From b63be942cef487fa31a7fa35bd7694076d5b7ad9 Mon Sep 17 00:00:00 2001
From: Karan Sapolia <karansapolia@users.noreply.github.com>
Date: Sat, 30 Jan 2021 23:06:21 +0530
Subject: [PATCH] Use native ESM for dev scripts (#12296)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com>
---
 .codesandbox/ci.json                          |  3 +-
 .eslintrc.js => .eslintrc.cjs                 | 15 ++++
 .github/workflows/ci.yml                      |  5 +-
 Gulpfile.js => Gulpfile.mjs                   | 77 ++++++++++---------
 Makefile                                      |  4 +-
 package.json                                  |  3 +-
 .../scripts/generators/asserts.js             |  9 +--
 .../scripts/generators/validators.js          | 15 ++--
 .../scripts/generators/virtual-types.js       |  8 +-
 packages/babel-traverse/scripts/package.json  |  1 +
 .../babel-types/scripts/generators/asserts.js |  7 +-
 .../scripts/generators/ast-types.js           | 10 +--
 .../scripts/generators/builders.js            | 16 ++--
 .../scripts/generators/constants.js           |  7 +-
 .../babel-types/scripts/generators/docs.js    | 36 ++++-----
 .../babel-types/scripts/generators/flow.js    |  8 +-
 .../scripts/generators/typescript-legacy.js   |  8 +-
 .../scripts/generators/validators.js          |  7 +-
 packages/babel-types/scripts/package.json     |  1 +
 .../scripts/utils/formatBuilderName.js        |  6 +-
 .../babel-types/scripts/utils/lowerFirst.js   |  5 +-
 .../scripts/utils/stringifyValidator.js       |  4 +-
 .../scripts/utils/toFunctionName.js           |  4 +-
 scripts/generators/readmes.js                 |  7 +-
 scripts/generators/tsconfig.js                | 13 +++-
 .../utils/bump-babel-dependencies.js          |  5 +-
 scripts/package.json                          |  1 +
 scripts/parser-tests/flow/index.js            | 15 ++--
 scripts/parser-tests/test262/index.js         | 13 ++--
 .../parser-tests/typescript/error-codes.js    |  2 +-
 scripts/parser-tests/typescript/index.js      | 17 ++--
 .../parser-tests/utils/parser-test-runner.js  | 10 +--
 scripts/rollup-plugin-babel-source.js         | 23 ++++--
 scripts/utils/formatCode.js                   | 25 ++----
 ...e-corejs3.mjs => babel-runtime-corejs3.js} |  0
 .../{babel-runtime.mjs => babel-runtime.js}   |  0
 test/esm/{index.mjs => index.js}              |  6 +-
 test/esm/package.json                         |  2 +-
 test/esm/{test-runner.mjs => test-runner.js}  |  0
 39 files changed, 205 insertions(+), 193 deletions(-)
 rename .eslintrc.js => .eslintrc.cjs (85%)
 rename Gulpfile.js => Gulpfile.mjs (87%)
 create mode 100644 packages/babel-traverse/scripts/package.json
 create mode 100644 packages/babel-types/scripts/package.json
 create mode 100644 scripts/package.json
 rename test/esm/{babel-runtime-corejs3.mjs => babel-runtime-corejs3.js} (100%)
 rename test/esm/{babel-runtime.mjs => babel-runtime.js} (100%)
 rename test/esm/{index.mjs => index.js} (62%)
 rename test/esm/{test-runner.mjs => test-runner.js} (100%)

