foo from 'foo'")({});
-    }).to.throw();
+describe("templating", function() {
+  it("import statement will cause parser to throw by default", function() {
+    chai
+      .expect(function() {
+        template("import foo from 'foo'")({});
+      })
+      .to.throw();
   });
 
-  it("import statements are allowed with sourceType: module", function () {
-    chai.expect(function () {
-      template("import foo from 'foo'", { sourceType: "module" })({});
-    }).not.to.throw();
+  it("import statements are allowed with sourceType: module", function() {
+    chai
+      .expect(function() {
+        template("import foo from 'foo'", { sourceType: "module" })({});
+      })
+      .not.to.throw();
   });
 
-  it("should strip comments by default", function () {
+  it("should strip comments by default", function() {
     const code = "const add = (a, b) => a + b;";
     const output = template(comments)();
     chai.expect(generator(output).code).to.be.equal(code);
   });
 
-  it("should preserve comments with a flag", function () {
+  it("should preserve comments with a flag", function() {
     const output = template(comments, { preserveComments: true })();
     chai.expect(generator(output).code).to.be.equal(comments);
   });
diff --git a/packages/babel-traverse/src/cache.js b/packages/babel-traverse/src/cache.js
index d1a3c265d4..50a66a5e60 100644
--- a/packages/babel-traverse/src/cache.js
+++ b/packages/babel-traverse/src/cache.js
@@ -7,9 +7,9 @@ export function clear() {
 }
 
 export function clearPath() {
-  path = new WeakMap;
+  path = new WeakMap();
 }
 
 export function clearScope() {
-  scope = new WeakMap;
+  scope = new WeakMap();
 }
diff --git a/packages/babel-traverse/src/context.js b/packages/babel-traverse/src/context.js
index fd676dc1ec..a19df4b0c9 100644
--- a/packages/babel-traverse/src/context.js
+++ b/packages/babel-traverse/src/context.js
@@ -84,9 +84,7 @@ export default class TraversalContext {
 
   visitSingle(node, key): boolean {
     if (this.shouldVisit(node[key])) {
-      return this.visitQueue([
-        this.create(node, node, key),
-      ]);
+      return this.visitQueue([this.create(node, node, key)]);
     } else {
       return false;
     }
@@ -104,7 +102,10 @@ export default class TraversalContext {
     for (const path of queue) {
       path.resync();
 
-      if (path.contexts.length === 0 || path.contexts[path.contexts.length - 1] !== this) {
+      if (
+        path.contexts.length === 0 ||
+        path.contexts[path.contexts.length - 1] !== this
+      ) {
         // The context might already have been pushed when this path was inserted and queued.
         // If we always re-pushed here, we could get duplicates and risk leaving contexts
         // on the stack after the traversal has completed, which could break things.
diff --git a/packages/babel-traverse/src/index.js b/packages/babel-traverse/src/index.js
index a3edbada7e..fa0b913f5f 100644
--- a/packages/babel-traverse/src/index.js
+++ b/packages/babel-traverse/src/index.js
@@ -39,17 +39,17 @@ traverse.NodePath = require("./path");
 traverse.Scope = require("./scope");
 traverse.Hub = require("./hub");
 
-traverse.cheap = function (node, enter) {
+traverse.cheap = function(node, enter) {
   return t.traverseFast(node, enter);
 };
 
-traverse.node = function (
+traverse.node = function(
   node: Object,
   opts: Object,
   scope: Object,
   state: Object,
   parentPath: Object,
-  skipKeys?
+  skipKeys?,
 ) {
   const keys: Array = t.VISITOR_KEYS[node.type];
   if (!keys) return;
@@ -61,13 +61,13 @@ traverse.node = function (
   }
 };
 
-traverse.clearNode = function (node, opts) {
+traverse.clearNode = function(node, opts) {
   t.removeProperties(node, opts);
 
   cache.path.delete(node);
 };
 
-traverse.removeProperties = function (tree, opts) {
+traverse.removeProperties = function(tree, opts) {
   t.traverseFast(tree, traverse.clearNode, opts);
   return tree;
 };
@@ -79,11 +79,11 @@ function hasBlacklistedType(path, state) {
   }
 }
 
-traverse.hasType = function (
+traverse.hasType = function(
   tree: Object,
   scope: Object,
   type: Object,
-  blacklistTypes: Array<string>
+  blacklistTypes: Array<string>,
 ): boolean {
   // the node we're searching in is blacklisted
   if (includes(blacklistTypes, tree.type)) return false;
@@ -96,10 +96,15 @@ traverse.hasType = function (
     type: type,
   };
 
-  traverse(tree, {
-    blacklist: blacklistTypes,
-    enter: hasBlacklistedType,
-  }, scope, state);
+  traverse(
+    tree,
+    {
+      blacklist: blacklistTypes,
+      enter: hasBlacklistedType,
+    },
+    scope,
+    state,
+  );
 
   return state.has;
 };
diff --git a/packages/babel-traverse/src/path/ancestry.js b/packages/babel-traverse/src/path/ancestry.js
index beddb0a3fa..7968fb645b 100644
--- a/packages/babel-traverse/src/path/ancestry.js
+++ b/packages/babel-traverse/src/path/ancestry.js
@@ -8,9 +8,9 @@ import NodePath from "./index";
  * When the `callback` returns a truthy value, we return that node path.
  */
 
-export function findParent(callback) : ?NodePath {
+export function findParent(callback): ?NodePath {
   let path = this;
-  while (path = path.parentPath) {
+  while ((path = path.parentPath)) {
     if (callback(path)) return path;
   }
   return null;
@@ -20,11 +20,11 @@ export function findParent(callback) : ?NodePath {
  * Description
  */
 
-export function find(callback) : ?NodePath {
+export function find(callback): ?NodePath {
   let path = this;
   do {
     if (callback(path)) return path;
-  } while (path = path.parentPath);
+  } while ((path = path.parentPath));
   return null;
 }
 
@@ -32,19 +32,22 @@ export function find(callback) : ?NodePath {
  * Get the parent function of the current path.
  */
 
-export function getFunctionParent() : ?NodePath {
-  return this.findParent((path) => path.isFunction() || path.isProgram());
+export function getFunctionParent(): ?NodePath {
+  return this.findParent(path => path.isFunction() || path.isProgram());
 }
 
 /**
  * Walk up the tree until we hit a parent node path in a list.
  */
 
-export function getStatementParent() : NodePath {
+export function getStatementParent(): NodePath {
   let path = this;
 
   do {
-    if (!path.parentPath || (Array.isArray(path.container) && path.isStatement())) {
+    if (
+      !path.parentPath ||
+      (Array.isArray(path.container) && path.isStatement())
+    ) {
       break;
     } else {
       path = path.parentPath;
@@ -52,7 +55,9 @@ export function getStatementParent() : NodePath {
   } while (path);
 
   if (path && (path.isProgram() || path.isFile())) {
-    throw new Error("File/Program node, we can't possibly find a statement parent to this");
+    throw new Error(
+      "File/Program node, we can't possibly find a statement parent to this",
+    );
   }
 
   return path;
@@ -66,8 +71,14 @@ export function getStatementParent() : NodePath {
  * position and visiting key.
  */
 
-export function getEarliestCommonAncestorFrom(paths: Array<NodePath>): NodePath {
-  return this.getDeepestCommonAncestorFrom(paths, function (deepest, i, ancestries) {
+export function getEarliestCommonAncestorFrom(
+  paths: Array<NodePath>,
+): NodePath {
+  return this.getDeepestCommonAncestorFrom(paths, function(
+    deepest,
+    i,
+    ancestries,
+  ) {
     let earliest;
     const keys = t.VISITOR_KEYS[deepest.type];
 
@@ -108,7 +119,10 @@ export function getEarliestCommonAncestorFrom(paths: Array<NodePath>): NodePath
  * TODO: Possible optimisation target.
  */
 
-export function getDeepestCommonAncestorFrom(paths: Array<NodePath>, filter?: Function): NodePath {
+export function getDeepestCommonAncestorFrom(
+  paths: Array<NodePath>,
+  filter?: Function,
+): NodePath {
   if (!paths.length) {
     return this;
   }
@@ -124,7 +138,7 @@ export function getDeepestCommonAncestorFrom(paths: Array<NodePath>, filter?: Fu
   let lastCommonIndex, lastCommon;
 
   // get the ancestors of the path, breaking when the parent exceeds ourselves
-  const ancestries = paths.map((path) => {
+  const ancestries = paths.map(path => {
     const ancestry = [];
 
     do {
@@ -175,30 +189,30 @@ export function getDeepestCommonAncestorFrom(paths: Array<NodePath>, filter?: Fu
  * NOTE: The current node path is included in this.
  */
 
-export function getAncestry() : Array<NodePath> {
+export function getAncestry(): Array<NodePath> {
   let path = this;
   const paths = [];
   do {
     paths.push(path);
-  } while (path = path.parentPath);
+  } while ((path = path.parentPath));
   return paths;
 }
 
 /**
  * A helper to find if `this` path is an ancestor of @param maybeDescendant
  */
-export function isAncestor(maybeDescendant : NodePath) : boolean {
+export function isAncestor(maybeDescendant: NodePath): boolean {
   return maybeDescendant.isDescendant(this);
 }
 
 /**
  * A helper to find if `this` path is a descendant of @param maybeAncestor
  */
-export function isDescendant(maybeAncestor : NodePath) : boolean {
-  return !!this.findParent((parent) => parent === maybeAncestor);
+export function isDescendant(maybeAncestor: NodePath): boolean {
+  return !!this.findParent(parent => parent === maybeAncestor);
 }
 
-export function inType() : boolean {
+export function inType(): boolean {
   let path = this;
   while (path) {
     for (const type of (arguments: Array)) {
diff --git a/packages/babel-traverse/src/path/comments.js b/packages/babel-traverse/src/path/comments.js
index de78503af6..909ea43015 100644
--- a/packages/babel-traverse/src/path/comments.js
+++ b/packages/babel-traverse/src/path/comments.js
@@ -20,7 +20,6 @@ export function shareCommentsWithSiblings() {
   const hasPrev = Boolean(prev.node);
   const hasNext = Boolean(next.node);
   if (hasPrev && hasNext) {
-
   } else if (hasPrev) {
     prev.addComments("trailing", trailing);
   } else if (hasNext) {
@@ -29,10 +28,12 @@ export function shareCommentsWithSiblings() {
 }
 
 export function addComment(type, content, line?) {
-  this.addComments(type, [{
-    type: line ? "CommentLine" : "CommentBlock",
-    value: content,
-  }]);
+  this.addComments(type, [
+    {
+      type: line ? "CommentLine" : "CommentBlock",
+      value: content,
+    },
+  ]);
 }
 
 /**
diff --git a/packages/babel-traverse/src/path/context.js b/packages/babel-traverse/src/path/context.js
index 3f393b6680..50c5364685 100644
--- a/packages/babel-traverse/src/path/context.js
+++ b/packages/babel-traverse/src/path/context.js
@@ -28,7 +28,9 @@ export function _call(fns?: Array<Function>): boolean {
     if (!node) return true;
 
     const ret = fn.call(this.state, this, this.state);
-    if (ret) throw new Error(`Unexpected return value from visitor method ${fn}`);
+    if (ret) {
+      throw new Error(`Unexpected return value from visitor method ${fn}`);
+    }
 
     // node has been replaced, it will have been requeued
     if (this.node !== node) return true;
@@ -63,7 +65,14 @@ export function visit(): boolean {
   }
 
   this.debug(() => "Recursing into...");
-  traverse.node(this.node, this.opts, this.scope, this.state, this, this.skipKeys);
+  traverse.node(
+    this.node,
+    this.opts,
+    this.scope,
+    this.state,
+    this,
+    this.skipKeys,
+  );
 
   this.call("exit");
 
@@ -177,7 +186,11 @@ export function _resyncList() {
 }
 
 export function _resyncRemoved() {
-  if (this.key == null || !this.container || this.container[this.key] !== this.node) {
+  if (
+    this.key == null ||
+    !this.container ||
+    this.container[this.key] !== this.node
+  ) {
     this._markRemoved();
   }
 }
diff --git a/packages/babel-traverse/src/path/conversion.js b/packages/babel-traverse/src/path/conversion.js
index 87d7e5490e..3ae7de7267 100644
--- a/packages/babel-traverse/src/path/conversion.js
+++ b/packages/babel-traverse/src/path/conversion.js
@@ -42,8 +42,14 @@ export function arrowFunctionToShadowed() {
  * to continue behaving as expected.
  */
 export function unwrapFunctionEnvironment() {
-  if (!this.isArrowFunctionExpression() && !this.isFunctionExpression() && !this.isFunctionDeclaration()) {
-    throw this.buildCodeFrameError("Can only unwrap the environment of a function.");
+  if (
+    !this.isArrowFunctionExpression() &&
+    !this.isFunctionExpression() &&
+    !this.isFunctionDeclaration()
+  ) {
+    throw this.buildCodeFrameError(
+      "Can only unwrap the environment of a function.",
+    );
   }
 
   hoistFunctionEnvironment(this);
@@ -52,35 +58,54 @@ export function unwrapFunctionEnvironment() {
 /**
  * Convert a given arrow function into a normal ES5 function expression.
  */
-export function arrowFunctionToExpression({
-  allowInsertArrow = true,
-  specCompliant = false,
-} = {}) {
+export function arrowFunctionToExpression(
+  { allowInsertArrow = true, specCompliant = false } = {},
+) {
   if (!this.isArrowFunctionExpression()) {
-    throw this.buildCodeFrameError("Cannot convert non-arrow function to a function expression.");
+    throw this.buildCodeFrameError(
+      "Cannot convert non-arrow function to a function expression.",
+    );
   }
 
-  const thisBinding = hoistFunctionEnvironment(this, specCompliant, allowInsertArrow);
+  const thisBinding = hoistFunctionEnvironment(
+    this,
+    specCompliant,
+    allowInsertArrow,
+  );
 
   this.ensureBlock();
   this.node.type = "FunctionExpression";
   if (specCompliant) {
-    const checkBinding = thisBinding ? null : this.parentPath.scope.generateUidIdentifier("arrowCheckId");
-    if (checkBinding) this.parentPath.scope.push({ id: checkBinding, init: t.objectExpression([]) });
+    const checkBinding = thisBinding
+      ? null
+      : this.parentPath.scope.generateUidIdentifier("arrowCheckId");
+    if (checkBinding) {
+      this.parentPath.scope.push({
+        id: checkBinding,
+        init: t.objectExpression([]),
+      });
+    }
 
     this.get("body").unshiftContainer(
       "body",
-      t.expressionStatement(t.callExpression(this.hub.file.addHelper("newArrowCheck"), [
-        t.thisExpression(),
-        checkBinding ? t.identifier(checkBinding.name) : t.identifier(thisBinding),
-      ]))
+      t.expressionStatement(
+        t.callExpression(this.hub.file.addHelper("newArrowCheck"), [
+          t.thisExpression(),
+          checkBinding
+            ? t.identifier(checkBinding.name)
+            : t.identifier(thisBinding),
+        ]),
+      ),
     );
 
     this.replaceWith(
       t.callExpression(
-        t.memberExpression(nameFunction(this) || this.node, t.identifier("bind")),
-        [checkBinding ? t.identifier(checkBinding.name) : t.thisExpression()]
-      )
+        t.memberExpression(
+          nameFunction(this) || this.node,
+          t.identifier("bind"),
+        ),
+        [checkBinding ? t.identifier(checkBinding.name) : t.thisExpression()],
+      ),
     );
   }
 }
@@ -89,13 +114,23 @@ export function arrowFunctionToExpression({
  * Given a function, traverse its contents, and if there are references to "this", "arguments", "super",
  * or "new.target", ensure that these references reference the parent environment around this function.
  */
-function hoistFunctionEnvironment(fnPath, specCompliant = false, allowInsertArrow = true) {
+function hoistFunctionEnvironment(
+  fnPath,
+  specCompliant = false,
+  allowInsertArrow = true,
+) {
   const thisEnvFn = fnPath.findParent(
-    (p) => (p.isFunction() && !p.isArrowFunctionExpression()) || p.isProgram() || p.isClassProperty());
+    p =>
+      (p.isFunction() && !p.isArrowFunctionExpression()) ||
+      p.isProgram() ||
+      p.isClassProperty(),
+  );
   const inConstructor = thisEnvFn && thisEnvFn.node.kind === "constructor";
 
   if (thisEnvFn.isClassProperty()) {
-    throw fnPath.buildCodeFrameError("Unable to transform arrow inside class property");
+    throw fnPath.buildCodeFrameError(
+      "Unable to transform arrow inside class property",
+    );
   }
 
   const {
@@ -109,13 +144,21 @@ function hoistFunctionEnvironment(fnPath, specCompliant = false, allowInsertArro
   // Convert all super() calls in the constructor, if super is used in an arrow.
   if (inConstructor && superCalls.length > 0) {
     if (!allowInsertArrow) {
-      throw superCalls[0].buildCodeFrameError("Unable to handle nested super() usage in arrow");
+      throw superCalls[0].buildCodeFrameError(
+        "Unable to handle nested super() usage in arrow",
+      );
     }
 
     const allSuperCalls = [];
     thisEnvFn.traverse({
-      Function: (child) => {
-        if (child.isArrowFunctionExpression() || child.isClassProperty() || child === fnPath) return;
+      Function: child => {
+        if (
+          child.isArrowFunctionExpression() ||
+          child.isClassProperty() ||
+          child === fnPath
+        ) {
+          return;
+        }
         child.skip();
       },
       CallExpression(child) {
@@ -127,7 +170,9 @@ function hoistFunctionEnvironment(fnPath, specCompliant = false, allowInsertArro
 
     const superBinding = getSuperBinding(thisEnvFn);
 
-    allSuperCalls.forEach((superCall) => superCall.get("callee").replaceWith(t.identifier(superBinding)));
+    allSuperCalls.forEach(superCall =>
+      superCall.get("callee").replaceWith(t.identifier(superBinding)),
+    );
   }
 
   // Convert all "this" references in the arrow to point at the alias.
@@ -137,13 +182,16 @@ function hoistFunctionEnvironment(fnPath, specCompliant = false, allowInsertArro
 
     if (
       !specCompliant ||
-
       // In subclass constructors, still need to rewrite because "this" can't be bound in spec mode
       // because it might not have been initialized yet.
       (inConstructor && hasSuperClass(thisEnvFn))
     ) {
-      thisPaths.forEach((thisChild) => {
-        thisChild.replaceWith(thisChild.isJSX() ? t.jSXIdentifier(thisBinding) : t.identifier(thisBinding));
+      thisPaths.forEach(thisChild => {
+        thisChild.replaceWith(
+          thisChild.isJSX()
+            ? t.jSXIdentifier(thisBinding)
+            : t.identifier(thisBinding),
+        );
       });
 
       if (specCompliant) thisBinding = null;
@@ -152,20 +200,22 @@ function hoistFunctionEnvironment(fnPath, specCompliant = false, allowInsertArro
 
   // Convert all "arguments" references in the arrow to point at the alias.
   if (argumentsPaths.length > 0) {
-    const argumentsBinding = getBinding(thisEnvFn, "arguments",
-      () => t.identifier("arguments"));
+    const argumentsBinding = getBinding(thisEnvFn, "arguments", () =>
+      t.identifier("arguments"),
+    );
 
-    argumentsPaths.forEach((argumentsChild) => {
+    argumentsPaths.forEach(argumentsChild => {
       argumentsChild.replaceWith(t.identifier(argumentsBinding));
     });
   }
 
   // Convert all "new.target" references in the arrow to point at the alias.
   if (newTargetPaths.length > 0) {
-    const newTargetBinding = getBinding(thisEnvFn, "newtarget",
-      () => t.metaProperty(t.identifier("new"), t.identifier("target")));
+    const newTargetBinding = getBinding(thisEnvFn, "newtarget", () =>
+      t.metaProperty(t.identifier("new"), t.identifier("target")),
+    );
 
-    newTargetPaths.forEach((argumentsChild) => {
+    newTargetPaths.forEach(argumentsChild => {
       argumentsChild.replaceWith(t.identifier(newTargetBinding));
     });
   }
@@ -173,14 +223,20 @@ function hoistFunctionEnvironment(fnPath, specCompliant = false, allowInsertArro
   // Convert all "super.prop" references to point at aliases.
   if (superProps.length > 0) {
     if (!allowInsertArrow) {
-      throw superProps[0].buildCodeFrameError("Unable to handle nested super.prop usage");
+      throw superProps[0].buildCodeFrameError(
+        "Unable to handle nested super.prop usage",
+      );
     }
 
     const flatSuperProps = superProps.reduce(
-      (acc, superProp) => acc.concat(standardizeSuperProperty(superProp)), []);
+      (acc, superProp) => acc.concat(standardizeSuperProperty(superProp)),
+      [],
+    );
 
-    flatSuperProps.forEach((superProp) => {
-      const key = superProp.node.computed ? "" : superProp.get("property").node.name;
+    flatSuperProps.forEach(superProp => {
+      const key = superProp.node.computed
+        ? ""
+        : superProp.get("property").node.name;
 
       if (superProp.parentPath.isCallExpression({ callee: superProp.node })) {
         const superBinding = getSuperPropCallBinding(thisEnvFn, key);
@@ -193,7 +249,9 @@ function hoistFunctionEnvironment(fnPath, specCompliant = false, allowInsertArro
           superProp.replaceWith(t.identifier(superBinding));
         }
       } else {
-        const isAssignment = superProp.parentPath.isAssignmentExpression({ left: superProp.node });
+        const isAssignment = superProp.parentPath.isAssignmentExpression({
+          left: superProp.node,
+        });
         const superBinding = getSuperPropBinding(thisEnvFn, isAssignment, key);
 
         const args = [];
@@ -204,9 +262,13 @@ function hoistFunctionEnvironment(fnPath, specCompliant = false, allowInsertArro
         if (isAssignment) {
           const value = superProp.parentPath.node.right;
           args.push(value);
-          superProp.parentPath.replaceWith(t.callExpression(t.identifier(superBinding), args));
+          superProp.parentPath.replaceWith(
+            t.callExpression(t.identifier(superBinding), args),
+          );
         } else {
-          superProp.replaceWith(t.callExpression(t.identifier(superBinding), args));
+          superProp.replaceWith(
+            t.callExpression(t.identifier(superBinding), args),
+          );
         }
       }
     });
@@ -216,7 +278,10 @@ function hoistFunctionEnvironment(fnPath, specCompliant = false, allowInsertArro
 }
 
 function standardizeSuperProperty(superProp) {
-  if (superProp.parentPath.isAssignmentExpression() && superProp.parentPath.node.operator !== "=") {
+  if (
+    superProp.parentPath.isAssignmentExpression() &&
+    superProp.parentPath.node.operator !== "="
+  ) {
     const assignmentPath = superProp.parentPath;
 
     const op = assignmentPath.node.operator.slice(0, -1);
@@ -226,37 +291,60 @@ function standardizeSuperProperty(superProp) {
     if (superProp.node.computed) {
       const tmp = superProp.scope.generateDeclaredUidIdentifier("tmp");
 
-      assignmentPath.get("left").replaceWith(
-        t.memberExpression(superProp.node.object,
-          t.assignmentExpression("=", tmp, superProp.node.property), true /* computed */)
-      );
+      assignmentPath
+        .get("left")
+        .replaceWith(
+          t.memberExpression(
+            superProp.node.object,
+            t.assignmentExpression("=", tmp, superProp.node.property),
+            true /* computed */,
+          ),
+        );
 
-      assignmentPath.get("right").replaceWith(
-        t.binaryExpression(op,
-          t.memberExpression(superProp.node.object, t.identifier(tmp.name), true /* computed */),
-          value,
-        )
-      );
+      assignmentPath
+        .get("right")
+        .replaceWith(
+          t.binaryExpression(
+            op,
+            t.memberExpression(
+              superProp.node.object,
+              t.identifier(tmp.name),
+              true /* computed */,
+            ),
+            value,
+          ),
+        );
     } else {
-      assignmentPath.get("left").replaceWith(
-        t.memberExpression(superProp.node.object, superProp.node.property),
-      );
+      assignmentPath
+        .get("left")
+        .replaceWith(
+          t.memberExpression(superProp.node.object, superProp.node.property),
+        );
 
-      assignmentPath.get("right").replaceWith(
-        t.binaryExpression(op,
-          t.memberExpression(superProp.node.object, t.identifier(superProp.node.property.name)),
-          value,
-        )
-      );
+      assignmentPath
+        .get("right")
+        .replaceWith(
+          t.binaryExpression(
+            op,
+            t.memberExpression(
+              superProp.node.object,
+              t.identifier(superProp.node.property.name),
+            ),
+            value,
+          ),
+        );
     }
-    return [ assignmentPath.get("left"), assignmentPath.get("right").get("left") ];
-
+    return [
+      assignmentPath.get("left"),
+      assignmentPath.get("right").get("left"),
+    ];
   } else if (superProp.parentPath.isUpdateExpression()) {
     const updateExpr = superProp.parentPath;
 
     const tmp = superProp.scope.generateDeclaredUidIdentifier("tmp");
-    const computedKey = superProp.node.computed ?
-      superProp.scope.generateDeclaredUidIdentifier("prop") : null;
+    const computedKey = superProp.node.computed
+      ? superProp.scope.generateDeclaredUidIdentifier("prop")
+      : null;
 
     const parts = [
       t.assignmentExpression(
@@ -264,9 +352,9 @@ function standardizeSuperProperty(superProp) {
         tmp,
         t.memberExpression(
           superProp.node.object,
-          computedKey ?
-            t.assignmentExpression("=", computedKey, superProp.node.property) :
-            superProp.node.property,
+          computedKey
+            ? t.assignmentExpression("=", computedKey, superProp.node.property)
+            : superProp.node.property,
           superProp.node.computed,
         ),
       ),
@@ -274,7 +362,9 @@ function standardizeSuperProperty(superProp) {
         "=",
         t.memberExpression(
           superProp.node.object,
-          computedKey ? t.identifier(computedKey.name) : superProp.node.property,
+          computedKey
+            ? t.identifier(computedKey.name)
+            : superProp.node.property,
           superProp.node.computed,
         ),
         t.binaryExpression("+", t.identifier(tmp.name), t.numericLiteral(1)),
@@ -289,25 +379,34 @@ function standardizeSuperProperty(superProp) {
 
     const left = updateExpr.get("expressions.0.right");
     const right = updateExpr.get("expressions.1.left");
-    return [ left, right ];
+    return [left, right];
   }
 