diff --git a/.codesandbox/ci.json b/.codesandbox/ci.json
index f260124b7c..6b8111ffec 100644
--- a/.codesandbox/ci.json
+++ b/.codesandbox/ci.json
@@ -1,5 +1,6 @@
 {
   "buildCommand": "codesandbox:build",
   "sandboxes": ["7s08o", "vhm64"],
-  "packages": ["packages/*"]
+  "packages": ["packages/*"],
+  "node": "14"
 }
diff --git a/.eslintrc.js b/.eslintrc.cjs
similarity index 85%
rename from .eslintrc.js
rename to .eslintrc.cjs
index a900e19c0c..143e52e2d3 100644
--- a/.eslintrc.js
+++ b/.eslintrc.cjs
@@ -87,5 +87,20 @@ module.exports = {
         ],
       },
     },
+    {
+      files: ["packages/babel-traverse/scripts/**/*.js"],
+      rules: {
+        "import/no-extraneous-dependencies": [
+          "error",
+          { packageDir: "./packages/babel-traverse" },
+        ],
+      },
+    },
+    {
+      files: ["scripts/**/*.js"],
+      rules: {
+        "import/no-extraneous-dependencies": ["error", { packageDir: "." }],
+      },
+    },
   ],
 };
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7cc07c7baa..1ce79aa9da 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -65,8 +65,9 @@ jobs:
     name: Build Babel Artifacts
     needs: prepare-yarn-cache
     runs-on: ubuntu-latest
-    env:
-      YARN_NODE_LINKER: pnp # use pnp linker for better linking performance and stricter checks
+    # Yarn PnP does not support native ESM yet (https://github.com/yarnpkg/berry/issues/638)
+    # env:
+    #    YARN_NODE_LINKER: pnp # use pnp linker for better linking performance and stricter checks
     steps:
       - name: Checkout code
         uses: actions/checkout@v2
diff --git a/Gulpfile.js b/Gulpfile.mjs
similarity index 87%
rename from Gulpfile.js
rename to Gulpfile.mjs
index b9beb8b8ec..51feb35d5d 100644
--- a/Gulpfile.js
+++ b/Gulpfile.mjs
@@ -1,26 +1,33 @@
-"use strict";
+import path from "path";
+import fs from "fs";
+import { createRequire } from "module";
+import { fileURLToPath } from "url";
 
-const plumber = require("gulp-plumber");
-const through = require("through2");
-const chalk = require("chalk");
-const newer = require("gulp-newer");
-const babel = require("gulp-babel");
-const camelCase = require("lodash/camelCase");
-const fancyLog = require("fancy-log");
-const filter = require("gulp-filter");
-const gulp = require("gulp");
-const path = require("path");
-const fs = require("fs");
-const rollup = require("rollup");
-const rollupBabel = require("@rollup/plugin-babel").default;
-const rollupBabelSource = require("./scripts/rollup-plugin-babel-source");
-const rollupCommonJs = require("@rollup/plugin-commonjs");
-const rollupJson = require("@rollup/plugin-json");
-const rollupNodePolyfills = require("rollup-plugin-node-polyfills");
-const rollupNodeResolve = require("@rollup/plugin-node-resolve").default;
-const rollupReplace = require("@rollup/plugin-replace");
-const { terser: rollupTerser } = require("rollup-plugin-terser");
-const { default: rollupDts } = require("rollup-plugin-dts");
+import plumber from "gulp-plumber";
+import through from "through2";
+import chalk from "chalk";
+import newer from "gulp-newer";
+import babel from "gulp-babel";
+import camelCase from "lodash/camelCase.js";
+import fancyLog from "fancy-log";
+import filter from "gulp-filter";
+import gulp from "gulp";
+import { rollup } from "rollup";
+import { babel as rollupBabel } from "@rollup/plugin-babel";
+import rollupCommonJs from "@rollup/plugin-commonjs";
+import rollupJson from "@rollup/plugin-json";
+import rollupNodePolyfills from "rollup-plugin-node-polyfills";
+import rollupNodeResolve from "@rollup/plugin-node-resolve";
+import rollupReplace from "@rollup/plugin-replace";
+import { terser as rollupTerser } from "rollup-plugin-terser";
+import _rollupDts from "rollup-plugin-dts";
+const { default: rollupDts } = _rollupDts;
+
+import rollupBabelSource from "./scripts/rollup-plugin-babel-source.js";
+import formatCode from "./scripts/utils/formatCode.js";
+
+const require = createRequire(import.meta.url);
+const monorepoRoot = path.dirname(fileURLToPath(import.meta.url));
 