-  return [ superProp ];
+  return [superProp];
 }
 
 function hasSuperClass(thisEnvFn) {
-  return thisEnvFn.isClassMethod() && !!thisEnvFn.parentPath.parentPath.node.superClass;
+  return (
+    thisEnvFn.isClassMethod() &&
+    !!thisEnvFn.parentPath.parentPath.node.superClass
+  );
 }
 
 // Create a binding that evaluates to the "this" of the given function.
 function getThisBinding(thisEnvFn, inConstructor) {
-  return getBinding(thisEnvFn, "this", (thisBinding) => {
+  return getBinding(thisEnvFn, "this", thisBinding => {
     if (!inConstructor || !hasSuperClass(thisEnvFn)) return t.thisExpression();
 
     const supers = new WeakSet();
     thisEnvFn.traverse({
-      Function: (child) => {
-        if (child.isArrowFunctionExpression() || child.isClassProperty() || child === this) return;
+      Function: child => {
+        if (
+          child.isArrowFunctionExpression() ||
+          child.isClassProperty() ||
+          child === this
+        ) {
+          return;
+        }
 
         child.skip();
       },
@@ -316,7 +415,9 @@ function getThisBinding(thisEnvFn, inConstructor) {
         if (supers.has(child.node)) return;
         supers.add(child.node);
 
-        child.replaceWith(t.assignmentExpression("=", t.identifier(thisBinding), child.node));
+        child.replaceWith(
+          t.assignmentExpression("=", t.identifier(thisBinding), child.node),
+        );
       },
     });
   });
@@ -326,9 +427,12 @@ function getThisBinding(thisEnvFn, inConstructor) {
 function getSuperBinding(thisEnvFn) {
   return getBinding(thisEnvFn, "supercall", () => {
     const argsBinding = thisEnvFn.scope.generateUidIdentifier("args");
-    return t.arrowFunctionExpression([t.restElement(argsBinding)], t.callExpression(t.super(), [
-      t.spreadElement(t.identifier(argsBinding.name)),
-    ]));
+    return t.arrowFunctionExpression(
+      [t.restElement(argsBinding)],
+      t.callExpression(t.super(), [
+        t.spreadElement(t.identifier(argsBinding.name)),
+      ]),
+    );
   });
 }
 
@@ -336,22 +440,26 @@ function getSuperBinding(thisEnvFn) {
 function getSuperPropCallBinding(thisEnvFn, propName) {
   return getBinding(thisEnvFn, `superprop_call:${propName || ""}`, () => {
     const argsBinding = thisEnvFn.scope.generateUidIdentifier("args");
-    const argsList = [ t.restElement(argsBinding) ];
+    const argsList = [t.restElement(argsBinding)];
 
     let fnBody;
     if (propName) {
       // (...args) => super.foo(...args)
       fnBody = t.callExpression(
         t.memberExpression(t.super(), t.identifier(propName)),
-        [ t.spreadElement(t.identifier(argsBinding.name)) ],
+        [t.spreadElement(t.identifier(argsBinding.name))],
       );
     } else {
       const method = thisEnvFn.scope.generateUidIdentifier("prop");
       // (method, ...args) => super[method](...args)
       argsList.unshift(method);
       fnBody = t.callExpression(
-        t.memberExpression(t.super(), t.identifier(method.name), true /* computed */),
-        [ t.spreadElement(t.identifier(argsBinding.name)) ],
+        t.memberExpression(
+          t.super(),
+          t.identifier(method.name),
+          true /* computed */,
+        ),
+        [t.spreadElement(t.identifier(argsBinding.name))],
       );
     }
 
@@ -374,14 +482,22 @@ function getSuperPropBinding(thisEnvFn, isAssignment, propName) {
       const method = thisEnvFn.scope.generateUidIdentifier("prop");
       // (method) => super[method]
       argsList.unshift(method);
-      fnBody = t.memberExpression(t.super(), t.identifier(method.name), true /* computed */);
+      fnBody = t.memberExpression(
+        t.super(),
+        t.identifier(method.name),
+        true /* computed */,
+      );
     }
 
     if (isAssignment) {
       const valueIdent = thisEnvFn.scope.generateUidIdentifier("value");
       argsList.push(valueIdent);
 
-      fnBody = t.assignmentExpression("=", fnBody, t.identifier(valueIdent.name));
+      fnBody = t.assignmentExpression(
+        "=",
+        fnBody,
+        t.identifier(valueIdent.name),
+      );
     }
 
     return t.arrowFunctionExpression(argsList, fnBody);
@@ -425,7 +541,9 @@ function getScopeInformation(fnPath) {
       if (
         !child.parentPath.isJSXMemberExpression({ object: child.node }) &&
         !child.parentPath.isJSXOpeningElement({ name: child.node })
-      ) return;
+      ) {
+        return;
+      }
 
       thisPaths.push(child);
     },
diff --git a/packages/babel-traverse/src/path/evaluation.js b/packages/babel-traverse/src/path/evaluation.js
index 46945f0083..60de0dcbea 100644
--- a/packages/babel-traverse/src/path/evaluation.js
+++ b/packages/babel-traverse/src/path/evaluation.js
@@ -80,7 +80,11 @@ function _evaluate(path, state) {
     return evaluateCached(exprs[exprs.length - 1], state);
   }
 
-  if (path.isStringLiteral() || path.isNumericLiteral() || path.isBooleanLiteral()) {
+  if (
+    path.isStringLiteral() ||
+    path.isNumericLiteral() ||
+    path.isBooleanLiteral()
+  ) {
     return node.value;
   }
 
@@ -92,14 +96,20 @@ function _evaluate(path, state) {
     return evaluateQuasis(path, node.quasis, state);
   }
 
-  if (path.isTaggedTemplateExpression() && path.get("tag").isMemberExpression()) {
+  if (
+    path.isTaggedTemplateExpression() &&
+    path.get("tag").isMemberExpression()
+  ) {
     const object = path.get("tag.object");
     const { node: { name } } = object;
     const property = path.get("tag.property");
 
     if (
-      object.isIdentifier() && name === "String" && !path.scope.getBinding(name, true) &&
-      property.isIdentifier && property.node.name === "raw"
+      object.isIdentifier() &&
+      name === "String" &&
+      !path.scope.getBinding(name, true) &&
+      property.isIdentifier &&
+      property.node.name === "raw"
     ) {
       return evaluateQuasis(path, node.quasi.quasis, state, true);
     }
@@ -115,12 +125,16 @@ function _evaluate(path, state) {
     }
   }
 
-  if (path.isExpressionWrapper()) { // TypeCastExpression, ExpressionStatement etc
+  if (path.isExpressionWrapper()) {
+    // TypeCastExpression, ExpressionStatement etc
     return evaluateCached(path.get("expression"), state);
   }
 
   // "foo".length
-  if (path.isMemberExpression() && !path.parentPath.isCallExpression({ callee: node })) {
+  if (
+    path.isMemberExpression() &&
+    !path.parentPath.isCallExpression({ callee: node })
+  ) {
     const property = path.get("property");
     const object = path.get("object");
 
@@ -171,18 +185,26 @@ function _evaluate(path, state) {
     }
 
     const argument = path.get("argument");
-    if (node.operator === "typeof" && (argument.isFunction() || argument.isClass())) {
+    if (
+      node.operator === "typeof" &&
+      (argument.isFunction() || argument.isClass())
+    ) {
       return "function";
     }
 
     const arg = evaluateCached(argument, state);
     if (!state.confident) return;
     switch (node.operator) {
-      case "!": return !arg;
-      case "+": return +arg;
-      case "-": return -arg;
-      case "~": return ~arg;
-      case "typeof": return typeof arg;
+      case "!":
+        return !arg;
+      case "+":
+        return +arg;
+      case "-":
+        return -arg;
+      case "~":
+        return ~arg;
+      case "typeof":
+        return typeof arg;
     }
   }
 
@@ -273,26 +295,46 @@ function _evaluate(path, state) {
     if (!state.confident) return;
 
     switch (node.operator) {
-      case "-": return left - right;
-      case "+": return left + right;
-      case "/": return left / right;
-      case "*": return left * right;
-      case "%": return left % right;
-      case "**": return left ** right;
-      case "<": return left < right;
-      case ">": return left > right;
-      case "<=": return left <= right;
-      case ">=": return left >= right;
-      case "==": return left == right; // eslint-disable-line eqeqeq
-      case "!=": return left != right;
-      case "===": return left === right;
-      case "!==": return left !== right;
-      case "|": return left | right;
-      case "&": return left & right;
-      case "^": return left ^ right;
-      case "<<": return left << right;
-      case ">>": return left >> right;
-      case ">>>": return left >>> right;
+      case "-":
+        return left - right;
+      case "+":
+        return left + right;
+      case "/":
+        return left / right;
+      case "*":
+        return left * right;
+      case "%":
+        return left % right;
+      case "**":
+        return left ** right;
+      case "<":
+        return left < right;
+      case ">":
+        return left > right;
+      case "<=":
+        return left <= right;
+      case ">=":
+        return left >= right;
+      case "==":
+        return left == right; // eslint-disable-line eqeqeq
+      case "!=":
+        return left != right;
+      case "===":
+        return left === right;
+      case "!==":
+        return left !== right;
+      case "|":
+        return left | right;
+      case "&":
+        return left & right;
+      case "^":
+        return left ^ right;
+      case "<<":
+        return left << right;
+      case ">>":
+        return left >> right;
+      case ">>>":
+        return left >>> right;
     }
   }
 
@@ -303,7 +345,8 @@ function _evaluate(path, state) {
 
     // Number(1);
     if (
-      callee.isIdentifier() && !path.scope.getBinding(callee.node.name, true) &&
+      callee.isIdentifier() &&
+      !path.scope.getBinding(callee.node.name, true) &&
       VALID_CALLEES.indexOf(callee.node.name) >= 0
     ) {
       func = global[node.callee.name];
@@ -315,7 +358,8 @@ function _evaluate(path, state) {
 
       // Math.min(1, 2)
       if (
-        object.isIdentifier() && property.isIdentifier() &&
+        object.isIdentifier() &&
+        property.isIdentifier() &&
         VALID_CALLEES.indexOf(object.node.name) >= 0 &&
         INVALID_METHODS.indexOf(property.node.name) < 0
       ) {
@@ -334,7 +378,7 @@ function _evaluate(path, state) {
     }
 
     if (func) {
-      const args = path.get("arguments").map((arg) => evaluateCached(arg, state));
+      const args = path.get("arguments").map(arg => evaluateCached(arg, state));
       if (!state.confident) return;
 
       return func.apply(context, args);
@@ -344,7 +388,7 @@ function _evaluate(path, state) {
   deopt(path, state);
 }
 
-function evaluateQuasis (path, quasis: Array<Object>, state, raw = false) {
+function evaluateQuasis(path, quasis: Array<Object>, state, raw = false) {
   let str = "";
 
   let i = 0;
@@ -381,11 +425,11 @@ function evaluateQuasis (path, quasis: Array<Object>, state, raw = false) {
  *
  */
 
-export function evaluate(): { confident: boolean; value: any } {
+export function evaluate(): { confident: boolean, value: any } {
   const state = {
     confident: true,
     deoptPath: null,
-    seen: new Map,
+    seen: new Map(),
   };
   let value = evaluateCached(this, state);
   if (!state.confident) value = undefined;
diff --git a/packages/babel-traverse/src/path/family.js b/packages/babel-traverse/src/path/family.js
index e2ab999829..9fe3ded555 100644
--- a/packages/babel-traverse/src/path/family.js
+++ b/packages/babel-traverse/src/path/family.js
@@ -4,7 +4,7 @@ import type TraversalContext from "../index";
 import NodePath from "./index";
 import * as t from "babel-types";
 
-export function getOpposite() : ?NodePath {
+export function getOpposite(): ?NodePath {
   if (this.key === "left") {
     return this.getSibling("right");
   } else if (this.key === "right") {
@@ -60,8 +60,8 @@ export function getNextSibling(): NodePath {
 
 export function getAllNextSiblings(): Array<NodePath> {
   let _key = this.key;
-  let sibling:NodePath = this.getSibling(++_key);
-  const siblings:Array<NodePath> = [];
+  let sibling: NodePath = this.getSibling(++_key);
+  const siblings: Array<NodePath> = [];
   while (sibling.node) {
     siblings.push(sibling);
     sibling = this.getSibling(++_key);
@@ -71,8 +71,8 @@ export function getAllNextSiblings(): Array<NodePath> {
 
 export function getAllPrevSiblings(): Array<NodePath> {
   let _key = this.key;
-  let sibling:NodePath = this.getSibling(--_key);
-  const siblings:Array<NodePath> = [];
+  let sibling: NodePath = this.getSibling(--_key);
+  const siblings: Array<NodePath> = [];
   while (sibling.node) {
     siblings.push(sibling);
     sibling = this.getSibling(--_key);
@@ -80,12 +80,17 @@ export function getAllPrevSiblings(): Array<NodePath> {
   return siblings;
 }
 
-export function get(key: string, context?: boolean | TraversalContext): NodePath {
+export function get(
+  key: string,
+  context?: boolean | TraversalContext,
+): NodePath {
   if (context === true) context = this.context;
   const parts = key.split(".");
-  if (parts.length === 1) { // "foo"
+  if (parts.length === 1) {
+    // "foo"
     return this._getKey(key, context);
-  } else { // "foo.bar"
+  } else {
+    // "foo.bar"
     return this._getPattern(parts, context);
   }
 }
@@ -142,7 +147,10 @@ export function getOuterBindingIdentifiers(duplicates?): Object {
 // original source - https://github.com/babel/babel/blob/master/packages/babel-types/src/retrievers.js
 // path.getBindingIdentifiers returns nodes where the following re-implementation
 // returns paths
-export function getBindingIdentifierPaths(duplicates = false, outerOnly = false) {
+export function getBindingIdentifierPaths(
+  duplicates = false,
+  outerOnly = false,
+) {
   const path = this;
   let search = [].concat(path);
   const ids = Object.create(null);
@@ -156,7 +164,7 @@ export function getBindingIdentifierPaths(duplicates = false, outerOnly = false)
 
     if (id.isIdentifier()) {
       if (duplicates) {
-        const _ids = ids[id.node.name] = ids[id.node.name] || [];
+        const _ids = (ids[id.node.name] = ids[id.node.name] || []);
         _ids.push(id);
       } else {
         ids[id.node.name] = id;
diff --git a/packages/babel-traverse/src/path/index.js b/packages/babel-traverse/src/path/index.js
index b5bdba44a4..dbbd8e2bab 100644
--- a/packages/babel-traverse/src/path/index.js
+++ b/packages/babel-traverse/src/path/index.js
@@ -116,7 +116,7 @@ export default class NodePath {
   }
 
   setData(key: string, val: any): any {
-    return this.data[key] = val;
+    return (this.data[key] = val);
   }
 
   getData(key: string, def?: any): any {
@@ -153,7 +153,7 @@ export default class NodePath {
       let key = path.key;
       if (path.inList) key = `${path.listKey}[${key}]`;
       parts.unshift(key);
-    } while (path = path.parentPath);
+    } while ((path = path.parentPath));
     return parts.join(".");
   }
 
@@ -163,7 +163,8 @@ export default class NodePath {
   }
 }
 
-Object.assign(NodePath.prototype,
+Object.assign(
+  NodePath.prototype,
   NodePath_ancestry,
   NodePath_inference,
   NodePath_replacement,
@@ -174,15 +175,16 @@ Object.assign(NodePath.prototype,
   NodePath_removal,
   NodePath_modification,
   NodePath_family,
-  NodePath_comments);
+  NodePath_comments,
+);
 
 for (const type of (t.TYPES: Array<string>)) {
   const typeKey = `is${type}`;
-  NodePath.prototype[typeKey] = function (opts) {
+  NodePath.prototype[typeKey] = function(opts) {
     return t[typeKey](this.node, opts);
   };
 
-  NodePath.prototype[`assert${type}`] = function (opts) {
+  NodePath.prototype[`assert${type}`] = function(opts) {
     if (!this[typeKey](opts)) {
       throw new TypeError(`Expected node path of type ${type}`);
     }
@@ -195,7 +197,7 @@ for (const type in virtualTypes) {
 
   const virtualType = virtualTypes[type];
 
-  NodePath.prototype[`is${type}`] = function (opts) {
+  NodePath.prototype[`is${type}`] = function(opts) {
     return virtualType.checkPath(this, opts);
   };
 }
diff --git a/packages/babel-traverse/src/path/inference/index.js b/packages/babel-traverse/src/path/inference/index.js
index c782b2779f..1f515a100c 100644
--- a/packages/babel-traverse/src/path/inference/index.js
+++ b/packages/babel-traverse/src/path/inference/index.js
@@ -11,7 +11,7 @@ export function getTypeAnnotation(): Object {
 
   let type = this._getTypeAnnotation() || t.anyTypeAnnotation();
   if (t.isTypeAnnotation(type)) type = type.typeAnnotation;
-  return this.typeAnnotation = type;
+  return (this.typeAnnotation = type);
 }
 
 /**
@@ -113,5 +113,8 @@ export function baseTypeStrictlyMatches(right: NodePath) {
 
 export function isGenericType(genericName: string): boolean {
   const type = this.getTypeAnnotation();
-  return t.isGenericTypeAnnotation(type) && t.isIdentifier(type.id, { name: genericName });
+  return (
+    t.isGenericTypeAnnotation(type) &&
+    t.isIdentifier(type.id, { name: genericName })
+  );
 }
diff --git a/packages/babel-traverse/src/path/inference/inferer-reference.js b/packages/babel-traverse/src/path/inference/inferer-reference.js
index 9b95794a75..c2774f1480 100644
--- a/packages/babel-traverse/src/path/inference/inferer-reference.js
+++ b/packages/babel-traverse/src/path/inference/inferer-reference.js
@@ -1,7 +1,7 @@
 import type NodePath from "../index";
 import * as t from "babel-types";
 
-export default function (node: Object) {
+export default function(node: Object) {
   if (!this.isReferenced()) return;
 
   // check if a binding exists of this value and if so then return a union type of all
@@ -32,14 +32,23 @@ function getTypeAnnotationBindingConstantViolations(path, name) {
   path.typeAnnotation = t.unionTypeAnnotation(types);
 
   const functionConstantViolations = [];
-  let constantViolations = getConstantViolationsBefore(binding, path, functionConstantViolations);
+  let constantViolations = getConstantViolationsBefore(
+    binding,
+    path,
+    functionConstantViolations,
+  );
 
   const testType = getConditionalAnnotation(path, name);
   if (testType) {
-    const testConstantViolations = getConstantViolationsBefore(binding, testType.ifStatement);
+    const testConstantViolations = getConstantViolationsBefore(
+      binding,
+      testType.ifStatement,
+    );
 
     // remove constant violations observed before the IfStatement
-    constantViolations = constantViolations.filter((path) => testConstantViolations.indexOf(path) < 0);
+    constantViolations = constantViolations.filter(
+      path => testConstantViolations.indexOf(path) < 0,
+    );
 
     // clear current types and add in observed test type
     types.push(testType.typeAnnotation);
@@ -89,7 +98,7 @@ function getTypeAnnotationBindingConstantViolations(path, name) {
 function getConstantViolationsBefore(binding, path, functions) {
   const violations = binding.constantViolations.slice();
   violations.unshift(binding.path);
-  return violations.filter((violation) => {
+  return violations.filter(violation => {
     violation = violation.resolve();
     const status = violation._guessExecutionStatusRelativeTo(path);
     if (functions && status === "function") functions.push(violation);
@@ -150,7 +159,7 @@ function inferAnnotationFromBinaryExpression(name, path) {
 
 function getParentConditionalPath(path) {
   let parentPath;
-  while (parentPath = path.parentPath) {
+  while ((parentPath = path.parentPath)) {
     if (parentPath.isIfStatement() || parentPath.isConditionalExpression()) {
       if (path.key === "test") {
         return;
diff --git a/packages/babel-traverse/src/path/introspection.js b/packages/babel-traverse/src/path/introspection.js
index 342bba3e2f..586d039b8c 100644
--- a/packages/babel-traverse/src/path/introspection.js
+++ b/packages/babel-traverse/src/path/introspection.js
@@ -11,7 +11,10 @@ import * as t from "babel-types";
  * parsed nodes of `React.createClass` and `React["createClass"]`.
  */
 
-export function matchesPattern(pattern: string, allowPartial?: boolean): boolean {
+export function matchesPattern(
+  pattern: string,
+  allowPartial?: boolean,
+): boolean {
   return t.matchesPattern(this.node, pattern, allowPartial);
 }
 
@@ -79,7 +82,9 @@ export function isNodeType(type: string): boolean {
  */
 
 export function canHaveVariableDeclarationOrExpression() {
-  return (this.key === "init" || this.key === "left") && this.parentPath.isFor();
+  return (
+    (this.key === "init" || this.key === "left") && this.parentPath.isFor()
+  );
 }
 
 /**
@@ -138,7 +143,10 @@ export function isCompletionRecord(allowInsideFunction?) {
  */
 
 export function isStatementOrBlock() {
-  if (this.parentPath.isLabeledStatement() || t.isBlockStatement(this.container)) {
+  if (
+    this.parentPath.isLabeledStatement() ||
+    t.isBlockStatement(this.container)
+  ) {
     return false;
   } else {
     return includes(t.STATEMENT_OR_BLOCK_KEYS, this.key);
@@ -213,7 +221,9 @@ export function _guessExecutionStatusRelativeTo(target) {
   // here we check the `node` equality as sometimes we may have different paths for the
   // same node due to path thrashing
   if (targetFuncParent.node !== selfFuncParent.node) {
-    const status = this._guessExecutionStatusRelativeToDifferentFunctions(targetFuncParent);
+    const status = this._guessExecutionStatusRelativeToDifferentFunctions(
+      targetFuncParent,
+    );
     if (status) {
       return status;
     } else {
@@ -250,17 +260,26 @@ export function _guessExecutionStatusRelativeTo(target) {
   }
 
   // container list so let's see which one is after the other
-  if (targetRelationship.listKey && targetRelationship.container === selfRelationship.container) {
+  if (
+    targetRelationship.listKey &&
+    targetRelationship.container === selfRelationship.container
+  ) {
     return targetRelationship.key > selfRelationship.key ? "before" : "after";
   }
 
   // otherwise we're associated by a parent node, check which key comes before the other
-  const targetKeyPosition = t.VISITOR_KEYS[targetRelationship.type].indexOf(targetRelationship.key);
-  const selfKeyPosition = t.VISITOR_KEYS[selfRelationship.type].indexOf(selfRelationship.key);
+  const targetKeyPosition = t.VISITOR_KEYS[targetRelationship.type].indexOf(
+    targetRelationship.key,
+  );
+  const selfKeyPosition = t.VISITOR_KEYS[selfRelationship.type].indexOf(
+    selfRelationship.key,
+  );
   return targetKeyPosition > selfKeyPosition ? "before" : "after";
 }
 
-export function _guessExecutionStatusRelativeToDifferentFunctions(targetFuncParent) {
+export function _guessExecutionStatusRelativeToDifferentFunctions(
+  targetFuncParent,
+) {
   const targetFuncPath = targetFuncParent.path;
   if (!targetFuncPath.isFunctionDeclaration()) return;
 
@@ -288,7 +307,9 @@ export function _guessExecutionStatusRelativeToDifferentFunctions(targetFuncPare
   for (const path of referencePaths) {
     // if a reference is a child of the function we're checking against then we can
     // safelty ignore it
-    const childOfFunction = !!path.find((path) => path.node === targetFuncPath.node);
+    const childOfFunction = !!path.find(
+      path => path.node === targetFuncPath.node,
+    );
     if (childOfFunction) continue;
 
     const status = this._guessExecutionStatusRelativeTo(path);
@@ -339,7 +360,7 @@ export function _resolve(dangerous?, resolved?): ?NodePath {
     if (binding.path !== this) {
       const ret = binding.path.resolve(dangerous, resolved);
       // If the identifier resolves to parent node then we can't really resolve it.
-      if (this.find((parent) => parent.node === ret.node)) return;
+      if (this.find(parent => parent.node === ret.node)) return;
       return ret;
     }
   } else if (this.isTypeCastExpression()) {
@@ -363,7 +384,8 @@ export function _resolve(dangerous?, resolved?): ?NodePath {
         const key = prop.get("key");
 
         // { foo: obj }
-        let match = prop.isnt("computed") && key.isIdentifier({ name: targetName });
+        let match =
+          prop.isnt("computed") && key.isIdentifier({ name: targetName });
 