 const defaultPackagesGlob = "./@(codemods|packages|eslint)/*";
 const defaultSourcesGlob = `${defaultPackagesGlob}/src/**/{*.js,!(*.d).ts}`;
@@ -92,15 +99,16 @@ function rename(fn) {
  * @param {string} message
  */
 function generateHelpers(generator, dest, filename, message) {
-  const formatCode = require("./scripts/utils/formatCode");
   const stream = gulp
-    .src(".", { base: __dirname })
+    .src(".", { base: monorepoRoot })
     .pipe(errorsLogger())
     .pipe(
-      through.obj(function (file, enc, callback) {
+      through.obj(async (file, enc, callback) => {
+        const { default: generateCode } = await import(generator);
+
         file.path = filename;
         file.contents = Buffer.from(
-          formatCode(require(generator)(filename), dest + file.path)
+          formatCode(generateCode(filename), dest + file.path)
         );
         fancyLog(`${chalk.green("✔")} Generated ${message}`);
         callback(null, file);
@@ -119,7 +127,7 @@ function generateHelpers(generator, dest, filename, message) {
  */
 async function generateTypeHelpers(helperKind, filename = "index.ts") {
   return generateHelpers(
-    `./packages/babel-types/scripts/generators/${helperKind}`,
+    `./packages/babel-types/scripts/generators/${helperKind}.js`,
     `./packages/babel-types/src/${helperKind}/generated/`,
     filename,
     `@babel/types -> ${helperKind}`
@@ -133,7 +141,7 @@ async function generateTypeHelpers(helperKind, filename = "index.ts") {
  */
 async function generateTraverseHelpers(helperKind) {
   return generateHelpers(
-    `./packages/babel-traverse/scripts/generators/${helperKind}`,
+    `./packages/babel-traverse/scripts/generators/${helperKind}.js`,
     `./packages/babel-traverse/src/path/generated/`,
     `${helperKind}.ts`,
     `@babel/traverse -> ${helperKind}`
@@ -142,9 +150,8 @@ async function generateTraverseHelpers(helperKind) {
 
 function generateStandalone() {
   const dest = "./packages/babel-standalone/src/generated/";
-  const formatCode = require("./scripts/utils/formatCode");
   return gulp
-    .src(babelStandalonePluginConfigGlob, { base: __dirname })
+    .src(babelStandalonePluginConfigGlob, { base: monorepoRoot })
     .pipe(
       through.obj((file, enc, callback) => {
         fancyLog("Generating @babel/standalone files");
@@ -190,7 +197,7 @@ function finish(stream) {
 }
 
 function getFiles(glob, { include, exclude }) {
-  let stream = gulp.src(glob, { base: __dirname });
+  let stream = gulp.src(glob, { base: monorepoRoot });
 
   if (exclude) {
     const filters = exclude.map(p => `!**/${p}/**`);
@@ -206,7 +213,7 @@ function getFiles(glob, { include, exclude }) {
 }
 
 function buildBabel(exclude) {
-  const base = __dirname;
+  const base = monorepoRoot;
 
   return getFiles(defaultSourcesGlob, {
     exclude: exclude && exclude.map(p => p.src),
@@ -259,7 +266,7 @@ function buildRollup(packages, targetBrowsers) {
       }
       const input = getIndexFromPackage(src);
       fancyLog(`Compiling '${chalk.cyan(input)}' with rollup ...`);
-      const bundle = await rollup.rollup({
+      const bundle = await rollup({
         input,
         external,
         onwarn(warning, warn) {
@@ -352,7 +359,7 @@ function buildRollupDts(packages) {
     packages.map(async packageName => {
       const input = `${packageName}/lib/index.d.ts`;
       fancyLog(`Bundling '${chalk.cyan(input)}' with rollup ...`);
-      const bundle = await rollup.rollup({
+      const bundle = await rollup({
         input,
         plugins: [rollupDts()],
       });
@@ -378,7 +385,7 @@ function removeDts(exclude) {
 function copyDts(packages) {
   return getFiles(`${defaultPackagesGlob}/src/**/*.d.ts`, { include: packages })
     .pipe(rename(file => path.resolve(file.base, mapSrcToLib(file.relative))))
-    .pipe(gulp.dest(__dirname));
+    .pipe(gulp.dest(monorepoRoot));
 }
 