         // { "foo": "obj" } or { ["foo"]: "obj" }
         match = match || key.isLiteral({ value: targetName });
diff --git a/packages/babel-traverse/src/path/lib/hoister.js b/packages/babel-traverse/src/path/lib/hoister.js
index 3f2bf2840c..afc0c3f238 100644
--- a/packages/babel-traverse/src/path/lib/hoister.js
+++ b/packages/babel-traverse/src/path/lib/hoister.js
@@ -18,8 +18,13 @@ const referenceVisitor = {
     if (path.node.name === "this") {
       let scope = path.scope;
       do {
-        if (scope.path.isFunction() && !scope.path.isArrowFunctionExpression()) break;
-      } while (scope = scope.parent);
+        if (
+          scope.path.isFunction() &&
+          !scope.path.isArrowFunctionExpression()
+        ) {
+          break;
+        }
+      } while ((scope = scope.parent));
       if (scope) state.breakOnScopePaths.push(scope.path);
     }
 
@@ -77,7 +82,7 @@ export default class PathHoister {
       if (this.breakOnScopePaths.indexOf(scope.path) >= 0) {
         break;
       }
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
   }
 
   getAttachmentPath() {
@@ -100,7 +105,9 @@ export default class PathHoister {
         const binding = this.bindings[name];
 
         // allow parameter references and expressions in params (like destructuring rest)
-        if (binding.kind === "param" || binding.path.parentKey === "params") continue;
+        if (binding.kind === "param" || binding.path.parentKey === "params") {
+          continue;
+        }
 
         // For each binding, get its attachment parent. This gives us an idea of where we might
         // introduce conflicts.
@@ -213,7 +220,9 @@ export default class PathHoister {
 
     const insertFn = this.attachAfter ? "insertAfter" : "insertBefore";
     attachTo[insertFn]([
-      attachTo.isVariableDeclarator() ? declarator : t.variableDeclaration("var", [declarator]),
+      attachTo.isVariableDeclarator()
+        ? declarator
+        : t.variableDeclaration("var", [declarator]),
     ]);
 
     const parent = this.path.parentPath;
diff --git a/packages/babel-traverse/src/path/lib/removal-hooks.js b/packages/babel-traverse/src/path/lib/removal-hooks.js
index bd720222dd..c54f1a256b 100644
--- a/packages/babel-traverse/src/path/lib/removal-hooks.js
+++ b/packages/babel-traverse/src/path/lib/removal-hooks.js
@@ -5,27 +5,24 @@
  */
 
 export const hooks = [
-  function (self, parent) {
+  function(self, parent) {
     const removeParent =
       // while (NODE);
       // removing the test of a while/switch, we can either just remove it entirely *or* turn the
       // `test` into `true` unlikely that the latter will ever be what's wanted so we just remove
       // the loop to avoid infinite recursion
       (self.key === "test" && (parent.isWhile() || parent.isSwitchCase())) ||
-
       // export NODE;
       // just remove a declaration for an export as this is no longer valid
       (self.key === "declaration" && parent.isExportDeclaration()) ||
-
       // label: NODE
       // stray labeled statement with no body
       (self.key === "body" && parent.isLabeledStatement()) ||
-
       // let NODE;
       // remove an entire declaration if there are no declarators left
-      (self.listKey === "declarations" && parent.isVariableDeclaration() &&
+      (self.listKey === "declarations" &&
+        parent.isVariableDeclaration() &&
         parent.node.declarations.length === 1) ||
-
       // NODE;
       // remove the entire expression statement if there's no expression
       (self.key === "expression" && parent.isExpressionStatement());
@@ -36,7 +33,7 @@ export const hooks = [
     }
   },
 
-  function (self, parent) {
+  function(self, parent) {
     if (parent.isSequenceExpression() && parent.node.expressions.length === 1) {
       // (node, NODE);
       // we've just removed the second element of a sequence expression so let's turn that sequence
@@ -46,24 +43,27 @@ export const hooks = [
     }
   },
 
-  function (self, parent) {
+  function(self, parent) {
     if (parent.isBinary()) {
       // left + NODE;
       // NODE + right;
       // we're in a binary expression, better remove it and replace it with the last expression
       if (self.key === "left") {
         parent.replaceWith(parent.node.right);
-      } else { // key === "right"
+      } else {
+        // key === "right"
         parent.replaceWith(parent.node.left);
       }
       return true;
     }
   },
 
-  function (self, parent) {
+  function(self, parent) {
     if (
-      (parent.isIfStatement() && (self.key === "consequent" || self.key === "alternate")) ||
-      (self.key === "body" && (parent.isLoop() || parent.isArrowFunctionExpression()))
+      (parent.isIfStatement() &&
+        (self.key === "consequent" || self.key === "alternate")) ||
+      (self.key === "body" &&
+        (parent.isLoop() || parent.isArrowFunctionExpression()))
     ) {
       self.replaceWith({
         type: "BlockStatement",
diff --git a/packages/babel-traverse/src/path/modification.js b/packages/babel-traverse/src/path/modification.js
index 4984d45916..5b7ed5678e 100644
--- a/packages/babel-traverse/src/path/modification.js
+++ b/packages/babel-traverse/src/path/modification.js
@@ -14,7 +14,10 @@ export function insertBefore(nodes) {
 
   nodes = this._verifyNodeList(nodes);
 
-  if (this.parentPath.isExpressionStatement() || this.parentPath.isLabeledStatement()) {
+  if (
+    this.parentPath.isExpressionStatement() ||
+    this.parentPath.isLabeledStatement()
+  ) {
     return this.parentPath.insertBefore(nodes);
   } else if (
     this.isNodeType("Expression") ||
@@ -30,8 +33,10 @@ export function insertBefore(nodes) {
       if (this.node) nodes.push(this.node);
       this._replaceWith(t.blockStatement(nodes));
     } else {
-      throw new Error("We don't know what to do with this node type. " +
-        "We were previously a Statement but we can't fit in here?");
+      throw new Error(
+        "We don't know what to do with this node type. " +
+          "We were previously a Statement but we can't fit in here?",
+      );
     }
   }
 
@@ -49,7 +54,12 @@ export function _containerInsert(from, nodes) {
     this.container.splice(to, 0, node);
 
     if (this.context) {
-      const path = this.context.create(this.parent, this.container, to, this.listKey);
+      const path = this.context.create(
+        this.parent,
+        this.container,
+        to,
+        this.listKey,
+      );
 
       // While this path may have a context, there is currently no guarantee that the context
       // will be the active context, because `popContext` may leave a final context in place.
@@ -57,13 +67,15 @@ export function _containerInsert(from, nodes) {
       if (this.context.queue) path.pushContext(this.context);
       paths.push(path);
     } else {
-      paths.push(NodePath.get({
-        parentPath: this.parentPath,
-        parent: this.parent,
-        container: this.container,
-        listKey: this.listKey,
-        key: to,
-      }));
+      paths.push(
+        NodePath.get({
+          parentPath: this.parentPath,
+          parent: this.parent,
+          container: this.container,
+          listKey: this.listKey,
+          key: to,
+        }),
+      );
     }
   }
 
@@ -91,7 +103,8 @@ export function _containerInsertAfter(nodes) {
 
 export function _maybePopFromStatements(nodes) {
   const last = nodes[nodes.length - 1];
-  const isIdentifier = t.isIdentifier(last) ||
+  const isIdentifier =
+    t.isIdentifier(last) ||
     (t.isExpressionStatement(last) && t.isIdentifier(last.expression));
 
   if (isIdentifier && !this.isCompletionRecord()) {
@@ -109,7 +122,10 @@ export function insertAfter(nodes) {
 
   nodes = this._verifyNodeList(nodes);
 
-  if (this.parentPath.isExpressionStatement() || this.parentPath.isLabeledStatement()) {
+  if (
+    this.parentPath.isExpressionStatement() ||
+    this.parentPath.isLabeledStatement()
+  ) {
     return this.parentPath.insertAfter(nodes);
   } else if (
     this.isNodeType("Expression") ||
@@ -117,7 +133,9 @@ export function insertAfter(nodes) {
   ) {
     if (this.node) {
       const temp = this.scope.generateDeclaredUidIdentifier();
-      nodes.unshift(t.expressionStatement(t.assignmentExpression("=", temp, this.node)));
+      nodes.unshift(
+        t.expressionStatement(t.assignmentExpression("=", temp, this.node)),
+      );
       nodes.push(t.expressionStatement(temp));
     }
     this.replaceExpressionWithStatements(nodes);
@@ -127,13 +145,18 @@ export function insertAfter(nodes) {
       return this._containerInsertAfter(nodes);
     } else if (this.isStatementOrBlock()) {
       // Unshift current node if it's not an empty expression
-      if (this.node && (!this.isExpressionStatement() || this.node.expression != null)) {
+      if (
+        this.node &&
+        (!this.isExpressionStatement() || this.node.expression != null)
+      ) {
         nodes.unshift(this.node);
       }
       this._replaceWith(t.blockStatement(nodes));
     } else {
-      throw new Error("We don't know what to do with this node type. " +
-        "We were previously a Statement but we can't fit in here?");
+      throw new Error(
+        "We don't know what to do with this node type. " +
+          "We were previously a Statement but we can't fit in here?",
+      );
     }
   }
 
@@ -181,7 +204,9 @@ export function _verifyNodeList(nodes) {
 
     if (msg) {
       const type = Array.isArray(node) ? "array" : typeof node;
-      throw new Error(`Node list ${msg} with the index of ${i} and type of ${type}`);
+      throw new Error(
+        `Node list ${msg} with the index of ${i} and type of ${type}`,
+      );
     }
   }
 
diff --git a/packages/babel-traverse/src/path/removal.js b/packages/babel-traverse/src/path/removal.js
index 6f6701ceee..5b9352fa46 100644
--- a/packages/babel-traverse/src/path/removal.js
+++ b/packages/babel-traverse/src/path/removal.js
@@ -40,6 +40,8 @@ export function _markRemoved() {
 
 export function _assertUnremoved() {
   if (this.removed) {
-    throw this.buildCodeFrameError("NodePath has been removed so is read-only.");
+    throw this.buildCodeFrameError(
+      "NodePath has been removed so is read-only.",
+    );
   }
 }
diff --git a/packages/babel-traverse/src/path/replacement.js b/packages/babel-traverse/src/path/replacement.js
index df257ec329..1f80d960e4 100644
--- a/packages/babel-traverse/src/path/replacement.js
+++ b/packages/babel-traverse/src/path/replacement.js
@@ -23,9 +23,11 @@ const hoistVariablesVisitor = {
 
     for (const declar of (path.node.declarations: Array<Object>)) {
       if (declar.init) {
-        exprs.push(t.expressionStatement(
-          t.assignmentExpression("=", declar.id, declar.init)
-        ));
+        exprs.push(
+          t.expressionStatement(
+            t.assignmentExpression("=", declar.id, declar.init),
+          ),
+        );
       }
     }
 
@@ -107,7 +109,9 @@ export function replaceWith(replacement) {
   }
 
   if (!replacement) {
-    throw new Error("You passed `path.replaceWith()` a falsy node, use `path.remove()` instead");
+    throw new Error(
+      "You passed `path.replaceWith()` a falsy node, use `path.remove()` instead",
+    );
   }
 
   if (this.node === replacement) {
@@ -115,17 +119,21 @@ export function replaceWith(replacement) {
   }
 
   if (this.isProgram() && !t.isProgram(replacement)) {
-    throw new Error("You can only replace a Program root node with another Program node");
+    throw new Error(
+      "You can only replace a Program root node with another Program node",
+    );
   }
 
   if (Array.isArray(replacement)) {
     throw new Error(
-      "Don't use `path.replaceWith()` with an array of nodes, use `path.replaceWithMultiple()`");
+      "Don't use `path.replaceWith()` with an array of nodes, use `path.replaceWithMultiple()`",
+    );
   }
 
   if (typeof replacement === "string") {
     throw new Error(
-      "Don't use `path.replaceWith()` with a source string, use `path.replaceWithSourceString()`");
+      "Don't use `path.replaceWith()` with a source string, use `path.replaceWithSourceString()`",
+    );
   }
 
   if (this.isNodeType("Statement") && t.isExpression(replacement)) {
@@ -219,11 +227,13 @@ export function replaceExpressionWithStatements(nodes: Array<Object>) {
     this.traverse(hoistVariablesVisitor);
 
     // add implicit returns to all ending expression statements
-    const completionRecords: Array<NodePath> = this.get("callee").getCompletionRecords();
+    const completionRecords: Array<NodePath> = this.get(
+      "callee",
+    ).getCompletionRecords();
     for (const path of completionRecords) {
       if (!path.isExpressionStatement()) continue;
 
-      const loop = path.findParent((path) => path.isLoop());
+      const loop = path.findParent(path => path.isLoop());
       if (loop) {
         let uid = loop.getData("expressionReplacementReturnUid");
 
@@ -236,9 +246,9 @@ export function replaceExpressionWithStatements(nodes: Array<Object>) {
           uid = t.identifier(uid.name);
         }
 
-        path.get("expression").replaceWith(
-          t.assignmentExpression("=", uid, path.node.expression)
-        );
+        path
+          .get("expression")
+          .replaceWith(t.assignmentExpression("=", uid, path.node.expression));
       } else {
         path.replaceWith(t.returnStatement(path.node.expression));
       }
diff --git a/packages/babel-traverse/src/scope/binding.js b/packages/babel-traverse/src/scope/binding.js
index 3edd9407d4..694becff86 100644
--- a/packages/babel-traverse/src/scope/binding.js
+++ b/packages/babel-traverse/src/scope/binding.js
@@ -31,12 +31,11 @@ export default class Binding {
       this.constantViolations = [].concat(
         existing.path,
         existing.constantViolations,
-        this.constantViolations
+        this.constantViolations,
       );
     }
   }
 
-
   constantViolations: Array<NodePath>;
   constant: boolean;
 
diff --git a/packages/babel-traverse/src/scope/index.js b/packages/babel-traverse/src/scope/index.js
index 4b03b0b7c5..a3948b709e 100644
--- a/packages/babel-traverse/src/scope/index.js
+++ b/packages/babel-traverse/src/scope/index.js
@@ -71,7 +71,9 @@ const collectorVisitor = {
   For(path) {
     for (const key of (t.FOR_INIT_KEYS: Array)) {
       const declar = path.get(key);
-      if (declar.isVar()) path.scope.getFunctionParent().registerBinding("var", declar);
+      if (declar.isVar()) {
+        path.scope.getFunctionParent().registerBinding("var", declar);
+      }
     }
   },
 
@@ -80,7 +82,9 @@ const collectorVisitor = {
     if (path.isBlockScoped()) return;
 
     // this will be hit again once we traverse into it after this iteration
-    if (path.isExportDeclaration() && path.get("declaration").isDeclaration()) return;
+    if (path.isExportDeclaration() && path.get("declaration").isDeclaration()) {
+      return;
+    }
 
     // TODO(amasad): remove support for flow as bindings (See warning below).
     //if (path.isFlow()) return;
@@ -168,7 +172,6 @@ const collectorVisitor = {
 let uid = 0;
 
 export default class Scope {
-
   /**
    * This searches the current "scope" and collects all references/bindings
    * within.
@@ -203,12 +206,7 @@ export default class Scope {
    * Variables available in current context.
    */
 
-  static contextVariables = [
-    "arguments",
-    "undefined",
-    "Infinity",
-    "NaN",
-  ];
+  static contextVariables = ["arguments", "undefined", "Infinity", "NaN"];
 
   /**
    * Traverse node with current scope and path.
@@ -248,7 +246,12 @@ export default class Scope {
     do {
       uid = this._generateUid(name, i);
       i++;
-    } while (this.hasLabel(uid) || this.hasBinding(uid) || this.hasGlobal(uid) || this.hasReference(uid));
+    } while (
+      this.hasLabel(uid) ||
+      this.hasBinding(uid) ||
+      this.hasGlobal(uid) ||
+      this.hasReference(uid)
+    );
 
     const program = this.getProgramParent();
     program.references[uid] = true;
@@ -271,7 +274,10 @@ export default class Scope {
    * Generate a unique identifier based on a node.
    */
 
-  generateUidIdentifierBasedOnNode(parent: Object, defaultName?: String): Object {
+  generateUidIdentifierBasedOnNode(
+    parent: Object,
+    defaultName?: String,
+  ): Object {
     let node = parent;
 
     if (t.isAssignmentExpression(parent)) {
@@ -341,12 +347,19 @@ export default class Scope {
 
     const duplicate =
       // don't allow duplicate bindings to exist alongside
-      kind === "let" || local.kind === "let" || local.kind === "const" || local.kind === "module" ||
+      kind === "let" ||
+      local.kind === "let" ||
+      local.kind === "const" ||
+      local.kind === "module" ||
       // don't allow a local of param with a kind of let
-      local.kind === "param" && (kind === "let" || kind === "const");
+      (local.kind === "param" && (kind === "let" || kind === "const"));
 
     if (duplicate) {
-      throw this.hub.file.buildCodeFrameError(id, messages.get("scopeDuplicateDeclaration", name), TypeError);
+      throw this.hub.file.buildCodeFrameError(
+        id,
+        messages.get("scopeDuplicateDeclaration", name),
+        TypeError,
+      );
     }
   }
 
@@ -380,7 +393,7 @@ export default class Scope {
           kind: binding.kind,
         });
       }
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
     console.log(sep);
   }
 
@@ -389,7 +402,9 @@ export default class Scope {
 
     if (t.isIdentifier(node)) {
       const binding = this.getBinding(node.name);
-      if (binding && binding.constant && binding.path.isGenericType("Array")) return node;
+      if (binding && binding.constant && binding.path.isGenericType("Array")) {
+        return node;
+      }
     }
 
     if (t.isArrayExpression(node)) {
@@ -402,13 +417,13 @@ export default class Scope {
           t.memberExpression(
             t.memberExpression(
               t.identifier("Array"),
-              t.identifier("prototype")
+              t.identifier("prototype"),
             ),
-            t.identifier("slice")
+            t.identifier("slice"),
           ),
-          t.identifier("call")
+          t.identifier("call"),
         ),
-        [node]
+        [node],
       );
     }
 
@@ -455,7 +470,11 @@ export default class Scope {
       }
     } else if (path.isExportDeclaration()) {
       const declar = path.get("declaration");
-      if (declar.isClassDeclaration() || declar.isFunctionDeclaration() || declar.isVariableDeclaration()) {
+      if (
+        declar.isClassDeclaration() ||
+        declar.isFunctionDeclaration() ||
+        declar.isVariableDeclaration()
+      ) {
         this.registerDeclaration(declar);
       }
     } else {
@@ -531,7 +550,7 @@ export default class Scope {
 
     do {
       if (scope.uids[name]) return true;
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
 
     return false;
   }
@@ -541,7 +560,7 @@ export default class Scope {
 
     do {
       if (scope.globals[name]) return true;
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
 
     return false;
   }
@@ -551,7 +570,7 @@ export default class Scope {
 
     do {
       if (scope.references[name]) return true;
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
 
     return false;
   }
@@ -563,7 +582,9 @@ export default class Scope {
       if (constantsOnly) return binding.constant;
       return true;
     } else if (t.isClass(node)) {
-      if (node.superClass && !this.isPure(node.superClass, constantsOnly)) return false;
+      if (node.superClass && !this.isPure(node.superClass, constantsOnly)) {
+        return false;
+      }
       return this.isPure(node.body, constantsOnly);
     } else if (t.isClassBody(node)) {
       for (const method of node.body) {
@@ -571,7 +592,10 @@ export default class Scope {
       }
       return true;
     } else if (t.isBinary(node)) {
-      return this.isPure(node.left, constantsOnly) && this.isPure(node.right, constantsOnly);
+      return (
+        this.isPure(node.left, constantsOnly) &&
+        this.isPure(node.right, constantsOnly)
+      );
     } else if (t.isArrayExpression(node)) {
       for (const elem of (node.elements: Array<Object>)) {
         if (!this.isPure(elem, constantsOnly)) return false;
@@ -601,7 +625,7 @@ export default class Scope {
    */
 
   setData(key, val) {
-    return this.data[key] = val;
+    return (this.data[key] = val);
   }
 
   /**
@@ -613,7 +637,7 @@ export default class Scope {
     do {
       const data = scope.data[key];
       if (data != null) return data;
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
   }
 
   /**
@@ -626,7 +650,7 @@ export default class Scope {
     do {
       const data = scope.data[key];
       if (data != null) scope.data[key] = null;
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
   }
 
   init() {
@@ -738,11 +762,11 @@ export default class Scope {
   }
 
   push(opts: {
-    id: Object;
-    init: ?Object;
-    unique: ?boolean;
-    _blockHoist: ?number;
-    kind: "var" | "let";
+    id: Object,
+    init: ?Object,
+    unique: ?boolean,
+    _blockHoist: ?number,
+    kind: "var" | "let",
   }) {
     let path = this.path;
 
@@ -790,7 +814,7 @@ export default class Scope {
       if (scope.path.isProgram()) {
         return scope;
       }
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
     throw new Error("We couldn't find a Function or Program...");
   }
 
@@ -805,7 +829,7 @@ export default class Scope {
       if (scope.path.isFunctionParent()) {
         return scope;
       }
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
     throw new Error("We couldn't find a Function or Program...");
   }
 
@@ -820,8 +844,10 @@ export default class Scope {
       if (scope.path.isBlockParent()) {
         return scope;
       }
-    } while (scope = scope.parent);
-    throw new Error("We couldn't find a BlockStatement, For, Switch, Function, Loop or Program...");
+    } while ((scope = scope.parent));
+    throw new Error(
+      "We couldn't find a BlockStatement, For, Switch, Function, Loop or Program...",
+    );
   }
 
   /**
@@ -882,7 +908,7 @@ export default class Scope {
     do {
       const binding = scope.getOwnBinding(name);
       if (binding) return this.warnOnFlowBinding(binding);
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
   }
 
   getOwnBinding(name: string) {
@@ -947,6 +973,6 @@ export default class Scope {
       if (scope.uids[name]) {
         scope.uids[name] = false;
       }
-    } while (scope = scope.parent);
+    } while ((scope = scope.parent));
   }
 }
diff --git a/packages/babel-traverse/src/scope/lib/renamer.js b/packages/babel-traverse/src/scope/lib/renamer.js
index 2079192e1c..bdb773b9f3 100644
--- a/packages/babel-traverse/src/scope/lib/renamer.js
+++ b/packages/babel-traverse/src/scope/lib/renamer.js
@@ -9,7 +9,12 @@ const renameVisitor = {
   },
 
   Scope(path, state) {
-    if (!path.scope.bindingIdentifierEquals(state.oldName, state.binding.identifier)) {
+    if (
+      !path.scope.bindingIdentifierEquals(
+        state.oldName,
+        state.binding.identifier,
+      )
+    ) {
       path.skip();
     }
   },
@@ -35,17 +40,24 @@ export default class Renamer {
   binding: Binding;
 
   maybeConvertFromExportDeclaration(parentDeclar) {
-    const exportDeclar = parentDeclar.parentPath.isExportDeclaration() && parentDeclar.parentPath;
+    const exportDeclar =
+      parentDeclar.parentPath.isExportDeclaration() && parentDeclar.parentPath;
     if (!exportDeclar) return;
 
     // build specifiers that point back to this export declaration
     const isDefault = exportDeclar.isExportDefaultDeclaration();
 
-    if (isDefault && (parentDeclar.isFunctionDeclaration() ||
-        parentDeclar.isClassDeclaration()) && !parentDeclar.node.id) {
+    if (
+      isDefault &&
+      (parentDeclar.isFunctionDeclaration() ||
+        parentDeclar.isClassDeclaration()) &&
+      !parentDeclar.node.id
+    ) {
       // Ensure that default class and function exports have a name so they have a identifier to
       // reference from the export specifier list.
-      parentDeclar.node.id = parentDeclar.scope.generateUidIdentifier("default");
+      parentDeclar.node.id = parentDeclar.scope.generateUidIdentifier(
+        "default",
+      );
     }
 
     const bindingIdentifiers = parentDeclar.getOuterBindingIdentifiers();
@@ -54,7 +66,9 @@ export default class Renamer {
     for (const name in bindingIdentifiers) {
       const localName = name === this.oldName ? this.newName : name;
       const exportedName = isDefault ? "default" : name;
-      specifiers.push(t.exportSpecifier(t.identifier(localName), t.identifier(exportedName)));
+      specifiers.push(
+        t.exportSpecifier(t.identifier(localName), t.identifier(exportedName)),
+      );
     }
 
     if (specifiers.length) {
@@ -81,9 +95,14 @@ export default class Renamer {
     path.node.id = t.identifier(this.oldName);
     path.node._blockHoist = 3;
 
-    path.replaceWith(t.variableDeclaration("let", [
-      t.variableDeclarator(t.identifier(this.newName), t.toExpression(path.node)),
-    ]));
+    path.replaceWith(
+      t.variableDeclaration("let", [
+        t.variableDeclarator(
+          t.identifier(this.newName),
+          t.toExpression(path.node),
+        ),
+      ]),
+    );
   }
 
   maybeConvertFromClassFunctionExpression(path) {
@@ -100,14 +119,18 @@ export default class Renamer {
       id: t.identifier(this.newName),
     });
 
-    path.replaceWith(t.assignmentExpression("=", t.identifier(this.newName), path.node));
+    path.replaceWith(
+      t.assignmentExpression("=", t.identifier(this.newName), path.node),
+    );
   }
 
   rename(block?) {
     const { binding, oldName, newName } = this;
     const { scope, path } = binding;
 
-    const parentDeclar = path.find((path) => path.isDeclaration() || path.isFunctionExpression());
+    const parentDeclar = path.find(
+      path => path.isDeclaration() || path.isFunctionExpression(),
+    );
     if (parentDeclar) {
       this.maybeConvertFromExportDeclaration(parentDeclar);
     }
diff --git a/packages/babel-traverse/src/visitors.js b/packages/babel-traverse/src/visitors.js
index f8de5b791d..e55662b6c4 100644
--- a/packages/babel-traverse/src/visitors.js
+++ b/packages/babel-traverse/src/visitors.js
@@ -91,7 +91,9 @@ export function explode(visitor) {
 
     const deprecratedKey = t.DEPRECATED_KEYS[nodeType];
     if (deprecratedKey) {
-      console.trace(`Visitor defined for ${nodeType} but it has been renamed to ${deprecratedKey}`);
+      console.trace(
+        `Visitor defined for ${nodeType} but it has been renamed to ${deprecratedKey}`,
+      );
       aliases = [deprecratedKey];
     }
 
@@ -142,9 +144,14 @@ export function verify(visitor) {
       for (const visitorKey in visitors) {
         if (visitorKey === "enter" || visitorKey === "exit") {
           // verify that it just contains functions
-          validateVisitorMethods(`${nodeType}.${visitorKey}`, visitors[visitorKey]);
+          validateVisitorMethods(
+            `${nodeType}.${visitorKey}`,
+            visitors[visitorKey],
+          );
         } else {
-          throw new Error(messages.get("traverseVerifyVisitorProperty", nodeType, visitorKey));
+          throw new Error(
+            messages.get("traverseVerifyVisitorProperty", nodeType, visitorKey),
+          );
         }
       }
     }
@@ -157,12 +164,18 @@ function validateVisitorMethods(path, val) {
   const fns = [].concat(val);
   for (const fn of fns) {
     if (typeof fn !== "function") {
-      throw new TypeError(`Non-function found defined in ${path} with type ${typeof fn}`);
+      throw new TypeError(
+        `Non-function found defined in ${path} with type ${typeof fn}`,
+      );
     }
   }
 }
 
-export function merge(visitors: Array, states: Array = [], wrapper?: ?Function) {
+export function merge(
+  visitors: Array,
+  states: Array = [],
+  wrapper?: ?Function,
+) {
   const rootVisitor = {};
 
   for (let i = 0; i < visitors.length; i++) {
@@ -179,7 +192,7 @@ export function merge(visitors: Array, states: Array = [], wrapper?: ?Function)
         visitorType = wrapWithStateOrWrapper(visitorType, state, wrapper);
       }
 
-      const nodeVisitor = rootVisitor[type] = rootVisitor[type] || {};
+      const nodeVisitor = (rootVisitor[type] = rootVisitor[type] || {});
       mergePair(nodeVisitor, visitorType);
     }
   }
@@ -196,11 +209,11 @@ function wrapWithStateOrWrapper(oldVisitor, state, wrapper: ?Function) {
     // not an enter/exit array of callbacks
     if (!Array.isArray(fns)) continue;
 
-    fns = fns.map(function (fn) {
+    fns = fns.map(function(fn) {
       let newFn = fn;
 
       if (state) {
-        newFn = function (path) {
+        newFn = function(path) {
           return fn.call(state, path, state);
         };
       }
@@ -235,7 +248,7 @@ function ensureCallbackArrays(obj) {
 }
 
 function wrapCheck(wrapper, fn) {
-  const newFn = function (path) {
+  const newFn = function(path) {
     if (wrapper.checkPath(path)) {
       return fn.apply(this, arguments);
     }
@@ -252,7 +265,9 @@ function shouldIgnoreKey(key) {
   if (key === "enter" || key === "exit" || key === "shouldSkip") return true;
 
   // ignore other options
-  if (key === "blacklist" || key === "noScope" || key === "skipKeys") return true;
+  if (key === "blacklist" || key === "noScope" || key === "skipKeys") {
+    return true;
+  }
 
   return false;
 }
diff --git a/packages/babel-traverse/test/ancestry.js b/packages/babel-traverse/test/ancestry.js
index fda574e782..8e7756ae79 100644
--- a/packages/babel-traverse/test/ancestry.js
+++ b/packages/babel-traverse/test/ancestry.js
@@ -3,8 +3,8 @@ import assert from "assert";
 import { parse } from "babylon";
 import { expect } from "chai";
 
-describe("path/ancestry", function () {
-  describe("isAncestor", function () {
+describe("path/ancestry", function() {
+  describe("isAncestor", function() {
     const ast = parse("var a = 1; 'a';");
 
     it("returns true if ancestor", function() {
@@ -15,7 +15,7 @@ describe("path/ancestry", function () {
         },
       });
 
-      const [ programPath, numberPath ] = paths;
+      const [programPath, numberPath] = paths;
 
       assert(programPath.isAncestor(numberPath));
     });
@@ -28,13 +28,13 @@ describe("path/ancestry", function () {
         },
       });
 
-      const [ , numberPath, stringPath ] = paths;
+      const [, numberPath, stringPath] = paths;
 
       assert(!stringPath.isAncestor(numberPath));
     });
   });
 
-  describe("isDescendant", function () {
+  describe("isDescendant", function() {
     const ast = parse("var a = 1; 'a';");
 
     it("returns true if descendant", function() {
@@ -45,7 +45,7 @@ describe("path/ancestry", function () {
         },
       });
 
-      const [ programPath, numberPath ] = paths;
+      const [programPath, numberPath] = paths;
 
       assert(numberPath.isDescendant(programPath));
     });
@@ -58,16 +58,16 @@ describe("path/ancestry", function () {
         },
       });
 
-      const [ , numberPath, stringPath ] = paths;
+      const [, numberPath, stringPath] = paths;
 
       assert(!numberPath.isDescendant(stringPath));
     });
   });
 
-  describe("getStatementParent", function () {
+  describe("getStatementParent", function() {
     const ast = parse("var a = 1;");
-    it("should throw", function () {
-      expect(function () {
+    it("should throw", function() {
+      expect(function() {
         traverse(ast, {
           Program(path) {
             path.getStatementParent();
diff --git a/packages/babel-traverse/test/arrow-transform.js b/packages/babel-traverse/test/arrow-transform.js
index 3d883d5000..597c94f82c 100644
--- a/packages/babel-traverse/test/arrow-transform.js
+++ b/packages/babel-traverse/test/arrow-transform.js
@@ -4,11 +4,11 @@ import { parse } from "babylon";
 import generate from "babel-generator";
 import * as t from "babel-types";
 
-function assertConversion(input, output, {
-  methodName = "method",
-  extend = false,
-  arrowOpts,
-} = {}) {
+function assertConversion(
+  input,
+  output,
+  { methodName = "method", extend = false, arrowOpts } = {},
+) {
   const inputAst = wrapMethod(input, methodName, extend);
   const outputAst = wrapMethod(output, methodName, extend);
 
@@ -16,7 +16,10 @@ function assertConversion(input, output, {
     hub: {
       file: {
         addHelper(helperName) {
-          return t.memberExpression(t.identifier("babelHelpers"), t.identifier(helperName));
+          return t.memberExpression(
+            t.identifier("babelHelpers"),
+            t.identifier(helperName),
+          );
         },
       },
     },
@@ -36,22 +39,27 @@ function assertConversion(input, output, {
 }
 
 function wrapMethod(body, methodName, extend) {
-  return parse(`
-    class Example ${extend ? ("extends class {}") : ""} {
+  return parse(
+    `
+    class Example ${extend ? "extends class {}" : ""} {
       ${methodName}() {${body} }
     }
-  `, { plugins: ["jsx"] });
+  `,
+    { plugins: ["jsx"] },
+  );
 }
 
 describe("arrow function conversion", () => {
   it("should convert super calls in constructors", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super(345);
       };
       super();
       () => super();
-    `, `
+    `,
+      `
       var _supercall = (..._args) => super(..._args);
 
       (function () {
@@ -59,11 +67,14 @@ describe("arrow function conversion", () => {
       });
       _supercall();
       () => _supercall();
-    `, { methodName: "constructor" });
+    `,
+      { methodName: "constructor" },
+    );
   });
 
   it("should convert super calls and this references in constructors", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super(345);
         this;
@@ -72,7 +83,8 @@ describe("arrow function conversion", () => {
       this;
       () => super();
       () => this;
-    `, `
+    `,
+      `
       var _supercall = (..._args) => _this = super(..._args),
           _this;
 
@@ -84,11 +96,14 @@ describe("arrow function conversion", () => {
       this;
       () => _supercall();
       () => this;
-    `, { methodName: "constructor", extend: true });
+    `,
+      { methodName: "constructor", extend: true },
+    );
   });
 
   it("should convert this references in constructors", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         this;
       };
@@ -96,7 +111,8 @@ describe("arrow function conversion", () => {
       this;
       () => super();
       () => this;
-    `, `
+    `,
+      `
       var _this;
 
       (function () {
@@ -106,11 +122,14 @@ describe("arrow function conversion", () => {
       this;
       () => _this = super();
       () => this;
-    `, { methodName: "constructor", extend: true });
+    `,
+      { methodName: "constructor", extend: true },
+    );
   });
 
   it("should convert this references in constructors with spec compliance", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         this;
       };
@@ -118,7 +137,8 @@ describe("arrow function conversion", () => {
       this;
       () => super();
       () => this;
-    `, `
+    `,
+      `
       var _this,
           _arrowCheckId = {};
 
@@ -131,17 +151,25 @@ describe("arrow function conversion", () => {
       this;
       () => _this = super();
       () => this;
-    `, { methodName: "constructor", extend: true, arrowOpts: { specCompliant: true } });
+    `,
+      {
+        methodName: "constructor",
+        extend: true,
+        arrowOpts: { specCompliant: true },
+      },
+    );
   });
 
   it("should convert this references in constructors without extension", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         this;
       };
       this;
       () => this;
-    `, `
+    `,
+      `
       var _this = this;
 
       (function () {
@@ -149,17 +177,21 @@ describe("arrow function conversion", () => {
       });
       this;
       () => this;
-    `, { methodName: "constructor" });
+    `,
+      { methodName: "constructor" },
+    );
   });
 
   it("should convert this references in constructors with spec compliance without extension", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         this;
       };
       this;
       () => this;
-    `, `
+    `,
+      `
       var _this = this;
 
       (function () {
@@ -169,17 +201,21 @@ describe("arrow function conversion", () => {
       }).bind(this);
       this;
       () => this;
-    `, { methodName: "constructor", arrowOpts: { specCompliant: true } });
+    `,
+      { methodName: "constructor", arrowOpts: { specCompliant: true } },
+    );
   });
 
   it("should convert this references in methods", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         this;
       };
       this;
       () => this;
-    `, `
+    `,
+      `
       var _this = this;
 
       (function () {
@@ -187,17 +223,20 @@ describe("arrow function conversion", () => {
       });
       this;
       () => this;
-    `);
+    `,
+    );
   });
 
   it("should convert this references in methods with spec compliance", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         this;
       };
       this;
       () => this;
-    `, `
+    `,
+      `
       var _this = this;
 
       (function () {
@@ -207,17 +246,21 @@ describe("arrow function conversion", () => {
       }).bind(this);
       this;
       () => this;
-    `, { arrowOpts: { specCompliant: true } });
+    `,
+      { arrowOpts: { specCompliant: true } },
+    );
   });
 
   it("should convert this references inside JSX in methods", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         <this.this this="" />;
       };
       <this.this this="" />;
       () => <this.this this="" />;
-    `, `
+    `,
+      `
       var _this = this;
 
       (function () {
@@ -225,17 +268,20 @@ describe("arrow function conversion", () => {
       });
       <this.this this="" />;
       () => <this.this this="" />;
-    `);
+    `,
+    );
   });
 
   it("should convert arguments references", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         arguments;
       };
       arguments;
       () => arguments;
-    `, `
+    `,
+      `
       var _arguments = arguments;
 
       (function () {
@@ -243,17 +289,20 @@ describe("arrow function conversion", () => {
       });
       arguments;
       () => arguments;
-    `);
+    `,
+    );
   });
 
   it("should convert new.target references", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         new.target;
       };
       new.target;
       () => new.target;
-    `, `
+    `,
+      `
       var _newtarget = new.target;
 
       (function () {
@@ -261,17 +310,20 @@ describe("arrow function conversion", () => {
       });
       new.target;
       () => new.target;
-    `);
+    `,
+    );
   });
 
   it("should convert super.prop references", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         var tmp = super.foo;
       };
       super.foo;
       () => super.foo;
-    `, `
+    `,
+      `
       var _superprop_getFoo = () => super.foo;
 
       (function () {
@@ -279,17 +331,20 @@ describe("arrow function conversion", () => {
       });
       super.foo;
       () => super.foo;
-    `);
+    `,
+    );
   });
 
   it("should convert super[prop] references", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         var tmp = super[foo];
       };
       super[foo];
       () => super[foo];
-    `, `
+    `,
+      `
       var _superprop_get = _prop => super[_prop];
 
       (function () {
@@ -297,17 +352,20 @@ describe("arrow function conversion", () => {
       });
       super[foo];
       () => super[foo];
-    `);
+    `,
+    );
   });
 
   it("should convert super.prop assignment", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super.foo = 4;
       };
       super.foo = 4;
       () => super.foo = 4;
-    `, `
+    `,
+      `
       var _superprop_setFoo = _value => super.foo = _value;
 
       (function () {
@@ -315,17 +373,20 @@ describe("arrow function conversion", () => {
       });
       super.foo = 4;
       () => super.foo = 4;
-    `);
+    `,
+    );
   });
 
   it("should convert super[prop] assignment", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super[foo] = 4;
       };
       super[foo] = 4;
       () => super[foo] = 4;
-    `, `
+    `,
+      `
       var _superprop_set = (_prop, _value) => super[_prop] = _value;
 
       (function () {
@@ -333,17 +394,20 @@ describe("arrow function conversion", () => {
       });
       super[foo] = 4;
       () => super[foo] = 4;
-    `);
+    `,
+    );
   });
 
   it("should convert super.prop operator assign", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super.foo **= 4;
       };
       super.foo **= 4;
       () => super.foo **= 4;
-    `, `
+    `,
+      `
       var _superprop_setFoo = _value => super.foo = _value,
           _superprop_getFoo = () => super.foo;
 
@@ -352,17 +416,20 @@ describe("arrow function conversion", () => {
       });
       super.foo **= 4;
       () => super.foo **= 4;
-    `);
+    `,
+    );
   });
 
   it("should convert super[prop] operator assign", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super[foo] **= 4;
       };
       super[foo] **= 4;
       () => super[foo] **= 4;
-    `, `
+    `,
+      `
       var _superprop_set = (_prop, _value) => super[_prop] = _value,
           _superprop_get = _prop2 => super[_prop2];
 
@@ -373,17 +440,20 @@ describe("arrow function conversion", () => {
       });
       super[foo] **= 4;
       () => super[foo] **= 4;
-    `);
+    `,
+    );
   });
 
   it("should convert super.prop prefix update", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         ++super.foo;
       };
       ++super.foo;
       () => ++super.foo;
-    `, `
+    `,
+      `
       var _superprop_getFoo = () => super.foo,
           _superprop_setFoo = _value => super.foo = _value;
 
@@ -394,17 +464,20 @@ describe("arrow function conversion", () => {
       });
       ++super.foo;
       () => ++super.foo;
-    `);
+    `,
+    );
   });
 
   it("should convert super[prop] prefix update", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         ++super[foo];
       };
       ++super[foo];
       () => ++super[foo];
-    `, `
+    `,
+      `
       var _superprop_get = _prop2 => super[_prop2],
           _superprop_set = (_prop3, _value) => super[_prop3] = _value;
 
@@ -415,17 +488,20 @@ describe("arrow function conversion", () => {
       });
       ++super[foo];
       () => ++super[foo];
-    `);
+    `,
+    );
   });
 
   it("should convert super.prop suffix update", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super.foo++;
       };
       super.foo++;
       () => super.foo++;
-    `, `
+    `,
+      `
       var _superprop_getFoo = () => super.foo,
           _superprop_setFoo = _value => super.foo = _value;
 
@@ -436,17 +512,20 @@ describe("arrow function conversion", () => {
       });
       super.foo++;
       () => super.foo++;
-    `);
+    `,
+    );
   });
 
   it("should convert super[prop] suffix update", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super[foo]++;
       };
       super[foo]++;
       () => super[foo]++;
-    `, `
+    `,
+      `
       var _superprop_get = _prop2 => super[_prop2],
           _superprop_set = (_prop3, _value) => super[_prop3] = _value;
 
@@ -457,17 +536,20 @@ describe("arrow function conversion", () => {
       });
       super[foo]++;
       () => super[foo]++;
-    `);
+    `,
+    );
   });
 
   it("should convert super.prop() calls", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super.foo();
       };
       super.foo();
       () => super.foo();
-    `, `
+    `,
+      `
       var _superprop_callFoo = (..._args) => super.foo(..._args);
 
       (function () {
@@ -475,17 +557,20 @@ describe("arrow function conversion", () => {
       });
       super.foo();
       () => super.foo();
-    `);
+    `,
+    );
   });
 
   it("should convert super[prop]() calls", () => {
-    assertConversion(`
+    assertConversion(
+      `
       () => {
         super[foo]();
       };
       super[foo]();
       () => super[foo]();
-    `, `
+    `,
+      `
       var _superprop_call = (_prop, ..._args) => super[_prop](..._args);
 
       (function () {
@@ -493,6 +578,7 @@ describe("arrow function conversion", () => {
       });
       super[foo]();
       () => super[foo]();
-    `);
+    `,
+    );
   });
 });
diff --git a/packages/babel-traverse/test/evaluation.js b/packages/babel-traverse/test/evaluation.js
index 056003fa5b..89b0cd29a8 100644
--- a/packages/babel-traverse/test/evaluation.js
+++ b/packages/babel-traverse/test/evaluation.js
@@ -6,7 +6,7 @@ function getPath(code) {
   const ast = parse(code);
   let path;
   traverse(ast, {
-    Program: function (_path) {
+    Program: function(_path) {
       path = _path;
       _path.stop();
     },
@@ -14,104 +14,132 @@ function getPath(code) {
   return path;
 }
 
-describe("evaluation", function () {
-  describe("evaluateTruthy", function () {
-    it("it should work with null", function () {
+describe("evaluation", function() {
+  describe("evaluateTruthy", function() {
+    it("it should work with null", function() {
       assert.strictEqual(
         getPath("false || a.length === 0;").get("body")[0].evaluateTruthy(),
-        undefined
+        undefined,
       );
     });
 
-    it("it should not mistake lack of confidence for falsy", function () {
+    it("it should not mistake lack of confidence for falsy", function() {
       assert.strictEqual(
         getPath("foo || 'bar'").get("body")[0].evaluate().value,
-        undefined
+        undefined,
       );
     });
   });
 
-  it("should bail out on recursive evaluation", function () {
+  it("should bail out on recursive evaluation", function() {
     assert.strictEqual(
       getPath("function fn(a) { var g = a ? 1 : 2, a = g * this.foo; }")
-        .get("body.0.body.body.0.declarations.1.init").evaluate().confident,
-      false
+        .get("body.0.body.body.0.declarations.1.init")
+        .evaluate().confident,
+      false,
     );
   });
 
-  it("should work with repeated, indeterminate identifiers", function () {
+  it("should work with repeated, indeterminate identifiers", function() {
     assert.strictEqual(
-      getPath("var num = foo(); (num > 0 && num < 100);").get("body")[1].evaluateTruthy(),
-      undefined
+      getPath("var num = foo(); (num > 0 && num < 100);")
+        .get("body")[1]
+        .evaluateTruthy(),
+      undefined,
     );
   });
 
-  it("should work with repeated, determinate identifiers", function () {
+  it("should work with repeated, determinate identifiers", function() {
     assert.strictEqual(
-      getPath("var num = 5; (num > 0 && num < 100);").get("body")[1].evaluateTruthy(),
-      true
+      getPath("var num = 5; (num > 0 && num < 100);")
+        .get("body")[1]
+        .evaluateTruthy(),
+      true,
     );
   });
 
-  it("should deopt when var is redeclared in the same scope", function () {
+  it("should deopt when var is redeclared in the same scope", function() {
     assert.strictEqual(
       getPath("var x = 2; var y = x + 2; { var x = 3 }")
-        .get("body.1.declarations.0.init").evaluate().confident,
-      false
+        .get("body.1.declarations.0.init")
+        .evaluate().confident,
+      false,
     );
   });
 
-  it("it should not deopt vars in different scope", function () {
-    const input = "var a = 5; function x() { var a = 5; var b = a + 1; } var b = a + 2";
+  it("it should not deopt vars in different scope", function() {
+    const input =
+      "var a = 5; function x() { var a = 5; var b = a + 1; } var b = a + 2";
     assert.strictEqual(
-      getPath(input).get("body.1.body.body.1.declarations.0.init").evaluate().value,
-      6
+      getPath(input).get("body.1.body.body.1.declarations.0.init").evaluate()
+        .value,
+      6,
     );
     assert.strictEqual(
       getPath(input).get("body.2.declarations.0.init").evaluate().value,
-      7
+      7,
     );
   });
 
-  it("it should not deopt let/const inside blocks", function () {
+  it("it should not deopt let/const inside blocks", function() {
     assert.strictEqual(
       getPath("let x = 5; { let x = 1; } let y = x + 5")
-        .get("body.2.declarations.0.init").evaluate().value,
-      10
+        .get("body.2.declarations.0.init")
+        .evaluate().value,
+      10,
     );
-    const constExample = "const d = true; if (d && true || false) { const d = false; d && 5; }";
+    const constExample =
+      "const d = true; if (d && true || false) { const d = false; d && 5; }";
     assert.strictEqual(
       getPath(constExample).get("body.1.test").evaluate().value,
-      true
+      true,
     );
     assert.strictEqual(
       getPath(constExample).get("body.1.consequent.body.1").evaluate().value,
-      false
+      false,
     );
   });
 
-  it("should deopt ids that are referenced before the bindings", function () {
+  it("should deopt ids that are referenced before the bindings", function() {
     assert.strictEqual(
-      getPath("let x = y + 5; let y = 5;").get("body.0.declarations.0.init").evaluate().confident,
-      false
+      getPath("let x = y + 5; let y = 5;")
+        .get("body.0.declarations.0.init")
+        .evaluate().confident,
+      false,
     );
     assert.strictEqual(
       getPath("if (typeof x === 'undefined') var x = {}")
-        .get("body.0.test").evaluate().confident,
-      false
+        .get("body.0.test")
+        .evaluate().confident,
+      false,
     );
   });
 
   it("should evaluate undefined, NaN and Infinity", () => {
-    assert.strictEqual(getPath("undefined").get("body.0.expression").evaluate().confident, true);
-    assert.strictEqual(getPath("NaN").get("body.0.expression").evaluate().confident, true);
-    assert.strictEqual(getPath("Infinity").get("body.0.expression").evaluate().confident, true);
+    assert.strictEqual(
+      getPath("undefined").get("body.0.expression").evaluate().confident,
+      true,
+    );
+    assert.strictEqual(
+      getPath("NaN").get("body.0.expression").evaluate().confident,
+      true,
+    );
+    assert.strictEqual(
+      getPath("Infinity").get("body.0.expression").evaluate().confident,
+      true,
+    );
   });
 
   it("should deopt redefined primitives - undefined, NaN and Infinity", () => {
-    const eval_undef = getPath("let undefined; undefined;").get("body.1.expression").evaluate();
-    const eval_nan = getPath("let NaN; NaN;").get("body.1.expression").evaluate();
-    const eval_inf = getPath("let Infinity; Infinity;").get("body.1.expression").evaluate();
+    const eval_undef = getPath("let undefined; undefined;")
+      .get("body.1.expression")
+      .evaluate();
+    const eval_nan = getPath("let NaN; NaN;")
+      .get("body.1.expression")
+      .evaluate();
+    const eval_inf = getPath("let Infinity; Infinity;")
+      .get("body.1.expression")
+      .evaluate();
     assert.strictEqual(eval_undef.confident, false);
     assert.strictEqual(eval_nan.confident, false);
     assert.strictEqual(eval_inf.confident, false);
@@ -120,15 +148,15 @@ describe("evaluation", function () {
     assert.strictEqual(eval_undef.deopt.parentPath.node.kind, "let");
   });
 
-  it("should work with String.raw", function () {
+  it("should work with String.raw", function() {
     assert.strictEqual(
       getPath("String.raw`\\d`").get("body")[0].evaluate().value,
-      "\\d"
+      "\\d",
     );
 
     assert.strictEqual(
       getPath("`${String.raw`\\d`}`").get("body")[0].evaluate().value,
-      "\\d"
+      "\\d",
     );
   });
 });
diff --git a/packages/babel-traverse/test/family.js b/packages/babel-traverse/test/family.js
index ffaa90e385..7a5821b581 100644
--- a/packages/babel-traverse/test/family.js
+++ b/packages/babel-traverse/test/family.js
@@ -2,10 +2,13 @@ import traverse from "../lib";
 import assert from "assert";
 import { parse } from "babylon";
 
-describe("path/family", function () {
-  describe("getBindingIdentifiers", function () {
+describe("path/family", function() {
+  describe("getBindingIdentifiers", function() {
     const ast = parse("var a = 1, {b} = c, [d] = e; function f() {}");
-    let nodes = {}, paths = {}, outerNodes = {}, outerPaths = {};
+    let nodes = {},
+      paths = {},
+      outerNodes = {},
+      outerPaths = {};
     traverse(ast, {
       VariableDeclaration(path) {
         nodes = path.getBindingIdentifiers();
@@ -17,46 +20,56 @@ describe("path/family", function () {
       },
     });
 
-    it("should contain keys of nodes in paths", function () {
-      Object.keys(nodes).forEach((id) => {
+    it("should contain keys of nodes in paths", function() {
+      Object.keys(nodes).forEach(id => {
         assert.strictEqual(hop(paths, id), true, "Node's keys exists in paths");
       });
     });
 
-    it("should contain outer bindings", function () {
-      Object.keys(outerNodes).forEach((id) => {
+    it("should contain outer bindings", function() {
+      Object.keys(outerNodes).forEach(id => {
         assert.strictEqual(hop(outerPaths, id), true, "Has same outer keys");
       });
     });
 
-    it("should return paths", function () {
-      Object.keys(paths).forEach((id) => {
-        assert.strictEqual(!!paths[id].node, true, "Has a property node that's not falsy");
+    it("should return paths", function() {
+      Object.keys(paths).forEach(id => {
+        assert.strictEqual(
+          !!paths[id].node,
+          true,
+          "Has a property node that's not falsy",
+        );
         assert.strictEqual(paths[id].type, paths[id].node.type, "type matches");
       });
 
-      Object.keys(outerPaths).forEach((id) => {
+      Object.keys(outerPaths).forEach(id => {
         assert.strictEqual(!!outerPaths[id].node, true, "has property node");
-        assert.strictEqual(outerPaths[id].type, outerPaths[id].node.type, "type matches");
+        assert.strictEqual(
+          outerPaths[id].type,
+          outerPaths[id].node.type,
+          "type matches",
+        );
       });
     });
 
-    it("should match paths and nodes returned for the same ast", function () {
-      Object.keys(nodes).forEach((id) => {
+    it("should match paths and nodes returned for the same ast", function() {
+      Object.keys(nodes).forEach(id => {
         assert.strictEqual(nodes[id], paths[id].node, "Nodes match");
       });
     });
 
-    it("should match paths and nodes returned for outer Bindings", function () {
-      Object.keys(outerNodes).forEach((id) => {
+    it("should match paths and nodes returned for outer Bindings", function() {
+      Object.keys(outerNodes).forEach(id => {
         assert.strictEqual(outerNodes[id], outerPaths[id].node, "nodes match");
       });
     });
-
   });
-  describe("getSibling", function () {
-    const ast = parse("var a = 1, {b} = c, [d] = e; function f() {} function g() {}");
-    let sibling = {}, lastSibling = {};
+  describe("getSibling", function() {
+    const ast = parse(
+      "var a = 1, {b} = c, [d] = e; function f() {} function g() {}",
+    );
+    let sibling = {},
+      lastSibling = {};
     traverse(ast, {
       VariableDeclaration(path) {
         sibling = path.getSibling(path.key);
@@ -64,18 +77,26 @@ describe("path/family", function () {
       },
     });
 
-    it("should return traverse sibling nodes", function () {
+    it("should return traverse sibling nodes", function() {
       assert.ok(sibling.getNextSibling().node, "has property node");
       assert.ok(lastSibling.getPrevSibling().node, "has property node");
       assert.equal(!!sibling.getPrevSibling().node, false, "out of scope");
       assert.equal(!!lastSibling.getNextSibling().node, false, "out of scope");
     });
 
-    it("should return all preceding and succeeding sibling nodes", function () {
+    it("should return all preceding and succeeding sibling nodes", function() {
       assert.ok(sibling.getAllNextSiblings().length, "Has next sibling");
       assert.ok(lastSibling.getAllPrevSiblings().length, "Has prev sibling");
-      assert.equal(sibling.getAllNextSiblings().length, 2, "Has 2 succeeding sibling");
-      assert.equal(lastSibling.getAllPrevSiblings().length, 2, "Has 2 preceeding sibling");
+      assert.equal(
+        sibling.getAllNextSiblings().length,
+        2,
+        "Has 2 succeeding sibling",
+      );
+      assert.equal(
+        lastSibling.getAllPrevSiblings().length,
+        2,
+        "Has 2 preceeding sibling",
+      );
     });
   });
 });
diff --git a/packages/babel-traverse/test/inference.js b/packages/babel-traverse/test/inference.js
index 7fe06584d5..34513f069d 100644
--- a/packages/babel-traverse/test/inference.js
+++ b/packages/babel-traverse/test/inference.js
@@ -7,7 +7,7 @@ function getPath(code) {
   const ast = parse(code, { plugins: ["flow", "asyncGenerators"] });
   let path;
   traverse(ast, {
-    Program: function (_path) {
+    Program: function(_path) {
       path = _path;
       _path.stop();
     },
@@ -15,10 +15,12 @@ function getPath(code) {
   return path;
 }
 
-describe("inference", function () {
-  describe("baseTypeStrictlyMatches", function () {
-    it("it should work with null", function () {
-      const path = getPath("var x = null; x === null").get("body")[1].get("expression");
+describe("inference", function() {
+  describe("baseTypeStrictlyMatches", function() {
+    it("it should work with null", function() {
+      const path = getPath("var x = null; x === null")
+        .get("body")[1]
+        .get("expression");
       const left = path.get("left");
       const right = path.get("right");
       const strictMatch = left.baseTypeStrictlyMatches(right);
@@ -26,8 +28,10 @@ describe("inference", function () {
       assert.ok(strictMatch, "null should be equal to null");
     });
 
-    it("it should work with numbers", function () {
-      const path = getPath("var x = 1; x === 2").get("body")[1].get("expression");
+    it("it should work with numbers", function() {
+      const path = getPath("var x = 1; x === 2")
+        .get("body")[1]
+        .get("expression");
       const left = path.get("left");
       const right = path.get("right");
       const strictMatch = left.baseTypeStrictlyMatches(right);
@@ -35,9 +39,10 @@ describe("inference", function () {
       assert.ok(strictMatch, "number should be equal to number");
     });
 
-    it("it should bail when type changes", function () {
+    it("it should bail when type changes", function() {
       const path = getPath("var x = 1; if (foo) x = null;else x = 3; x === 2")
-        .get("body")[2].get("expression");
+        .get("body")[2]
+        .get("expression");
       const left = path.get("left");
       const right = path.get("right");
 
@@ -46,8 +51,10 @@ describe("inference", function () {
       assert.ok(!strictMatch, "type might change in if statement");
     });
 
-    it("it should differentiate between null and undefined", function () {
-      const path = getPath("var x; x === null").get("body")[1].get("expression");
+    it("it should differentiate between null and undefined", function() {
+      const path = getPath("var x; x === null")
+        .get("body")[1]
+        .get("expression");
       const left = path.get("left");
       const right = path.get("right");
       const strictMatch = left.baseTypeStrictlyMatches(right);
@@ -55,125 +62,202 @@ describe("inference", function () {
       assert.ok(!strictMatch, "null should not match undefined");
     });
   });
-  describe("getTypeAnnotation", function () {
-    it("should infer from type cast", function () {
+  describe("getTypeAnnotation", function() {
+    it("should infer from type cast", function() {
       const path = getPath("(x: number)").get("body")[0].get("expression");
-      assert.ok(t.isNumberTypeAnnotation(path.getTypeAnnotation()), "should be number");
-
+      assert.ok(
+        t.isNumberTypeAnnotation(path.getTypeAnnotation()),
+        "should be number",
+      );
     });
-    it("should infer string from template literal", function () {
+    it("should infer string from template literal", function() {
       const path = getPath("`hey`").get("body")[0].get("expression");
-      assert.ok(t.isStringTypeAnnotation(path.getTypeAnnotation()), "should be string");
+      assert.ok(
+        t.isStringTypeAnnotation(path.getTypeAnnotation()),
+        "should be string",
+      );
     });
-    it("should infer number from +x", function () {
+    it("should infer number from +x", function() {
       const path = getPath("+x").get("body")[0].get("expression");
-      assert.ok(t.isNumberTypeAnnotation(path.getTypeAnnotation()), "should be number");
+      assert.ok(
+        t.isNumberTypeAnnotation(path.getTypeAnnotation()),
+        "should be number",
+      );
     });
-    it("should infer T from new T", function () {
+    it("should infer T from new T", function() {
       const path = getPath("new T").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
-      assert.ok(t.isGenericTypeAnnotation(type) && type.id.name === "T", "should be T");
+      assert.ok(
+        t.isGenericTypeAnnotation(type) && type.id.name === "T",
+        "should be T",
+      );
     });
-    it("should infer number from ++x", function () {
+    it("should infer number from ++x", function() {
       const path = getPath("++x").get("body")[0].get("expression");
-      assert.ok(t.isNumberTypeAnnotation(path.getTypeAnnotation()), "should be number");
+      assert.ok(
+        t.isNumberTypeAnnotation(path.getTypeAnnotation()),
+        "should be number",
+      );
     });
-    it("should infer number from --x", function () {
+    it("should infer number from --x", function() {
       const path = getPath("--x").get("body")[0].get("expression");
-      assert.ok(t.isNumberTypeAnnotation(path.getTypeAnnotation()), "should be number");
+      assert.ok(
+        t.isNumberTypeAnnotation(path.getTypeAnnotation()),
+        "should be number",
+      );
     });
-    it("should infer void from void x", function () {
+    it("should infer void from void x", function() {
       const path = getPath("void x").get("body")[0].get("expression");
-      assert.ok(t.isVoidTypeAnnotation(path.getTypeAnnotation()), "should be void");
+      assert.ok(
+        t.isVoidTypeAnnotation(path.getTypeAnnotation()),
+        "should be void",
+      );
     });
-    it("should infer string from typeof x", function () {
+    it("should infer string from typeof x", function() {
       const path = getPath("typeof x").get("body")[0].get("expression");
-      assert.ok(t.isStringTypeAnnotation(path.getTypeAnnotation()), "should be string");
+      assert.ok(
+        t.isStringTypeAnnotation(path.getTypeAnnotation()),
+        "should be string",
+      );
     });
-    it("should infer boolean from !x", function () {
+    it("should infer boolean from !x", function() {
       const path = getPath("!x").get("body")[0].get("expression");
-      assert.ok(t.isBooleanTypeAnnotation(path.getTypeAnnotation()), "should be boolean");
+      assert.ok(
+        t.isBooleanTypeAnnotation(path.getTypeAnnotation()),
+        "should be boolean",
+      );
     });
-    it("should infer type of sequence expression", function () {
+    it("should infer type of sequence expression", function() {
       const path = getPath("a,1").get("body")[0].get("expression");
-      assert.ok(t.isNumberTypeAnnotation(path.getTypeAnnotation()), "should be number");
+      assert.ok(
+        t.isNumberTypeAnnotation(path.getTypeAnnotation()),
+        "should be number",
+      );
     });
-    it("should infer type of logical expression", function () {
+    it("should infer type of logical expression", function() {
       const path = getPath("'a' && 1").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
       assert.ok(t.isUnionTypeAnnotation(type), "should be a union");
-      assert.ok(t.isStringTypeAnnotation(type.types[0]), "first type in union should be string");
-      assert.ok(t.isNumberTypeAnnotation(type.types[1]), "second type in union should be number");
+      assert.ok(
+        t.isStringTypeAnnotation(type.types[0]),
+        "first type in union should be string",
+      );
+      assert.ok(
+        t.isNumberTypeAnnotation(type.types[1]),
+        "second type in union should be number",
+      );
     });
-    it("should infer type of conditional expression", function () {
+    it("should infer type of conditional expression", function() {
       const path = getPath("q ? true : 0").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
       assert.ok(t.isUnionTypeAnnotation(type), "should be a union");
-      assert.ok(t.isBooleanTypeAnnotation(type.types[0]), "first type in union should be boolean");
-      assert.ok(t.isNumberTypeAnnotation(type.types[1]), "second type in union should be number");
+      assert.ok(
+        t.isBooleanTypeAnnotation(type.types[0]),
+        "first type in union should be boolean",
+      );
+      assert.ok(
+        t.isNumberTypeAnnotation(type.types[1]),
+        "second type in union should be number",
+      );
     });
-    it("should infer RegExp from RegExp literal", function () {
+    it("should infer RegExp from RegExp literal", function() {
       const path = getPath("/.+/").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
-      assert.ok(t.isGenericTypeAnnotation(type) && type.id.name === "RegExp", "should be RegExp");
+      assert.ok(
+        t.isGenericTypeAnnotation(type) && type.id.name === "RegExp",
+        "should be RegExp",
+      );
     });
-    it("should infer Object from object expression", function () {
+    it("should infer Object from object expression", function() {
       const path = getPath("({ a: 5 })").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
-      assert.ok(t.isGenericTypeAnnotation(type) && type.id.name === "Object", "should be Object");
+      assert.ok(
+        t.isGenericTypeAnnotation(type) && type.id.name === "Object",
+        "should be Object",
+      );
     });
-    it("should infer Array from array expression", function () {
+    it("should infer Array from array expression", function() {
       const path = getPath("[ 5 ]").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
-      assert.ok(t.isGenericTypeAnnotation(type) && type.id.name === "Array", "should be Array");
+      assert.ok(
+        t.isGenericTypeAnnotation(type) && type.id.name === "Array",
+        "should be Array",
+      );
     });
-    it("should infer Function from function", function () {
-      const path = getPath("(function (): string {})").get("body")[0].get("expression");
+    it("should infer Function from function", function() {
+      const path = getPath("(function (): string {})")
+        .get("body")[0]
+        .get("expression");
       const type = path.getTypeAnnotation();
-      assert.ok(t.isGenericTypeAnnotation(type) && type.id.name === "Function", "should be Function");
+      assert.ok(
+        t.isGenericTypeAnnotation(type) && type.id.name === "Function",
+        "should be Function",
+      );
     });
-    it("should infer call return type using function", function () {
-      const path = getPath("(function (): string {})()").get("body")[0].get("expression");
+    it("should infer call return type using function", function() {
+      const path = getPath("(function (): string {})()")
+        .get("body")[0]
+        .get("expression");
       const type = path.getTypeAnnotation();
       assert.ok(t.isStringTypeAnnotation(type), "should be string");
     });
-    it("should infer call return type using async function", function () {
-      const path = getPath("(async function (): string {})()").get("body")[0].get("expression");
+    it("should infer call return type using async function", function() {
+      const path = getPath("(async function (): string {})()")
+        .get("body")[0]
+        .get("expression");
       const type = path.getTypeAnnotation();
-      assert.ok(t.isGenericTypeAnnotation(type) && type.id.name === "Promise", "should be Promise");
+      assert.ok(
+        t.isGenericTypeAnnotation(type) && type.id.name === "Promise",
+        "should be Promise",
+      );
     });
-    it("should infer call return type using async generator function", function () {
-      const path = getPath("(async function * (): string {})()").get("body")[0].get("expression");
+    it("should infer call return type using async generator function", function() {
+      const path = getPath("(async function * (): string {})()")
+        .get("body")[0]
+        .get("expression");
       const type = path.getTypeAnnotation();
-      assert.ok(t.isGenericTypeAnnotation(type) && type.id.name === "AsyncIterator",
-        "should be AsyncIterator");
+      assert.ok(
+        t.isGenericTypeAnnotation(type) && type.id.name === "AsyncIterator",
+        "should be AsyncIterator",
+      );
     });
-    it("should infer number from x/y", function () {
+    it("should infer number from x/y", function() {
       const path = getPath("x/y").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
       assert.ok(t.isNumberTypeAnnotation(type), "should be number");
     });
-    it("should infer boolean from x instanceof y", function () {
+    it("should infer boolean from x instanceof y", function() {
       const path = getPath("x instanceof y").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
       assert.ok(t.isBooleanTypeAnnotation(type), "should be boolean");
     });
-    it("should infer number from 1 + 2", function () {
+    it("should infer number from 1 + 2", function() {
       const path = getPath("1 + 2").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
       assert.ok(t.isNumberTypeAnnotation(type), "should be number");
     });
-    it("should infer string|number from x + y", function () {
+    it("should infer string|number from x + y", function() {
       const path = getPath("x + y").get("body")[0].get("expression");
       const type = path.getTypeAnnotation();
       assert.ok(t.isUnionTypeAnnotation(type), "should be a union");
-      assert.ok(t.isStringTypeAnnotation(type.types[0]), "first type in union should be string");
-      assert.ok(t.isNumberTypeAnnotation(type.types[1]), "second type in union should be number");
+      assert.ok(
+        t.isStringTypeAnnotation(type.types[0]),
+        "first type in union should be string",
+      );
+      assert.ok(
+        t.isNumberTypeAnnotation(type.types[1]),
+        "second type in union should be number",
+      );
     });
-    it("should infer type of tagged template literal", function () {
-      const path = getPath("(function (): RegExp {}) `hey`").get("body")[0].get("expression");
+    it("should infer type of tagged template literal", function() {
+      const path = getPath("(function (): RegExp {}) `hey`")
+        .get("body")[0]
+        .get("expression");
       const type = path.getTypeAnnotation();
-      assert.ok(t.isGenericTypeAnnotation(type) && type.id.name === "RegExp", "should be RegExp");
+      assert.ok(
+        t.isGenericTypeAnnotation(type) && type.id.name === "RegExp",
+        "should be RegExp",
+      );
     });
   });
 });
diff --git a/packages/babel-traverse/test/removal.js b/packages/babel-traverse/test/removal.js
index a2a43acd34..371e2b1cbc 100644
--- a/packages/babel-traverse/test/removal.js
+++ b/packages/babel-traverse/test/removal.js
@@ -7,7 +7,7 @@ function getPath(code) {
   const ast = parse(code);
   let path;
   traverse(ast, {
-    Program: function (_path) {
+    Program: function(_path) {
       path = _path;
       _path.stop();
     },
@@ -20,15 +20,19 @@ function generateCode(path) {
   return generate(path.node).code;
 }
 
-describe("removal", function () {
-  describe("ArrowFunction", function () {
-    it("remove body", function () {
+describe("removal", function() {
+  describe("ArrowFunction", function() {
+    it("remove body", function() {
       const rootPath = getPath("x = () => b;");
       const path = rootPath.get("body")[0].get("expression").get("right");
       const body = path.get("body");
       body.remove();
 
-      assert.equal(generateCode(rootPath), "x = () => {};", "body should be replaced with BlockStatement");
+      assert.equal(
+        generateCode(rootPath),
+        "x = () => {};",
+        "body should be replaced with BlockStatement",
+      );
     });
   });
 });
diff --git a/packages/babel-traverse/test/replacement.js b/packages/babel-traverse/test/replacement.js
index f2d233d62f..6bcf2d3da5 100644
--- a/packages/babel-traverse/test/replacement.js
+++ b/packages/babel-traverse/test/replacement.js
@@ -4,21 +4,25 @@ import { parse } from "babylon";
 import * as t from "babel-types";
 import { expect } from "chai";
 
-describe("path/replacement", function () {
-  describe("replaceWith", function () {
+describe("path/replacement", function() {
+  describe("replaceWith", function() {
     it("replaces declaration in ExportDefaultDeclaration node", function() {
-      const ast = parse("export default function() {};", { sourceType: "module" });
+      const ast = parse("export default function() {};", {
+        sourceType: "module",
+      });
       traverse(ast, {
         FunctionDeclaration(path) {
-          path.replaceWith(t.arrayExpression([
-            t.functionExpression(
-              path.node.id,
-              path.node.params,
-              path.node.body,
-              path.node.generator,
-              path.node.async
-            ),
-          ]));
+          path.replaceWith(
+            t.arrayExpression([
+              t.functionExpression(
+                path.node.id,
+                path.node.params,
+                path.node.body,
+                path.node.generator,
+                path.node.async,
+              ),
+            ]),
+          );
         },
       });
 
@@ -33,7 +37,9 @@ describe("path/replacement", function () {
             path.replaceWith(t.identifier("a"));
           },
         });
-      }).to.throw(/You can only replace a Program root node with another Program node/);
+      }).to.throw(
+        /You can only replace a Program root node with another Program node/,
+      );
     });
 
     it("throws error when used with an array of nodes", function() {
@@ -49,12 +55,14 @@ describe("path/replacement", function () {
           },
         });
       }).to.throw(
-        /Don't use `path\.replaceWith\(\)` with an array of nodes, use `path\.replaceWithMultiple\(\)`/
+        /Don't use `path\.replaceWith\(\)` with an array of nodes, use `path\.replaceWithMultiple\(\)`/,
       );
     });
 
     it("throws error when used with source string", function() {
-      const ast = parse("(function() { var x = 3; var y = 17; var c = x + y; })();");
+      const ast = parse(
+        "(function() { var x = 3; var y = 17; var c = x + y; })();",
+      );
       expect(function() {
         traverse(ast, {
           BinaryExpression(path) {
@@ -62,7 +70,7 @@ describe("path/replacement", function () {
           },
         });
       }).to.throw(
-        /Don't use `path\.replaceWith\(\)` with a source string, use `path\.replaceWithSourceString\(\)`/
+        /Don't use `path\.replaceWith\(\)` with a source string, use `path\.replaceWithSourceString\(\)`/,
       );
     });
 
@@ -75,9 +83,7 @@ describe("path/replacement", function () {
             path.replaceWith(t.identifier("p"));
           },
         });
-      }).to.throw(
-        /You can't replace this node, we've already removed it/,
-      );
+      }).to.throw(/You can't replace this node, we've already removed it/);
     });
 
     it("throws error when passed a falsy value", function() {
@@ -92,6 +98,5 @@ describe("path/replacement", function () {
         /You passed `path\.replaceWith\(\)` a falsy node, use `path\.remove\(\)` instead/,
       );
     });
-
   });
 });
diff --git a/packages/babel-traverse/test/scope.js b/packages/babel-traverse/test/scope.js
index d715d74ebc..1017f85f88 100644
--- a/packages/babel-traverse/test/scope.js
+++ b/packages/babel-traverse/test/scope.js
@@ -6,7 +6,7 @@ function getPath(code) {
   const ast = parse(code);
   let path;
   traverse(ast, {
-    Program: function (_path) {
+    Program: function(_path) {
       path = _path;
       _path.stop();
     },
@@ -27,66 +27,116 @@ function getIdentifierPath(code) {
   return nodePath;
 }
 
-describe("scope", function () {
-  describe("binding paths", function () {
-    it("function declaration id", function () {
-      assert.ok(getPath("function foo() {}")
-        .scope.getBinding("foo").path.type === "FunctionDeclaration");
+describe("scope", function() {
+  describe("binding paths", function() {
+    it("function declaration id", function() {
+      assert.ok(
+        getPath("function foo() {}").scope.getBinding("foo").path.type ===
+          "FunctionDeclaration",
+      );
     });
 
-    it("function expression id", function () {
-      assert.ok(getPath("(function foo() {})").get("body")[0].get("expression")
-        .scope.getBinding("foo").path.type === "FunctionExpression");
+    it("function expression id", function() {
+      assert.ok(
+        getPath("(function foo() {})")
+          .get("body")[0]
+          .get("expression")
+          .scope.getBinding("foo").path.type === "FunctionExpression",
+      );
     });
 
-    it("function param", function () {
-      assert.ok(getPath("(function (foo) {})").get("body")[0].get("expression")
-        .scope.getBinding("foo").path.type === "Identifier");
+    it("function param", function() {
+      assert.ok(
+        getPath("(function (foo) {})")
+          .get("body")[0]
+          .get("expression")
+          .scope.getBinding("foo").path.type === "Identifier",
+      );
     });
 
-    it("variable declaration", function () {
-      assert.ok(getPath("var foo = null;")
-        .scope.getBinding("foo").path.type === "VariableDeclarator");
-      assert.ok(getPath("var { foo } = null;")
-        .scope.getBinding("foo").path.type === "VariableDeclarator");
-      assert.ok(getPath("var [ foo ] = null;")
-        .scope.getBinding("foo").path.type === "VariableDeclarator");
-      assert.ok(getPath("var { bar: [ foo ] } = null;")
-        .scope.getBinding("foo").path.type === "VariableDeclarator");
+    it("variable declaration", function() {
+      assert.ok(
+        getPath("var foo = null;").scope.getBinding("foo").path.type ===
+          "VariableDeclarator",
+      );
+      assert.ok(
+        getPath("var { foo } = null;").scope.getBinding("foo").path.type ===
+          "VariableDeclarator",
+      );
+      assert.ok(
+        getPath("var [ foo ] = null;").scope.getBinding("foo").path.type ===
+          "VariableDeclarator",
+      );
+      assert.ok(
+        getPath("var { bar: [ foo ] } = null;").scope.getBinding("foo").path
+          .type === "VariableDeclarator",
+      );
     });
 
-    it("purity", function () {
-      assert.ok(getPath("({ x: 1 })").get("body")[0].get("expression").isPure());
+    it("purity", function() {
+      assert.ok(
+        getPath("({ x: 1 })").get("body")[0].get("expression").isPure(),
+      );
     });
 
-    test("label", function () {
-      assert.strictEqual(getPath("foo: { }").scope.getBinding("foo"), undefined);
-      assert.strictEqual(getPath("foo: { }").scope.getLabel("foo").type, "LabeledStatement");
-      assert.strictEqual(getPath("foo: { }").scope.getLabel("toString"), undefined);
+    test("label", function() {
+      assert.strictEqual(
+        getPath("foo: { }").scope.getBinding("foo"),
+        undefined,
+      );
+      assert.strictEqual(
+        getPath("foo: { }").scope.getLabel("foo").type,
+        "LabeledStatement",
+      );
+      assert.strictEqual(
+        getPath("foo: { }").scope.getLabel("toString"),
+        undefined,
+      );
 
-      assert.strictEqual(getPath(`
+      assert.strictEqual(
+        getPath(
+          `
         foo: { }
-      `).scope.generateUid("foo"), "_foo");
+      `,
+        ).scope.generateUid("foo"),
+        "_foo",
+      );
     });
 
-    test("generateUid collision check with labels", function () {
-      assert.strictEqual(getPath(`
+    test("generateUid collision check with labels", function() {
+      assert.strictEqual(
+        getPath(
+          `
         _foo: { }
-      `).scope.generateUid("foo"), "_foo2");
+      `,
+        ).scope.generateUid("foo"),
+        "_foo2",
+      );
 
-      assert.strictEqual(getPath(`
+      assert.strictEqual(
+        getPath(
+          `
         _foo: { }
         _foo1: { }
         _foo2: { }
-      `).scope.generateUid("foo"), "_foo3");
+      `,
+        ).scope.generateUid("foo"),
+        "_foo3",
+      );
     });
 
     it("reference paths", function() {
       const path = getIdentifierPath("function square(n) { return n * n}");
       const referencePaths = path.context.scope.bindings.n.referencePaths;
       assert.equal(referencePaths.length, 2);
-      assert.deepEqual(referencePaths[0].node.loc.start, { line: 1, column: 28 });
-      assert.deepEqual(referencePaths[1].node.loc.start, { line: 1, column: 32 });
+      assert.deepEqual(referencePaths[0].node.loc.start, {
+        line: 1,
+        column: 28,
+      });
+      assert.deepEqual(referencePaths[1].node.loc.start, {
+        line: 1,
+        column: 32,
+      });
     });
   });
 });
diff --git a/packages/babel-traverse/test/traverse.js b/packages/babel-traverse/test/traverse.js
index bc6c0c50f0..d2eb4638c6 100644
--- a/packages/babel-traverse/test/traverse.js
+++ b/packages/babel-traverse/test/traverse.js
@@ -3,7 +3,7 @@ import traverse from "../lib";
 import assert from "assert";
 import { parse } from "babylon";
 
-describe("traverse", function () {
+describe("traverse", function() {
   const code = `
     var foo = "bar";
     this.test = "wow";
@@ -12,7 +12,7 @@ describe("traverse", function () {
   const program = ast.program;
   const body = program.body;
 
-  it("traverse replace", function () {
+  it("traverse replace", function() {
     const replacement = {
       type: "StringLiteral",
       value: "foo",
@@ -20,7 +20,7 @@ describe("traverse", function () {
     const ast2 = cloneDeep(program);
 
     traverse(ast2, {
-      enter: function (path) {
+      enter: function(path) {
         if (path.node.type === "ThisExpression") path.replaceWith(replacement);
       },
     });
@@ -28,17 +28,24 @@ describe("traverse", function () {
     assert.equal(ast2.body[1].expression.left.object, replacement);
   });
 
-  it("traverse", function () {
+  it("traverse", function() {
     const expect = [
-      body[0], body[0].declarations[0], body[0].declarations[0].id, body[0].declarations[0].init,
-      body[1], body[1].expression, body[1].expression.left, body[1].expression.left.object,
-      body[1].expression.left.property, body[1].expression.right,
+      body[0],
+      body[0].declarations[0],
+      body[0].declarations[0].id,
+      body[0].declarations[0].init,
+      body[1],
+      body[1].expression,
+      body[1].expression.left,
+      body[1].expression.left.object,
+      body[1].expression.left.property,
+      body[1].expression.right,
     ];
 
     const actual = [];
 
     traverse(program, {
-      enter: function (path) {
+      enter: function(path) {
         actual.push(path.node);
       },
     });
@@ -46,25 +53,30 @@ describe("traverse", function () {
     assert.deepEqual(actual, expect);
   });
 
-  it("traverse falsy parent", function () {
+  it("traverse falsy parent", function() {
     traverse(null, {
-      enter: function () {
+      enter: function() {
         throw new Error("should not be ran");
       },
     });
   });
 
-  it("traverse blacklistTypes", function () {
+  it("traverse blacklistTypes", function() {
     const expect = [
-      body[0], body[0].declarations[0], body[0].declarations[0].id, body[0].declarations[0].init,
-      body[1], body[1].expression, body[1].expression.right,
+      body[0],
+      body[0].declarations[0],
+      body[0].declarations[0].id,
+      body[0].declarations[0].init,
+      body[1],
+      body[1].expression,
+      body[1].expression.right,
     ];
 
     const actual = [];
 
     traverse(program, {
       blacklist: ["MemberExpression"],
-      enter: function (path) {
+      enter: function(path) {
         actual.push(path.node);
       },
     });
@@ -72,20 +84,24 @@ describe("traverse", function () {
     assert.deepEqual(actual, expect);
   });
 
-  it("hasType", function () {
+  it("hasType", function() {
     assert.ok(traverse.hasType(ast, null, "ThisExpression"));
-    assert.ok(!traverse.hasType(ast, null, "ThisExpression", ["AssignmentExpression"]));
+    assert.ok(
+      !traverse.hasType(ast, null, "ThisExpression", ["AssignmentExpression"]),
+    );
 
     assert.ok(traverse.hasType(ast, null, "ThisExpression"));
     assert.ok(traverse.hasType(ast, null, "Program"));
 
-    assert.ok(!traverse.hasType(ast, null, "ThisExpression", ["MemberExpression"]));
+    assert.ok(
+      !traverse.hasType(ast, null, "ThisExpression", ["MemberExpression"]),
+    );
     assert.ok(!traverse.hasType(ast, null, "ThisExpression", ["Program"]));
 
     assert.ok(!traverse.hasType(ast, null, "ArrowFunctionExpression"));
   });
 
-  it("clearCache", function () {
+  it("clearCache", function() {
     const paths = [];
     const scopes = [];
     traverse(ast, {
@@ -108,13 +124,13 @@ describe("traverse", function () {
       },
     });
 
-    scopes2.forEach(function (_, i) {
+    scopes2.forEach(function(_, i) {
       assert.notStrictEqual(scopes[i], scopes2[i]);
       assert.notStrictEqual(paths[i], paths2[i]);
     });
   });
 
-  it("clearPath", function () {
+  it("clearPath", function() {
     const paths = [];
     traverse(ast, {
       enter(path) {
@@ -131,12 +147,12 @@ describe("traverse", function () {
       },
     });
 
-    paths2.forEach(function (p, i) {
+    paths2.forEach(function(p, i) {
       assert.notStrictEqual(p, paths[i]);
     });
   });
 
-  it("clearScope", function () {
+  it("clearScope", function() {
     const scopes = [];
     traverse(ast, {
       enter(path) {
@@ -155,7 +171,7 @@ describe("traverse", function () {
       },
     });
 
-    scopes2.forEach(function (p, i) {
+    scopes2.forEach(function(p, i) {
       assert.notStrictEqual(p, scopes[i]);
     });
   });
diff --git a/packages/babel-types/src/constants.js b/packages/babel-types/src/constants.js
index 84c2aec646..523a4f38a2 100644
--- a/packages/babel-types/src/constants.js
+++ b/packages/babel-types/src/constants.js
@@ -3,22 +3,54 @@
 export const STATEMENT_OR_BLOCK_KEYS = ["consequent", "body", "alternate"];
 export const FLATTENABLE_KEYS = ["body", "expressions"];
 export const FOR_INIT_KEYS = ["left", "init"];
-export const COMMENT_KEYS = ["leadingComments", "trailingComments", "innerComments"];
+export const COMMENT_KEYS = [
+  "leadingComments",
+  "trailingComments",
+  "innerComments",
+];
 
 export const LOGICAL_OPERATORS = ["||", "&&"];
 export const UPDATE_OPERATORS = ["++", "--"];
 
 export const BOOLEAN_NUMBER_BINARY_OPERATORS = [">", "<", ">=", "<="];
 export const EQUALITY_BINARY_OPERATORS = ["==", "===", "!=", "!=="];
-export const COMPARISON_BINARY_OPERATORS = [...EQUALITY_BINARY_OPERATORS, "in", "instanceof"];
-export const BOOLEAN_BINARY_OPERATORS = [...COMPARISON_BINARY_OPERATORS, ...BOOLEAN_NUMBER_BINARY_OPERATORS];
-export const NUMBER_BINARY_OPERATORS = ["-", "/", "%", "*", "**", "&", "|", ">>", ">>>", "<<", "^"];
-export const BINARY_OPERATORS = ["+", ...NUMBER_BINARY_OPERATORS, ...BOOLEAN_BINARY_OPERATORS];
+export const COMPARISON_BINARY_OPERATORS = [
+  ...EQUALITY_BINARY_OPERATORS,
+  "in",
+  "instanceof",
+];
+export const BOOLEAN_BINARY_OPERATORS = [
+  ...COMPARISON_BINARY_OPERATORS,
+  ...BOOLEAN_NUMBER_BINARY_OPERATORS,
+];
+export const NUMBER_BINARY_OPERATORS = [
+  "-",
+  "/",
+  "%",
+  "*",
+  "**",
+  "&",
+  "|",
+  ">>",
+  ">>>",
+  "<<",
+  "^",
+];
+export const BINARY_OPERATORS = [
+  "+",
+  ...NUMBER_BINARY_OPERATORS,
+  ...BOOLEAN_BINARY_OPERATORS,
+];
 
 export const BOOLEAN_UNARY_OPERATORS = ["delete", "!"];
 export const NUMBER_UNARY_OPERATORS = ["+", "-", "++", "--", "~"];
 export const STRING_UNARY_OPERATORS = ["typeof"];
-export const UNARY_OPERATORS = ["void", ...BOOLEAN_UNARY_OPERATORS, ...NUMBER_UNARY_OPERATORS, ...STRING_UNARY_OPERATORS];
+export const UNARY_OPERATORS = [
+  "void",
+  ...BOOLEAN_UNARY_OPERATORS,
+  ...NUMBER_UNARY_OPERATORS,
+  ...STRING_UNARY_OPERATORS,
+];
 
 export const INHERIT_KEYS = {
   optional: ["typeAnnotation", "typeParameters", "returnType"],
@@ -26,4 +58,6 @@ export const INHERIT_KEYS = {
 };
 
 export const BLOCK_SCOPED_SYMBOL = Symbol.for("var used to be block scoped");
-export const NOT_LOCAL_BINDING = Symbol.for("should not be considered a local binding");
+export const NOT_LOCAL_BINDING = Symbol.for(
+  "should not be considered a local binding",
+);
diff --git a/packages/babel-types/src/converters.js b/packages/babel-types/src/converters.js
index a76d6bd776..454588e7ec 100644
--- a/packages/babel-types/src/converters.js
+++ b/packages/babel-types/src/converters.js
@@ -3,15 +3,21 @@ import isRegExp from "lodash/isRegExp";
 import type { Scope } from "babel-traverse";
 import * as t from "./index";
 
-export function toComputedKey(node: Object, key: Object = node.key || node.property): Object {
+export function toComputedKey(
+  node: Object,
+  key: Object = node.key || node.property,
+): Object {
   if (!node.computed) {
     if (t.isIdentifier(key)) key = t.stringLiteral(key.name);
   }
   return key;
 }
 
-
-function gatherSequenceExpressions(nodes: Array<Object>, scope: Scope, declars: Array<Object>): ?Object {
+function gatherSequenceExpressions(
+  nodes: Array<Object>,
+  scope: Scope,
+  declars: Array<Object>,
+): ?Object {
   const exprs = [];
   let ensureLastUndefined = true;
 
@@ -41,12 +47,12 @@ function gatherSequenceExpressions(nodes: Array<Object>, scope: Scope, declars:
 
       ensureLastUndefined = true;
     } else if (t.isIfStatement(node)) {
-      const consequent = node.consequent ?
-        gatherSequenceExpressions([node.consequent], scope, declars) :
-        scope.buildUndefinedNode();
-      const alternate = node.alternate ?
-        gatherSequenceExpressions([node.alternate], scope, declars) :
-        scope.buildUndefinedNode();
+      const consequent = node.consequent
+        ? gatherSequenceExpressions([node.consequent], scope, declars)
+        : scope.buildUndefinedNode();
+      const alternate = node.alternate
+        ? gatherSequenceExpressions([node.alternate], scope, declars)
+        : scope.buildUndefinedNode();
       if (!consequent || !alternate) return; // bailed
 
       exprs.push(t.conditionalExpression(node.test, consequent, alternate));
@@ -84,7 +90,10 @@ function gatherSequenceExpressions(nodes: Array<Object>, scope: Scope, declars:
  * Expression statements are just resolved to their expression.
  */
 
-export function toSequenceExpression(nodes: Array<Object>, scope: Scope): ?Object {
+export function toSequenceExpression(
+  nodes: Array<Object>,
+  scope: Scope,
+): ?Object {
   if (!nodes || !nodes.length) return;
 
   const declars = [];
@@ -124,9 +133,9 @@ export function toKeyAlias(node: Object, key: Object = node.key): string {
 
 toKeyAlias.uid = 0;
 
-toKeyAlias.increment = function () {
+toKeyAlias.increment = function() {
   if (toKeyAlias.uid >= Number.MAX_SAFE_INTEGER) {
-    return toKeyAlias.uid = 0;
+    return (toKeyAlias.uid = 0);
   } else {
     return toKeyAlias.uid++;
   }
@@ -142,7 +151,7 @@ export function toIdentifier(name: string): string {
   name = name.replace(/^[-0-9]+/, "");
 
   // camel case
-  name = name.replace(/[-\s]+(.)?/g, function (match, c) {
+  name = name.replace(/[-\s]+(.)?/g, function(match, c) {
     return c ? c.toUpperCase() : "";
   });
 
diff --git a/packages/babel-types/src/definitions/core.js b/packages/babel-types/src/definitions/core.js
index d72feba5e3..3c51f41bf2 100644
--- a/packages/babel-types/src/definitions/core.js
+++ b/packages/babel-types/src/definitions/core.js
@@ -23,7 +23,9 @@ defineType("ArrayExpression", {
     elements: {
       validate: chain(
         assertValueType("array"),
-        assertEach(assertNodeOrValueType("null", "Expression", "SpreadElement"))
+        assertEach(
+          assertNodeOrValueType("null", "Expression", "SpreadElement"),
+        ),
       ),
       default: [],
     },
@@ -89,11 +91,17 @@ defineType("BlockStatement", {
   visitor: ["directives", "body"],
   fields: {
     directives: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Directive"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Directive")),
+      ),
       default: [],
     },
     body: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Statement"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Statement")),
+      ),
     },
   },
   aliases: ["Scopable", "BlockParent", "Block", "Statement"],
@@ -117,7 +125,10 @@ defineType("CallExpression", {
       validate: assertNodeType("Expression"),
     },
     arguments: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Expression", "SpreadElement"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Expression", "SpreadElement")),
+      ),
     },
     optional: {
       validate: assertOneOf(true, false),
@@ -210,7 +221,14 @@ defineType("File", {
 
 defineType("ForInStatement", {
   visitor: ["left", "right", "body"],
-  aliases: ["Scopable", "Statement", "For", "BlockParent", "Loop", "ForXStatement"],
+  aliases: [
+    "Scopable",
+    "Statement",
+    "For",
+    "BlockParent",
+    "Loop",
+    "ForXStatement",
+  ],
   fields: {
     left: {
       validate: assertNodeType("VariableDeclaration", "LVal"),
@@ -254,7 +272,10 @@ defineType("FunctionDeclaration", {
       validate: assertNodeType("Identifier"),
     },
     params: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("LVal"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("LVal")),
+      ),
     },
     body: {
       validate: assertNodeType("BlockStatement"),
@@ -281,14 +302,24 @@ defineType("FunctionDeclaration", {
 
 defineType("FunctionExpression", {
   inherits: "FunctionDeclaration",
-  aliases: ["Scopable", "Function", "BlockParent", "FunctionParent", "Expression", "Pureish"],
+  aliases: [
+    "Scopable",
+    "Function",
+    "BlockParent",
+    "FunctionParent",
+    "Expression",
+    "Pureish",
+  ],
   fields: {
     id: {
       validate: assertNodeType("Identifier"),
       optional: true,
     },
     params: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("LVal"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("LVal")),
+      ),
     },
     body: {
       validate: assertNodeType("BlockStatement"),
@@ -317,7 +348,10 @@ defineType("Identifier", {
       },
     },
     decorators: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Decorator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Decorator")),
+      ),
     },
   },
 });
@@ -428,15 +462,15 @@ defineType("MemberExpression", {
       validate: assertNodeType("Expression"),
     },
     property: {
-      validate: (function () {
+      validate: (function() {
         const normal = assertNodeType("Identifier");
         const computed = assertNodeType("Expression");
 
-        return function (node, key, val) {
+        return function(node, key, val) {
           const validator = node.computed ? computed : normal;
           validator(node, key, val);
         };
-      }()),
+      })(),
     },
     computed: {
       default: false,
@@ -456,7 +490,10 @@ defineType("NewExpression", {
       validate: assertNodeType("Expression"),
     },
     arguments: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Expression", "SpreadElement"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Expression", "SpreadElement")),
+      ),
     },
     optional: {
       validate: assertOneOf(true, false),
@@ -470,11 +507,17 @@ defineType("Program", {
   builder: ["body", "directives"],
   fields: {
     directives: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Directive"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Directive")),
+      ),
       default: [],
     },
     body: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Statement"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Statement")),
+      ),
     },
   },
   aliases: ["Scopable", "BlockParent", "Block", "FunctionParent"],
@@ -487,7 +530,9 @@ defineType("ObjectExpression", {
     properties: {
       validate: chain(
         assertValueType("array"),
-        assertEach(assertNodeType("ObjectMethod", "ObjectProperty", "SpreadElement"))
+        assertEach(
+          assertNodeType("ObjectMethod", "ObjectProperty", "SpreadElement"),
+        ),
       ),
     },
   },
@@ -497,7 +542,10 @@ defineType("ObjectMethod", {
   builder: ["kind", "key", "params", "body", "computed"],
   fields: {
     kind: {
-      validate: chain(assertValueType("string"), assertOneOf("method", "get", "set")),
+      validate: chain(
+        assertValueType("string"),
+        assertOneOf("method", "get", "set"),
+      ),
       default: "method",
     },
     computed: {
@@ -505,18 +553,25 @@ defineType("ObjectMethod", {
       default: false,
     },
     key: {
-      validate: (function () {
+      validate: (function() {
         const normal = assertNodeType("Expression");
-        const computed = assertNodeType("Identifier", "StringLiteral", "NumericLiteral");
+        const computed = assertNodeType(
+          "Identifier",
+          "StringLiteral",
+          "NumericLiteral",
+        );
 
-        return function (node, key, val) {
+        return function(node, key, val) {
           const validator = node.computed ? computed : normal;
           validator(node, key, val);
         };
-      }()),
+      })(),
     },
     decorators: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Decorator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Decorator")),
+      ),
     },
     body: {
       validate: assertNodeType("BlockStatement"),
@@ -530,8 +585,23 @@ defineType("ObjectMethod", {
       validate: assertValueType("boolean"),
     },
   },
-  visitor: ["key", "params", "body", "decorators", "returnType", "typeParameters"],
-  aliases: ["UserWhitespacable", "Function", "Scopable", "BlockParent", "FunctionParent", "Method", "ObjectMember"],
+  visitor: [
+    "key",
+    "params",
+    "body",
+    "decorators",
+    "returnType",
+    "typeParameters",
+  ],
+  aliases: [
+    "UserWhitespacable",
+    "Function",
+    "Scopable",
+    "BlockParent",
+    "FunctionParent",
+    "Method",
+    "ObjectMember",
+  ],
 });
 
 defineType("ObjectProperty", {
@@ -542,15 +612,19 @@ defineType("ObjectProperty", {
       default: false,
     },
     key: {
-      validate: (function () {
-        const normal = assertNodeType("Identifier", "StringLiteral", "NumericLiteral");
+      validate: (function() {
+        const normal = assertNodeType(
+          "Identifier",
+          "StringLiteral",
+          "NumericLiteral",
+        );
         const computed = assertNodeType("Expression");
 
-        return function (node, key, val) {
+        return function(node, key, val) {
           const validator = node.computed ? computed : normal;
           validator(node, key, val);
         };
-      }()),
+      })(),
     },
     value: {
       validate: assertNodeType("Expression", "Pattern", "RestElement"),
@@ -560,7 +634,10 @@ defineType("ObjectProperty", {
       default: false,
     },
     decorators: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Decorator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Decorator")),
+      ),
       optional: true,
     },
   },
@@ -576,7 +653,10 @@ defineType("RestElement", {
       validate: assertNodeType("LVal"),
     },
     decorators: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Decorator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Decorator")),
+      ),
     },
   },
 });
@@ -596,7 +676,10 @@ defineType("SequenceExpression", {
   visitor: ["expressions"],
   fields: {
     expressions: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Expression"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Expression")),
+      ),
     },
   },
   aliases: ["Expression"],
@@ -610,7 +693,10 @@ defineType("SwitchCase", {
       optional: true,
     },
     consequent: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Statement"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Statement")),
+      ),
     },
   },
 });
@@ -623,7 +709,10 @@ defineType("SwitchStatement", {
       validate: assertNodeType("Expression"),
     },
     cases: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("SwitchCase"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("SwitchCase")),
+      ),
     },
   },
 });
@@ -701,10 +790,16 @@ defineType("VariableDeclaration", {
   aliases: ["Statement", "Declaration"],
   fields: {
     kind: {
-      validate: chain(assertValueType("string"), assertOneOf("var", "let", "const")),
+      validate: chain(
+        assertValueType("string"),
+        assertOneOf("var", "let", "const"),
+      ),
     },
     declarations: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("VariableDeclarator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("VariableDeclarator")),
+      ),
     },
   },
 });
diff --git a/packages/babel-types/src/definitions/es2015.js b/packages/babel-types/src/definitions/es2015.js
index d5f7d7f91b..4df89a0dd1 100644
--- a/packages/babel-types/src/definitions/es2015.js
+++ b/packages/babel-types/src/definitions/es2015.js
@@ -19,7 +19,10 @@ defineType("AssignmentPattern", {
       validate: assertNodeType("Expression"),
     },
     decorators: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Decorator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Decorator")),
+      ),
     },
   },
 });
@@ -29,10 +32,16 @@ defineType("ArrayPattern", {
   aliases: ["Pattern", "LVal"],
   fields: {
     elements: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Identifier", "Pattern", "RestElement"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Identifier", "Pattern", "RestElement")),
+      ),
     },
     decorators: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Decorator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Decorator")),
+      ),
     },
   },
 });
@@ -40,10 +49,20 @@ defineType("ArrayPattern", {
 defineType("ArrowFunctionExpression", {
   builder: ["params", "body", "async"],
   visitor: ["params", "body", "returnType", "typeParameters"],
-  aliases: ["Scopable", "Function", "BlockParent", "FunctionParent", "Expression", "Pureish"],
+  aliases: [
+    "Scopable",
+    "Function",
+    "BlockParent",
+    "FunctionParent",
+    "Expression",
+    "Pureish",
+  ],
   fields: {
     params: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("LVal"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("LVal")),
+      ),
     },
     body: {
       validate: assertNodeType("BlockStatement", "Expression"),
@@ -59,7 +78,10 @@ defineType("ClassBody", {
   visitor: ["body"],
   fields: {
     body: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("ClassMethod", "ClassProperty"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("ClassMethod", "ClassProperty")),
+      ),
     },
   },
 });
@@ -89,7 +111,10 @@ defineType("ClassDeclaration", {
       validate: assertNodeType("Expression"),
     },
     decorators: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Decorator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Decorator")),
+      ),
     },
   },
 });
@@ -110,14 +135,22 @@ defineType("ClassExpression", {
       validate: assertNodeType("Expression"),
     },
     decorators: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Decorator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Decorator")),
+      ),
     },
   },
 });
 
 defineType("ExportAllDeclaration", {
   visitor: ["source"],
-  aliases: ["Statement", "Declaration", "ModuleDeclaration", "ExportDeclaration"],
+  aliases: [
+    "Statement",
+    "Declaration",
+    "ModuleDeclaration",
+    "ExportDeclaration",
+  ],
   fields: {
     source: {
       validate: assertNodeType("StringLiteral"),
@@ -127,24 +160,41 @@ defineType("ExportAllDeclaration", {
 
 defineType("ExportDefaultDeclaration", {
   visitor: ["declaration"],
-  aliases: ["Statement", "Declaration", "ModuleDeclaration", "ExportDeclaration"],
+  aliases: [
+    "Statement",
+    "Declaration",
+    "ModuleDeclaration",
+    "ExportDeclaration",
+  ],
   fields: {
     declaration: {
-      validate: assertNodeType("FunctionDeclaration", "ClassDeclaration", "Expression"),
+      validate: assertNodeType(
+        "FunctionDeclaration",
+        "ClassDeclaration",
+        "Expression",
+      ),
     },
   },
 });
 
 defineType("ExportNamedDeclaration", {
   visitor: ["declaration", "specifiers", "source"],
-  aliases: ["Statement", "Declaration", "ModuleDeclaration", "ExportDeclaration"],
+  aliases: [
+    "Statement",
+    "Declaration",
+    "ModuleDeclaration",
+    "ExportDeclaration",
+  ],
   fields: {
     declaration: {
       validate: assertNodeType("Declaration"),
       optional: true,
     },
     specifiers: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("ExportSpecifier"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("ExportSpecifier")),
+      ),
     },
     source: {
       validate: assertNodeType("StringLiteral"),
@@ -168,7 +218,14 @@ defineType("ExportSpecifier", {
 
 defineType("ForOfStatement", {
   visitor: ["left", "right", "body"],
-  aliases: ["Scopable", "Statement", "For", "BlockParent", "Loop", "ForXStatement"],
+  aliases: [
+    "Scopable",
+    "Statement",
+    "For",
+    "BlockParent",
+    "Loop",
+    "ForXStatement",
+  ],
   fields: {
     left: {
       validate: assertNodeType("VariableDeclaration", "LVal"),
@@ -193,7 +250,13 @@ defineType("ImportDeclaration", {
     specifiers: {
       validate: chain(
         assertValueType("array"),
-        assertEach(assertNodeType("ImportSpecifier", "ImportDefaultSpecifier", "ImportNamespaceSpecifier"))
+        assertEach(
+          assertNodeType(
+            "ImportSpecifier",
+            "ImportDefaultSpecifier",
+            "ImportNamespaceSpecifier",
+          ),
+        ),
       ),
     },
     source: {
@@ -256,10 +319,20 @@ defineType("MetaProperty", {
 defineType("ClassMethod", {
   aliases: ["Function", "Scopable", "BlockParent", "FunctionParent", "Method"],
   builder: ["kind", "key", "params", "body", "computed", "static"],
-  visitor: ["key", "params", "body", "decorators", "returnType", "typeParameters"],
+  visitor: [
+    "key",
+    "params",
+    "body",
+    "decorators",
+    "returnType",
+    "typeParameters",
+  ],
   fields: {
     kind: {
-      validate: chain(assertValueType("string"), assertOneOf("get", "set", "method", "constructor")),
+      validate: chain(
+        assertValueType("string"),
+        assertOneOf("get", "set", "method", "constructor"),
+      ),
       default: "method",
     },
     computed: {
@@ -271,18 +344,25 @@ defineType("ClassMethod", {
       validate: assertValueType("boolean"),
     },
     key: {
-      validate: (function () {
+      validate: (function() {
         const normal = assertNodeType("Expression");
-        const computed = assertNodeType("Identifier", "StringLiteral", "NumericLiteral");
+        const computed = assertNodeType(
+          "Identifier",
+          "StringLiteral",
+          "NumericLiteral",
+        );
 
-        return function (node, key, val) {
+        return function(node, key, val) {
           const validator = node.computed ? computed : normal;
           validator(node, key, val);
         };
-      }()),
+      })(),
     },
     params: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("LVal"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("LVal")),
+      ),
     },
     body: {
       validate: assertNodeType("BlockStatement"),
@@ -303,10 +383,16 @@ defineType("ObjectPattern", {
   aliases: ["Pattern", "LVal"],
   fields: {
     properties: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("RestElement", "Property"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("RestElement", "Property")),
+      ),
     },
     decorators: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Decorator"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Decorator")),
+      ),
     },
   },
 });
@@ -356,10 +442,16 @@ defineType("TemplateLiteral", {
   aliases: ["Expression", "Literal"],
   fields: {
     quasis: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("TemplateElement"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("TemplateElement")),
+      ),
     },
     expressions: {
-      validate: chain(assertValueType("array"), assertEach(assertNodeType("Expression"))),
+      validate: chain(
+        assertValueType("array"),
+        assertEach(assertNodeType("Expression")),
+      ),
     },
   },
 });
diff --git a/packages/babel-types/src/definitions/flow.js b/packages/babel-types/src/definitions/flow.js
index 2bb5d372b2..81640c6ec6 100644
--- a/packages/babel-types/src/definitions/flow.js
+++ b/packages/babel-types/src/definitions/flow.js
@@ -1,6 +1,4 @@
-import defineType, {
-  assertValueType,
-} from "./index";
+import defineType, { assertValueType } from "./index";
 
 defineType("AnyTypeAnnotation", {
   aliases: ["Flow", "FlowBaseAnnotation"],
diff --git a/packages/babel-types/src/definitions/index.js b/packages/babel-types/src/definitions/index.js
index 750a81193f..566d7223db 100644
--- a/packages/babel-types/src/definitions/index.js
+++ b/packages/babel-types/src/definitions/index.js
@@ -34,7 +34,9 @@ export function assertOneOf(...vals): Function {
   function validate(node, key, val) {
     if (vals.indexOf(val) < 0) {
       throw new TypeError(
-        `Property ${key} expected value to be one of ${JSON.stringify(vals)} but got ${JSON.stringify(val)}`
+        `Property ${key} expected value to be one of ${JSON.stringify(
+          vals,
+        )} but got ${JSON.stringify(val)}`,
       );
     }
   }
@@ -57,8 +59,9 @@ export function assertNodeType(...types: Array<string>): Function {
 
     if (!valid) {
       throw new TypeError(
-        `Property ${key} of ${node.type} expected node to be of a type ${JSON.stringify(types)} ` +
-        `but instead got ${JSON.stringify(val && val.type)}`
+        `Property ${key} of ${node.type} expected node to be of a type ${JSON.stringify(
+          types,
+        )} ` + `but instead got ${JSON.stringify(val && val.type)}`,
       );
     }
   }
@@ -81,8 +84,9 @@ export function assertNodeOrValueType(...types: Array<string>): Function {
 
     if (!valid) {
       throw new TypeError(
-        `Property ${key} of ${node.type} expected node to be of a type ${JSON.stringify(types)} ` +
-        `but instead got ${JSON.stringify(val && val.type)}`
+        `Property ${key} of ${node.type} expected node to be of a type ${JSON.stringify(
+          types,
+        )} ` + `but instead got ${JSON.stringify(val && val.type)}`,
       );
     }
   }
@@ -97,7 +101,9 @@ export function assertValueType(type: string): Function {
     const valid = getType(val) === type;
 
     if (!valid) {
-      throw new TypeError(`Property ${key} expected type of ${type} but got ${getType(val)}`);
+      throw new TypeError(
+        `Property ${key} expected type of ${type} but got ${getType(val)}`,
+      );
     }
   }
 
@@ -119,12 +125,12 @@ export function chain(...fns: Array<Function>): Function {
 export default function defineType(
   type: string,
   opts: {
-    fields?: Object;
-    visitor?: Array<string>;
-    aliases?: Array<string>;
-    builder?: Array<string>;
-    inherits?: string;
-    deprecatedAlias?: string;
+    fields?: Object,
+    visitor?: Array<string>,
+    aliases?: Array<string>,
+    builder?: Array<string>,
+    inherits?: string,
+    deprecatedAlias?: string,
   } = {},
 ) {
   const inherits = (opts.inherits && store[opts.inherits]) || {};
diff --git a/packages/babel-types/src/definitions/jsx.js b/packages/babel-types/src/definitions/jsx.js
index 28a8921c23..01ed6c7c5f 100644
--- a/packages/babel-types/src/definitions/jsx.js
+++ b/packages/babel-types/src/definitions/jsx.js
@@ -1,4 +1,9 @@
-import defineType, { assertNodeType, assertValueType, chain, assertEach } from "./index";
+import defineType, {
+  assertNodeType,
+  assertValueType,
+  chain,
+  assertEach,
+} from "./index";
 
 defineType("JSXAttribute", {
   visitor: ["name", "value"],
@@ -9,7 +14,11 @@ defineType("JSXAttribute", {
     },
     value: {
       optional: true,
-      validate: assertNodeType("JSXElement", "StringLiteral", "JSXExpressionContainer"),
+      validate: assertNodeType(
+        "JSXElement",
+        "StringLiteral",
+        "JSXExpressionContainer",
+      ),
     },
   },
 });
@@ -39,7 +48,14 @@ defineType("JSXElement", {
     children: {
       validate: chain(
         assertValueType("array"),
-        assertEach(assertNodeType("JSXText", "JSXExpressionContainer", "JSXSpreadChild", "JSXElement"))
+        assertEach(
+          assertNodeType(
+            "JSXText",
+            "JSXExpressionContainer",
+            "JSXSpreadChild",
+            "JSXElement",
+          ),
+        ),
       ),
     },
   },
@@ -120,7 +136,7 @@ defineType("JSXOpeningElement", {
     attributes: {
       validate: chain(
         assertValueType("array"),
-        assertEach(assertNodeType("JSXAttribute", "JSXSpreadAttribute"))
+        assertEach(assertNodeType("JSXAttribute", "JSXSpreadAttribute")),
       ),
     },
   },
diff --git a/packages/babel-types/src/flow.js b/packages/babel-types/src/flow.js
index 6deb48c23d..a1d0063e70 100644
--- a/packages/babel-types/src/flow.js
+++ b/packages/babel-types/src/flow.js
@@ -66,7 +66,7 @@ export function removeTypeDuplicates(nodes: Array<Object>): Array<Object> {
         if (existing.typeParameters) {
           if (node.typeParameters) {
             existing.typeParameters.params = removeTypeDuplicates(
-              existing.typeParameters.params.concat(node.typeParameters.params)
+              existing.typeParameters.params.concat(node.typeParameters.params),
             );
           }
         } else {
diff --git a/packages/babel-types/src/index.js b/packages/babel-types/src/index.js
index a07cdf48c5..9b138da49e 100644
--- a/packages/babel-types/src/index.js
+++ b/packages/babel-types/src/index.js
@@ -12,15 +12,19 @@ const t = exports;
 function registerType(type: string) {
   let is = t[`is${type}`];
   if (!is) {
-    is = t[`is${type}`] = function (node, opts) {
+    is = t[`is${type}`] = function(node, opts) {
       return t.is(type, node, opts);
     };
   }
 
-  t[`assert${type}`] = function (node, opts) {
+  t[`assert${type}`] = function(node, opts) {
     opts = opts || {};
     if (!is(node, opts)) {
-      throw new Error(`Expected type ${JSON.stringify(type)} with option ${JSON.stringify(opts)}`);
+      throw new Error(
+        `Expected type ${JSON.stringify(type)} with option ${JSON.stringify(
+          opts,
+        )}`,
+      );
     }
   };
 }
@@ -50,7 +54,13 @@ export {
 } from "./constants";
 
 import "./definitions/init";
-import { VISITOR_KEYS, ALIAS_KEYS, NODE_FIELDS, BUILDER_KEYS, DEPRECATED_KEYS } from "./definitions";
+import {
+  VISITOR_KEYS,
+  ALIAS_KEYS,
+  NODE_FIELDS,
+  BUILDER_KEYS,
+  DEPRECATED_KEYS,
+} from "./definitions";
 export { VISITOR_KEYS, ALIAS_KEYS, NODE_FIELDS, BUILDER_KEYS, DEPRECATED_KEYS };
 
 import * as _react from "./react";
@@ -78,9 +88,10 @@ export function isSpreadProperty(...args) {
 
 t.FLIPPED_ALIAS_KEYS = {};
 
-Object.keys(t.ALIAS_KEYS).forEach(function (type) {
-  t.ALIAS_KEYS[type].forEach(function (alias) {
-    const types = t.FLIPPED_ALIAS_KEYS[alias] = t.FLIPPED_ALIAS_KEYS[alias] || [];
+Object.keys(t.ALIAS_KEYS).forEach(function(type) {
+  t.ALIAS_KEYS[type].forEach(function(alias) {
+    const types = (t.FLIPPED_ALIAS_KEYS[alias] =
+      t.FLIPPED_ALIAS_KEYS[alias] || []);
     types.push(type);
   });
 });
@@ -89,7 +100,7 @@ Object.keys(t.ALIAS_KEYS).forEach(function (type) {
  * Registers `is[Alias]` and `assert[Alias]` functions for all aliases.
  */
 
-Object.keys(t.FLIPPED_ALIAS_KEYS).forEach(function (type) {
+Object.keys(t.FLIPPED_ALIAS_KEYS).forEach(function(type) {
   t[type.toUpperCase() + "_TYPES"] = t.FLIPPED_ALIAS_KEYS[type];
   registerType(type);
 });
@@ -145,14 +156,14 @@ export function isType(nodeType: string, targetType: string): boolean {
  * Description
  */
 
-Object.keys(t.BUILDER_KEYS).forEach(function (type) {
+Object.keys(t.BUILDER_KEYS).forEach(function(type) {
   const keys = t.BUILDER_KEYS[type];
 
   function builder() {
     if (arguments.length > keys.length) {
       throw new Error(
         `t.${type}: Too many arguments passed. Received ${arguments.length} but can receive ` +
-        `no more than ${keys.length}`
+          `no more than ${keys.length}`,
       );
     }
 
@@ -189,7 +200,7 @@ for (const type in t.DEPRECATED_KEYS) {
   const newType = t.DEPRECATED_KEYS[type];
 
   function proxy(fn) {
-    return function () {
+    return function() {
       console.trace(`The node type ${type} has been renamed to ${newType}`);
       return fn.apply(this, arguments);
     };
@@ -237,8 +248,16 @@ export function shallowEqual(actual: Object, expected: Object): boolean {
  * Append a node to a member expression.
  */
 
-export function appendToMemberExpression(member: Object, append: Object, computed?: boolean): Object {
-  member.object = t.memberExpression(member.object, member.property, member.computed);
+export function appendToMemberExpression(
+  member: Object,
+  append: Object,
+  computed?: boolean,
+): Object {
+  member.object = t.memberExpression(
+    member.object,
+    member.property,
+    member.computed,
+  );
   member.property = append;
   member.computed = !!computed;
   return member;
@@ -248,7 +267,10 @@ export function appendToMemberExpression(member: Object, append: Object, compute
  * Prepend a node to a member expression.
  */
 
-export function prependToMemberExpression(member: Object, prepend: Object): Object {
+export function prependToMemberExpression(
+  member: Object,
+  prepend: Object,
+): Object {
   member.object = t.memberExpression(prepend, member.object);
   return member;
 }
@@ -259,7 +281,7 @@ export function prependToMemberExpression(member: Object, prepend: Object): Obje
  */
 
 export function ensureBlock(node: Object, key: string = "body"): Object {
-  return node[key] = t.toBlock(node[key], node);
+  return (node[key] = t.toBlock(node[key], node));
 }
 
 /**
@@ -325,7 +347,7 @@ export function cloneDeep(node: Object): Object {
 export function matchesPattern(
   member: Object,
   match: string | Array<string>,
-  allowPartial?: boolean
+  allowPartial?: boolean,
 ): boolean {
   // not a member expression
   if (!t.isMemberExpression(member)) return false;
@@ -367,9 +389,12 @@ export function matchesPattern(
  * parsed nodes of `React.createClass` and `React["createClass"]`.
  */
 
-export function buildMatchMemberExpression(match: string, allowPartial?: boolean): (Object) => boolean {
+export function buildMatchMemberExpression(
+  match: string,
+  allowPartial?: boolean,
+): Object => boolean {
   const parts = match.split(".");
-  return function (member) {
+  return function(member) {
     return matchesPattern(member, parts, allowPartial);
   };
 }
@@ -410,10 +435,7 @@ export function inheritInnerComments(child: Object, parent: Object) {
 
 function _inheritComments(key, child, parent) {
   if (child && parent) {
-    child[key] = uniq(
-      [].concat(child[key], parent[key])
-        .filter(Boolean)
-    );
+    child[key] = uniq([].concat(child[key], parent[key]).filter(Boolean));
   }
 }
 
@@ -473,7 +495,11 @@ toFastProperties(t.VISITOR_KEYS);
  * A prefix AST traversal implementation implementation.
  */
 
-export function traverseFast(node: Node, enter: (node: Node) => void, opts?: Object) {
+export function traverseFast(
+  node: Node,
+  enter: (node: Node) => void,
+  opts?: Object,
+) {
   if (!node) return;
 
   const keys = t.VISITOR_KEYS[node.type];
@@ -495,15 +521,11 @@ export function traverseFast(node: Node, enter: (node: Node) => void, opts?: Obj
   }
 }
 
-const CLEAR_KEYS: Array = [
-  "tokens",
-  "start", "end", "loc",
-  "raw", "rawValue",
-];
+const CLEAR_KEYS: Array = ["tokens", "start", "end", "loc", "raw", "rawValue"];
 
-const CLEAR_KEYS_PLUS_COMMENTS: Array = t.COMMENT_KEYS.concat([
-  "comments",
-]).concat(CLEAR_KEYS);
+const CLEAR_KEYS_PLUS_COMMENTS: Array = t.COMMENT_KEYS
+  .concat(["comments"])
+  .concat(CLEAR_KEYS);
 
 /**
  * Remove all of the _* properties from a node along with the additional metadata
diff --git a/packages/babel-types/src/retrievers.js b/packages/babel-types/src/retrievers.js
index 734e4dfc7e..e8469fafa4 100644
--- a/packages/babel-types/src/retrievers.js
+++ b/packages/babel-types/src/retrievers.js
@@ -7,7 +7,7 @@ import * as t from "./index";
 export function getBindingIdentifiers(
   node: Object,
   duplicates?: boolean,
-  outerOnly?: boolean
+  outerOnly?: boolean,
 ): Object {
   let search = [].concat(node);
   const ids = Object.create(null);
@@ -20,7 +20,7 @@ export function getBindingIdentifiers(
 
     if (t.isIdentifier(id)) {
       if (duplicates) {
-        const _ids = ids[id.name] = ids[id.name] || [];
+        const _ids = (ids[id.name] = ids[id.name] || []);
         _ids.push(id);
       } else {
         ids[id.name] = id;
diff --git a/packages/babel-types/src/validators.js b/packages/babel-types/src/validators.js
index 39cffec8a1..14741ad4b7 100644
--- a/packages/babel-types/src/validators.js
+++ b/packages/babel-types/src/validators.js
@@ -165,7 +165,10 @@ export function isReferenced(node: Object, parent: Object): boolean {
  */
 
 export function isValidIdentifier(name: string): boolean {
-  if (typeof name !== "string" || esutils.keyword.isReservedWordES6(name, true)) {
+  if (
+    typeof name !== "string" ||
+    esutils.keyword.isReservedWordES6(name, true)
+  ) {
     return false;
   } else if (name === "await") {
     // invalid in module, valid in script; better be safe (see #4952)
@@ -180,7 +183,10 @@ export function isValidIdentifier(name: string): boolean {
  */
 
 export function isLet(node: Object): boolean {
-  return t.isVariableDeclaration(node) && (node.kind !== "var" || node[BLOCK_SCOPED_SYMBOL]);
+  return (
+    t.isVariableDeclaration(node) &&
+    (node.kind !== "var" || node[BLOCK_SCOPED_SYMBOL])
+  );
 }
 
 /**
@@ -188,7 +194,9 @@ export function isLet(node: Object): boolean {
  */
 
 export function isBlockScoped(node: Object): boolean {
-  return t.isFunctionDeclaration(node) || t.isClassDeclaration(node) || t.isLet(node);
+  return (
+    t.isFunctionDeclaration(node) || t.isClassDeclaration(node) || t.isLet(node)
+  );
 }
 
 /**
@@ -196,7 +204,9 @@ export function isBlockScoped(node: Object): boolean {
  */
 
 export function isVar(node: Object): boolean {
-  return t.isVariableDeclaration(node, { kind: "var" }) && !node[BLOCK_SCOPED_SYMBOL];
+  return (
+    t.isVariableDeclaration(node, { kind: "var" }) && !node[BLOCK_SCOPED_SYMBOL]
+  );
 }
 
 /**
@@ -204,8 +214,12 @@ export function isVar(node: Object): boolean {
  */
 
 export function isSpecifierDefault(specifier: Object): boolean {
-  return t.isImportDefaultSpecifier(specifier) ||
-         t.isIdentifier(specifier.imported || specifier.exported, { name: "default" });
+  return (
+    t.isImportDefaultSpecifier(specifier) ||
+    t.isIdentifier(specifier.imported || specifier.exported, {
+      name: "default",
+    })
+  );
 }
 
 /**
@@ -245,7 +259,12 @@ export function isImmutable(node: Object): boolean {
  */
 
 export function isNodesEquivalent(a, b) {
-  if (typeof a !== "object" || typeof b !== "object" || a == null || b == null) {
+  if (
+    typeof a !== "object" ||
+    typeof b !== "object" ||
+    a == null ||
+    b == null
+  ) {
     return a === b;
   }
 
diff --git a/packages/babel-types/test/cloning.js b/packages/babel-types/test/cloning.js
index 9e3b41f475..8303cff327 100644
--- a/packages/babel-types/test/cloning.js
+++ b/packages/babel-types/test/cloning.js
@@ -2,21 +2,21 @@ import * as t from "../lib";
 import assert from "assert";
 import { parse } from "babylon";
 
-suite("cloning", function () {
-  suite("clone", function () {
-    it("should handle undefined", function () {
+suite("cloning", function() {
+  suite("clone", function() {
+    it("should handle undefined", function() {
       const node = undefined;
       const cloned = t.clone(node);
       assert(cloned === undefined);
     });
 
-    it("should handle null", function () {
+    it("should handle null", function() {
       const node = null;
       const cloned = t.clone(node);
       assert(cloned === null);
     });
 
-    it("should handle simple cases", function () {
+    it("should handle simple cases", function() {
       const node = t.arrayExpression([null, t.identifier("a")]);
       const cloned = t.clone(node);
       assert(node !== cloned);
@@ -24,34 +24,34 @@ suite("cloning", function () {
     });
   });
 
-  suite("cloneDeep", function () {
-    it("should handle undefined", function () {
+  suite("cloneDeep", function() {
+    it("should handle undefined", function() {
       const node = undefined;
       const cloned = t.cloneDeep(node);
       assert(cloned === undefined);
     });
 
-    it("should handle null", function () {
+    it("should handle null", function() {
       const node = null;
       const cloned = t.cloneDeep(node);
       assert(cloned === null);
     });
 
-    it("should handle simple cases", function () {
+    it("should handle simple cases", function() {
       const node = t.arrayExpression([null, t.identifier("a")]);
       const cloned = t.cloneDeep(node);
       assert(node !== cloned);
       assert(t.isNodesEquivalent(node, cloned) === true);
     });
 
-    it("should handle full programs", function () {
+    it("should handle full programs", function() {
       const node = parse("1 + 1");
       const cloned = t.cloneDeep(node);
       assert(node !== cloned);
       assert(t.isNodesEquivalent(node, cloned) === true);
     });
 
-    it("should handle complex programs", function () {
+    it("should handle complex programs", function() {
       const program = "'use strict'; function lol() { wow();return 1; }";
       const node = parse(program);
       const cloned = t.cloneDeep(node);
@@ -59,7 +59,7 @@ suite("cloning", function () {
       assert(t.isNodesEquivalent(node, cloned) === true);
     });
 
-    it("should handle missing array element", function () {
+    it("should handle missing array element", function() {
       const node = parse("[,0]");
       const cloned = t.cloneDeep(node);
       assert(node !== cloned);
diff --git a/packages/babel-types/test/converters.js b/packages/babel-types/test/converters.js
index 31584eb6e4..38221205bd 100644
--- a/packages/babel-types/test/converters.js
+++ b/packages/babel-types/test/converters.js
@@ -12,79 +12,103 @@ function generateCode(node) {
   return generate(node).code;
 }
 
-describe("converters", function () {
-  it("toIdentifier", function () {
+describe("converters", function() {
+  it("toIdentifier", function() {
     assert.equal(t.toIdentifier("swag-lord"), "swagLord");
   });
 
-  describe("valueToNode", function () {
-    it("number", function () {
+  describe("valueToNode", function() {
+    it("number", function() {
       assert.deepEqual(t.valueToNode(Math.PI), t.numericLiteral(Math.PI));
       assert.deepEqual(t.valueToNode(-Infinity), t.numericLiteral(-Infinity));
       assert.deepEqual(t.valueToNode(NaN), t.numericLiteral(NaN));
     });
-    it("string", function () {
-      assert.deepEqual(t.valueToNode("This is a \"string\""), t.stringLiteral("This is a \"string\""));
+    it("string", function() {
+      assert.deepEqual(
+        t.valueToNode('This is a "string"'),
+        t.stringLiteral('This is a "string"'),
+      );
     });
-    it("boolean", function () {
+    it("boolean", function() {
       assert.deepEqual(t.valueToNode(true), t.booleanLiteral(true));
       assert.deepEqual(t.valueToNode(false), t.booleanLiteral(false));
     });
-    it("null", function () {
+    it("null", function() {
       assert.deepEqual(t.valueToNode(null), t.nullLiteral());
     });
-    it("undefined", function () {
+    it("undefined", function() {
       assert.deepEqual(t.valueToNode(undefined), t.identifier("undefined"));
     });
-    it("RegExp", function () {
-      assert.deepEqual(t.valueToNode(/abc.+/gm), t.regExpLiteral("abc.+", "gm"));
+    it("RegExp", function() {
+      assert.deepEqual(
+        t.valueToNode(/abc.+/gm),
+        t.regExpLiteral("abc.+", "gm"),
+      );
     });
-    it("array", function () {
-      assert.deepEqual(t.valueToNode([1, "a"]),
-        t.arrayExpression([t.numericLiteral(1), t.stringLiteral("a")]));
+    it("array", function() {
+      assert.deepEqual(
+        t.valueToNode([1, "a"]),
+        t.arrayExpression([t.numericLiteral(1), t.stringLiteral("a")]),
+      );
     });
-    it("object", function () {
-      assert.deepEqual(t.valueToNode({
-        a: 1,
-        "b c": 2,
-      }), t.objectExpression([
-        t.objectProperty(t.identifier("a"), t.numericLiteral(1)),
-        t.objectProperty(t.stringLiteral("b c"), t.numericLiteral(2)),
-      ]));
+    it("object", function() {
+      assert.deepEqual(
+        t.valueToNode({
+          a: 1,
+          "b c": 2,
+        }),
+        t.objectExpression([
+          t.objectProperty(t.identifier("a"), t.numericLiteral(1)),
+          t.objectProperty(t.stringLiteral("b c"), t.numericLiteral(2)),
+        ]),
+      );
     });
-    it("throws if cannot convert", function () {
-      assert.throws(function () {
+    it("throws if cannot convert", function() {
+      assert.throws(function() {
         t.valueToNode(Object);
       });
-      assert.throws(function () {
+      assert.throws(function() {
         t.valueToNode(Symbol());
       });
     });
   });
-  describe("toKeyAlias", function () {
-    beforeEach(function () {
+  describe("toKeyAlias", function() {
+    beforeEach(function() {
       // make tests deterministic
       t.toKeyAlias.uid = 0;
     });
-    it("doesn't change string literals", function () {
-      assert.equal(t.toKeyAlias(t.objectProperty(t.stringLiteral("a"), t.nullLiteral())), "\"a\"");
+    it("doesn't change string literals", function() {
+      assert.equal(
+        t.toKeyAlias(t.objectProperty(t.stringLiteral("a"), t.nullLiteral())),
+        '"a"',
+      );
     });
-    it("wraps around at Number.MAX_SAFE_INTEGER", function () {
-      assert.equal(t.toKeyAlias(t.objectMethod("method", t.identifier("a"), [], t.blockStatement([]))), "0");
+    it("wraps around at Number.MAX_SAFE_INTEGER", function() {
+      assert.equal(
+        t.toKeyAlias(
+          t.objectMethod("method", t.identifier("a"), [], t.blockStatement([])),
+        ),
+        "0",
+      );
     });
   });
-  describe("toStatement", function () {
-    it("noop on statements", function () {
+  describe("toStatement", function() {
+    it("noop on statements", function() {
       const node = t.emptyStatement();
       assert.equal(t.toStatement(node), node);
       t.assertEmptyStatement(node);
     });
-    it("mutate class expression to declaration", function () {
-      const node = t.classExpression(t.identifier("A"), null, t.classBody([]), []);
+    it("mutate class expression to declaration", function() {
+      const node = t.classExpression(
+        t.identifier("A"),
+        null,
+        t.classBody([]),
+        [],
+      );
       t.toStatement(node);
       t.assertClassDeclaration(node);
     });
-    it("fail if class expression has no id", function () {
+    it("fail if class expression has no id", function() {
       const node = t.classExpression(null, null, t.classBody([]), []);
       assert.throws(function() {
         t.toStatement(node);
@@ -92,12 +116,16 @@ describe("converters", function () {
       assert.strictEqual(t.toStatement(node, /* ignore = */ true), false);
       t.assertClassExpression(node);
     });
-    it("mutate function expression to declaration", function () {
-      const node = t.functionExpression(t.identifier("A"), [], t.blockStatement([]));
+    it("mutate function expression to declaration", function() {
+      const node = t.functionExpression(
+        t.identifier("A"),
+        [],
+        t.blockStatement([]),
+      );
       t.toStatement(node);
       t.assertFunctionDeclaration(node);
     });
-    it("fail if function expression has no id", function () {
+    it("fail if function expression has no id", function() {
       const node = t.functionExpression(null, [], t.blockStatement([]));
       assert.throws(function() {
         t.toStatement(node);
@@ -105,12 +133,16 @@ describe("converters", function () {
       assert.strictEqual(t.toStatement(node, /* ignore = */ true), false);
       t.assertFunctionExpression(node);
     });
-    it("assignment expression", function () {
-      const node = t.assignmentExpression("+=", t.identifier("x"), t.numericLiteral(1));
+    it("assignment expression", function() {
+      const node = t.assignmentExpression(
+        "+=",
+        t.identifier("x"),
+        t.numericLiteral(1),
+      );
       t.assertExpressionStatement(t.toStatement(node));
       t.assertAssignmentExpression(node);
     });
-    it("fail if cannot convert node type", function () {
+    it("fail if cannot convert node type", function() {
       const node = t.yieldExpression(t.identifier("foo"));
       assert.throws(function() {
         t.toStatement(node);
@@ -119,40 +151,59 @@ describe("converters", function () {
       t.assertYieldExpression(node);
     });
   });
-  describe("toExpression", function () {
-    it("noop on expressions", function () {
+  describe("toExpression", function() {
+    it("noop on expressions", function() {
       const node = t.identifier("a");
       assert.equal(t.toExpression(node), node);
       t.assertIdentifier(node);
     });
-    it("mutate class declaration to expression", function () {
-      const node = t.classDeclaration(t.identifier("A"), null, t.classBody([]), []);
+    it("mutate class declaration to expression", function() {
+      const node = t.classDeclaration(
+        t.identifier("A"),
+        null,
+        t.classBody([]),
+        [],
+      );
       t.toExpression(node);
       t.assertClassExpression(node);
     });
-    it("mutate function declaration to expression", function () {
-      const node = t.functionDeclaration(t.identifier("A"), [], t.blockStatement([]));
+    it("mutate function declaration to expression", function() {
+      const node = t.functionDeclaration(
+        t.identifier("A"),
+        [],
+        t.blockStatement([]),
+      );
       t.toExpression(node);
       t.assertFunctionExpression(node);
     });
-    it("mutate object method to expression", function () {
-      const node = t.objectMethod("method", t.identifier("A"), [], t.blockStatement([]));
+    it("mutate object method to expression", function() {
+      const node = t.objectMethod(
+        "method",
+        t.identifier("A"),
+        [],
+        t.blockStatement([]),
+      );
       t.toExpression(node);
       t.assertFunctionExpression(node);
     });
-    it("mutate class method to expression", function () {
-      const node = t.classMethod("constructor", t.identifier("A"), [], t.blockStatement([]));
+    it("mutate class method to expression", function() {
+      const node = t.classMethod(
+        "constructor",
+        t.identifier("A"),
+        [],
+        t.blockStatement([]),
+      );
       t.toExpression(node);
       t.assertFunctionExpression(node);
     });
-    it("expression statement", function () {
+    it("expression statement", function() {
       const inner = t.yieldExpression(t.identifier("foo"));
       const node = t.expressionStatement(inner);
       t.assertYieldExpression(t.toExpression(node));
       assert.equal(t.toExpression(node), inner);
       t.assertExpressionStatement(node);
     });
-    it("fail if cannot convert node type", function () {
+    it("fail if cannot convert node type", function() {
       const node = t.program([]);
       assert.throws(function() {
         t.toExpression(node);
@@ -160,16 +211,16 @@ describe("converters", function () {
       t.assertProgram(node);
     });
   });
-  describe("toSequenceExpression", function () {
+  describe("toSequenceExpression", function() {
     let scope;
     const undefinedNode = t.identifier("undefined");
-    beforeEach(function () {
+    beforeEach(function() {
       scope = [];
-      scope.buildUndefinedNode = function () {
+      scope.buildUndefinedNode = function() {
         return undefinedNode;
       };
     });
-    it("gathers nodes into sequence", function () {
+    it("gathers nodes into sequence", function() {
       const node = t.identifier("a");
       const sequence = t.toSequenceExpression([undefinedNode, node], scope);
       t.assertSequenceExpression(sequence);
@@ -177,7 +228,7 @@ describe("converters", function () {
       assert.equal(sequence.expressions[1], node);
       t.assertIdentifier(node);
     });
-    it("avoids sequence for single node", function () {
+    it("avoids sequence for single node", function() {
       const node = t.identifier("a");
       let sequence = t.toSequenceExpression([node], scope);
       assert.equal(sequence, node);
@@ -186,17 +237,17 @@ describe("converters", function () {
       sequence = t.toSequenceExpression([block], scope);
       assert.equal(sequence, node);
     });
-    it("gathers expression", function () {
+    it("gathers expression", function() {
       const node = t.identifier("a");
       const sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.equal(sequence.expressions[1], node);
     });
-    it("gathers expression statement", function () {
+    it("gathers expression statement", function() {
       const node = t.expressionStatement(t.identifier("a"));
       const sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.equal(sequence.expressions[1], node.expression);
     });
-    it("gathers var declarations", function () {
+    it("gathers var declarations", function() {
       const node = parseCode("var a, b = 1;");
       const sequence = t.toSequenceExpression([undefinedNode, node], scope);
       t.assertIdentifier(scope[0].id, { name: "a" });
@@ -204,12 +255,12 @@ describe("converters", function () {
       assert.equal(generateCode(sequence.expressions[1]), "b = 1");
       assert.equal(generateCode(sequence.expressions[2]), "undefined");
     });
-    it("skips undefined if expression after var declaration", function () {
+    it("skips undefined if expression after var declaration", function() {
       const node = parseCode("{ var a, b = 1; true }");
       const sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.equal(generateCode(sequence.expressions[1]), "b = 1, true");
     });
-    it("bails on let and const declarations", function () {
+    it("bails on let and const declarations", function() {
       let node = parseCode("let a, b = 1;");
       let sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.isUndefined(sequence);
@@ -218,16 +269,19 @@ describe("converters", function () {
       sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.isUndefined(sequence);
     });
-    it("gathers if statements", function () {
+    it("gathers if statements", function() {
       let node = parseCode("if (true) { true }");
       let sequence = t.toSequenceExpression([undefinedNode, node], scope);
-      assert.equal(generateCode(sequence.expressions[1]), "true ? true : undefined");
+      assert.equal(
+        generateCode(sequence.expressions[1]),
+        "true ? true : undefined",
+      );
 
       node = parseCode("if (true) { true } else { b }");
       sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.equal(generateCode(sequence.expressions[1]), "true ? true : b");
     });
-    it("bails in if statements if recurse bails", function () {
+    it("bails in if statements if recurse bails", function() {
       let node = parseCode("if (true) { return }");
       let sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.isUndefined(sequence);
@@ -236,7 +290,7 @@ describe("converters", function () {
       sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.isUndefined(sequence);
     });
-    it("gathers block statements", function () {
+    it("gathers block statements", function() {
       let node = parseCode("{ a }");
       let sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.equal(generateCode(sequence.expressions[1]), "a");
@@ -245,17 +299,17 @@ describe("converters", function () {
       sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.equal(generateCode(sequence.expressions[1]), "a, b");
     });
-    it("bails in block statements if recurse bails", function () {
+    it("bails in block statements if recurse bails", function() {
       const node = parseCode("{ return }");
       const sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.isUndefined(sequence);
     });
-    it("gathers empty statements", function () {
+    it("gathers empty statements", function() {
       const node = parseCode(";");
       const sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.equal(generateCode(sequence.expressions[1]), "undefined");
     });
-    it("skips empty statement if expression afterwards", function () {
+    it("skips empty statement if expression afterwards", function() {
       const node = parseCode("{ ; true }");
       const sequence = t.toSequenceExpression([undefinedNode, node], scope);
       assert.equal(generateCode(sequence.expressions[1]), "true");
diff --git a/packages/babel-types/test/misc.js b/packages/babel-types/test/misc.js
index d49b675be4..ddba33b48e 100644
--- a/packages/babel-types/test/misc.js
+++ b/packages/babel-types/test/misc.js
@@ -8,9 +8,9 @@ function parseCode(string) {
   }).program.body[0];
 }
 
-describe("misc helpers", function () {
-  describe("matchesPattern", function () {
-    it("matches explicitly", function () {
+describe("misc helpers", function() {
+  describe("matchesPattern", function() {
+    it("matches explicitly", function() {
       const ast = parseCode("a.b.c.d").expression;
       assert(t.matchesPattern(ast, "a.b.c.d"));
       assert.isFalse(t.matchesPattern(ast, "a.b.c"));
@@ -18,7 +18,7 @@ describe("misc helpers", function () {
       assert.isFalse(t.matchesPattern(ast, "a.b.c.d.e"));
     });
 
-    it("matches partially", function () {
+    it("matches partially", function() {
       const ast = parseCode("a.b.c.d").expression;
       assert(t.matchesPattern(ast, "a.b.c.d", true));
       assert(t.matchesPattern(ast, "a.b.c", true));
@@ -26,7 +26,7 @@ describe("misc helpers", function () {
       assert.isFalse(t.matchesPattern(ast, "a.b.c.d.e", true));
     });
 
-    it("matches string literal expressions", function () {
+    it("matches string literal expressions", function() {
       const ast = parseCode("a['b'].c.d").expression;
       assert(t.matchesPattern(ast, "a.b.c.d"));
       assert.isFalse(t.matchesPattern(ast, "a.b.c"));
@@ -34,7 +34,7 @@ describe("misc helpers", function () {
       assert.isFalse(t.matchesPattern(ast, "a.b.c.d.e"));
     });
 
-    it("matches string literal expressions partially", function () {
+    it("matches string literal expressions partially", function() {
       const ast = parseCode("a['b'].c.d").expression;
       assert(t.matchesPattern(ast, "a.b.c.d", true));
       assert(t.matchesPattern(ast, "a.b.c", true));
diff --git a/packages/babel-types/test/retrievers.js b/packages/babel-types/test/retrievers.js
index 15f4149cd1..dac29c9fc5 100644
--- a/packages/babel-types/test/retrievers.js
+++ b/packages/babel-types/test/retrievers.js
@@ -6,19 +6,19 @@ function getBody(program) {
   return parse(program, { sourceType: "module" }).program.body;
 }
 
-describe("retrievers", function () {
-  describe("getBindingIdentifiers", function () {
-    it("variable declarations", function () {
+describe("retrievers", function() {
+  describe("getBindingIdentifiers", function() {
+    it("variable declarations", function() {
       const program = "var a = 1; let b = 2; const c = 3;";
       const ids = t.getBindingIdentifiers(getBody(program));
       assert.deepEqual(Object.keys(ids), ["a", "b", "c"]);
     });
-    it("function declarations", function () {
+    it("function declarations", function() {
       const program = "var foo = 1; function bar() { var baz = 2; }";
       const ids = t.getBindingIdentifiers(getBody(program));
       assert.deepEqual(Object.keys(ids), ["bar", "foo"]);
     });
-    it("export named declarations", function () {
+    it("export named declarations", function() {
       const program = "export const foo = 'foo';";
       const ids = t.getBindingIdentifiers(getBody(program));
       assert.deepEqual(Object.keys(ids), ["foo"]);
diff --git a/packages/babel-types/test/validators.js b/packages/babel-types/test/validators.js
index 8ad737b00b..8b15edb25f 100644
--- a/packages/babel-types/test/validators.js
+++ b/packages/babel-types/test/validators.js
@@ -2,9 +2,9 @@ import * as t from "../lib";
 import assert from "assert";
 import { parse } from "babylon";
 
-suite("validators", function () {
-  suite("isNodesEquivalent", function () {
-    it("should handle simple cases", function () {
+suite("validators", function() {
+  suite("isNodesEquivalent", function() {
+    it("should handle simple cases", function() {
       const mem = t.memberExpression(t.identifier("a"), t.identifier("b"));
       assert(t.isNodesEquivalent(mem, mem) === true);
 
@@ -12,12 +12,12 @@ suite("validators", function () {
       assert(t.isNodesEquivalent(mem, mem2) === false);
     });
 
-    it("should handle full programs", function () {
+    it("should handle full programs", function() {
       assert(t.isNodesEquivalent(parse("1 + 1"), parse("1+1")) === true);
       assert(t.isNodesEquivalent(parse("1 + 1"), parse("1+2")) === false);
     });
 
-    it("should handle complex programs", function () {
+    it("should handle complex programs", function() {
       const program = "'use strict'; function lol() { wow();return 1; }";
 
       assert(t.isNodesEquivalent(parse(program), parse(program)) === true);
@@ -27,28 +27,23 @@ suite("validators", function () {
       assert(t.isNodesEquivalent(parse(program), parse(program2)) === false);
     });
 
-    it("rejects 'await' as an identifier", function () {
+    it("rejects 'await' as an identifier", function() {
       assert(t.isValidIdentifier("await") === false);
     });
   });
 
-  suite("patterns", function () {
-    it("allows nested pattern structures", function () {
+  suite("patterns", function() {
+    it("allows nested pattern structures", function() {
       const pattern = t.objectPattern([
         t.objectProperty(
           t.identifier("a"),
           t.objectPattern([
-            t.objectProperty(
-              t.identifier("b"),
-              t.stringLiteral("foo")
-            ),
+            t.objectProperty(t.identifier("b"), t.stringLiteral("foo")),
             t.objectProperty(
               t.identifier("c"),
-              t.arrayPattern([
-                t.identifier("value"),
-              ])
+              t.arrayPattern([t.identifier("value")]),
             ),
-          ])
+          ]),
         ),
       ]);
 
diff --git a/scripts/generate-babel-types-docs.js b/scripts/generate-babel-types-docs.js
index 623ef62210..3f0d70e32c 100644
--- a/scripts/generate-babel-types-docs.js
+++ b/scripts/generate-babel-types-docs.js
@@ -6,7 +6,13 @@ const fs = require("fs");
 
 const types = require("../packages/babel-types");
 
-const readmePath = path.join(__dirname, "..", "packages", "babel-types", "README.md");
+const readmePath = path.join(
+  __dirname,
+  "..",
+  "packages",
+  "babel-types",
+  "README.md"
+);
 const readmeSrc = fs.readFileSync(readmePath, "utf8");
 const readme = [
   readmeSrc.split("<!-- begin generated section -->")[0].trim(),
@@ -40,7 +46,7 @@ function getType(validator) {
   } else if (validator.oneOfNodeOrValueTypes) {
     return validator.oneOfNodeOrValueTypes.join(" | ");
   } else if (validator.oneOf) {
-    return validator.oneOf.map((val) => util.inspect(val)).join(" | ");
+    return validator.oneOf.map(val => util.inspect(val)).join(" | ");
   } else if (validator.chainOf) {
     if (
       validator.chainOf.length === 2 &&
@@ -54,9 +60,11 @@ function getType(validator) {
       validator.chainOf[0].type === "string" &&
       validator.chainOf[1].oneOf
     ) {
-      return validator.chainOf[1].oneOf.map(function (val) {
-        return JSON.stringify(val);
-      }).join(" | ");
+      return validator.chainOf[1].oneOf
+        .map(function(val) {
+          return JSON.stringify(val);
+        })
+        .join(" | ");
     }
   }
   const err = new Error("Unrecognised validator type");
@@ -64,54 +72,72 @@ function getType(validator) {
   err.validator = validator;
   throw err;
 }
-Object.keys(types.BUILDER_KEYS).sort().forEach(function (key) {
+Object.keys(types.BUILDER_KEYS).sort().forEach(function(key) {
   readme.push("### " + key[0].toLowerCase() + key.substr(1));
   readme.push("```javascript");
-  readme.push("t." + key[0].toLowerCase() + key.substr(1) + "(" + types.BUILDER_KEYS[key].join(", ") + ")");
+  readme.push(
+    "t." +
+      key[0].toLowerCase() +
+      key.substr(1) +
+      "(" +
+      types.BUILDER_KEYS[key].join(", ") +
+      ")"
+  );
   readme.push("```");
   readme.push("");
-  readme.push("See also `t.is" + key + "(node, opts)` and `t.assert" + key + "(node, opts)`.");
+  readme.push(
+    "See also `t.is" +
+      key +
+      "(node, opts)` and `t.assert" +
+      key +
+      "(node, opts)`."
+  );
   readme.push("");
   if (types.ALIAS_KEYS[key] && types.ALIAS_KEYS[key].length) {
-    readme.push("Aliases: " + types.ALIAS_KEYS[key].map(function (key) {
-      return "`" + key + "`";
-    }).join(", "));
+    readme.push(
+      "Aliases: " +
+        types.ALIAS_KEYS[key]
+          .map(function(key) {
+            return "`" + key + "`";
+          })
+          .join(", ")
+    );
     readme.push("");
   }
-  Object.keys(types.NODE_FIELDS[key]).sort(function (fieldA, fieldB) {
-    const indexA = types.BUILDER_KEYS[key].indexOf(fieldA);
-    const indexB = types.BUILDER_KEYS[key].indexOf(fieldB);
-    if (indexA === indexB) return fieldA < fieldB ? -1 : 1;
-    if (indexA === -1) return 1;
-    if (indexB === -1) return -1;
-    return indexA - indexB;
-  })
-  .forEach(function (field) {
-    const defaultValue = types.NODE_FIELDS[key][field].default;
-    const fieldDescription = ["`" + field + "`"];
-    const validator = types.NODE_FIELDS[key][field].validate;
-    if (customTypes[key] && customTypes[key][field]) {
-      fieldDescription.push(customTypes[key][field]);
-    } else if (validator) {
-      try {
-        fieldDescription.push(": `" + getType(validator) + "`");
-      } catch (ex) {
-        if (ex.code === "UNEXPECTED_VALIDATOR_TYPE") {
-          console.log("Unrecognised validator type for " + key + "." + field);
-          console.dir(ex.validator, { depth: 10, colors: true });
+  Object.keys(types.NODE_FIELDS[key])
+    .sort(function(fieldA, fieldB) {
+      const indexA = types.BUILDER_KEYS[key].indexOf(fieldA);
+      const indexB = types.BUILDER_KEYS[key].indexOf(fieldB);
+      if (indexA === indexB) return fieldA < fieldB ? -1 : 1;
+      if (indexA === -1) return 1;
+      if (indexB === -1) return -1;
+      return indexA - indexB;
+    })
+    .forEach(function(field) {
+      const defaultValue = types.NODE_FIELDS[key][field].default;
+      const fieldDescription = ["`" + field + "`"];
+      const validator = types.NODE_FIELDS[key][field].validate;
+      if (customTypes[key] && customTypes[key][field]) {
+        fieldDescription.push(customTypes[key][field]);
+      } else if (validator) {
+        try {
+          fieldDescription.push(": `" + getType(validator) + "`");
+        } catch (ex) {
+          if (ex.code === "UNEXPECTED_VALIDATOR_TYPE") {
+            console.log("Unrecognised validator type for " + key + "." + field);
+            console.dir(ex.validator, { depth: 10, colors: true });
+          }
         }
       }
-    }
-    if (
-      defaultValue !== null ||
-      types.NODE_FIELDS[key][field].optional
-    ) {
-      fieldDescription.push(" (default: `" + util.inspect(defaultValue) + "`)");
-    } else {
-      fieldDescription.push(" (required)");
-    }
-    readme.push(" - " + fieldDescription.join(""));
-  });
+      if (defaultValue !== null || types.NODE_FIELDS[key][field].optional) {
+        fieldDescription.push(
+          " (default: `" + util.inspect(defaultValue) + "`)"
+        );
+      } else {
+        fieldDescription.push(" (required)");
+      }
+      readme.push(" - " + fieldDescription.join(""));
+    });
 
   readme.push("");
   readme.push("---");
diff --git a/scripts/generate-interfaces.js b/scripts/generate-interfaces.js
index 3d1d395a93..0f32a750dc 100644
--- a/scripts/generate-interfaces.js
+++ b/scripts/generate-interfaces.js
@@ -51,7 +51,7 @@ const lines = [];
 for (const type in t.NODE_FIELDS) {
   const fields = t.NODE_FIELDS[type];
 
-  const struct = ["type: \"" + type + "\";"];
+  const struct = ['type: "' + type + '";'];
   const args = [];
 
   for (const fieldName in fields) {
@@ -65,9 +65,11 @@ for (const type in t.NODE_FIELDS) {
     const validate = field.validate;
     if (validate) {
       if (validate.oneOf) {
-        typeAnnotation = validate.oneOf.map(function (val) {
-          return JSON.stringify(val);
-        }).join(" | ");
+        typeAnnotation = validate.oneOf
+          .map(function(val) {
+            return JSON.stringify(val);
+          })
+          .join(" | ");
       }
 
       if (validate.type) {
@@ -79,7 +81,9 @@ for (const type in t.NODE_FIELDS) {
       }
 
       if (validate.oneOfNodeTypes) {
-        const types = validate.oneOfNodeTypes.map((type) => `${NODE_PREFIX}${type}`);
+        const types = validate.oneOfNodeTypes.map(
+          type => `${NODE_PREFIX}${type}`
+        );
         typeAnnotation = types.join(" | ");
         if (suffix === "?") typeAnnotation = "?" + typeAnnotation;
       }
@@ -101,18 +105,24 @@ for (const type in t.NODE_FIELDS) {
   // Flow chokes on super() :/
   if (type !== "Super") {
     lines.push(
-      `declare function ${type[0].toLowerCase() + type.slice(1)}(${args.join(", ")}): ${NODE_PREFIX}${type};`
+      `declare function ${type[0].toLowerCase() + type.slice(1)}(${args.join(
+        ", "
+      )}): ${NODE_PREFIX}${type};`
     );
   }
 }
 
 for (let i = 0; i < t.TYPES.length; i++) {
-  lines.push(`declare function is${t.TYPES[i]}(node: Object, opts?: Object): boolean;`);
+  lines.push(
+    `declare function is${t.TYPES[i]}(node: Object, opts?: Object): boolean;`
+  );
 }
 
 for (const type in t.FLIPPED_ALIAS_KEYS) {
   const types = t.FLIPPED_ALIAS_KEYS[type];
-  code += `type ${NODE_PREFIX}${type} = ${types.map((type) => `${NODE_PREFIX}${type}`).join(" | ")};\n`;
+  code += `type ${NODE_PREFIX}${type} = ${types
+    .map(type => `${NODE_PREFIX}${type}`)
+    .join(" | ")};\n`;
 }
 
 code += `\ndeclare module "babel-types" {