 const libBundles = [
diff --git a/Makefile b/Makefile
index 0061835a65..01097c6580 100644
--- a/Makefile
+++ b/Makefile
@@ -87,12 +87,12 @@ check-compat-data-ci:
 	$(MAKE) check-compat-data
 
 lint:
-	BABEL_ENV=test $(YARN) eslint scripts $(SOURCES) '*.{js,ts}' --format=codeframe --ext .js,.cjs,.mjs,.ts
+	BABEL_ENV=test $(YARN) eslint scripts $(SOURCES) '*.{js,cjs,mjs,ts}' --format=codeframe --ext .js,.cjs,.mjs,.ts
 
 fix: fix-json fix-js
 
 fix-js:
-	$(YARN) eslint scripts $(SOURCES) '*.{js,ts}' --format=codeframe --ext .js,.cjs,.mjs,.ts --fix
+	$(YARN) eslint scripts $(SOURCES) '*.{js,cjs,mjs,ts}' --format=codeframe --ext .js,.cjs,.mjs,.ts --fix
 
 fix-json:
 	$(YARN) prettier "{$(COMMA_SEPARATED_SOURCES)}/*/test/fixtures/**/options.json" --write --loglevel warn
diff --git a/package.json b/package.json
index 1f3220a649..42492b3d5a 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "version": "7.12.12",
   "private": true,
   "license": "MIT",
+  "type": "commonjs",
   "scripts": {
     "bootstrap": "make bootstrap",
     "codesandbox:build": "make build-no-bundle",
@@ -11,7 +12,7 @@
     "lint": "make lint",
     "test": "make test",
     "version": "yarn --immutable-cache && git add yarn.lock",
-    "test:esm": "node test/esm/index.mjs"
+    "test:esm": "node test/esm/index.js"
   },
   "devDependencies": {
     "@babel/cli": "^7.12.0",
diff --git a/packages/babel-traverse/scripts/generators/asserts.js b/packages/babel-traverse/scripts/generators/asserts.js
index 7f666c2307..f10b33eede 100644
--- a/packages/babel-traverse/scripts/generators/asserts.js
+++ b/packages/babel-traverse/scripts/generators/asserts.js
@@ -1,7 +1,6 @@
-"use strict";
-const t = require("@babel/types");
+import t from "@babel/types";
 
-module.exports = function generateAsserts() {
+export default function generateAsserts() {
   let output = `/*
  * This file is auto-generated! Do not modify it directly.
  * To re-generate run 'make build'
@@ -12,7 +11,7 @@ import NodePath from "../index";
 
 export interface NodePathAssetions {`;
 
-  for (const type of t.TYPES) {
+  for (const type of [...t.TYPES].sort()) {
     output += `
   assert${type}(
     opts?: object,
@@ -23,4 +22,4 @@ export interface NodePathAssetions {`;
 }`;
 
   return output;
-};
+}
diff --git a/packages/babel-traverse/scripts/generators/validators.js b/packages/babel-traverse/scripts/generators/validators.js
index b8a956057e..eae98a33e2 100644
--- a/packages/babel-traverse/scripts/generators/validators.js
+++ b/packages/babel-traverse/scripts/generators/validators.js
@@ -1,11 +1,8 @@
-"use strict";
+import t from "@babel/types";
+import virtualTypes from "../../lib/path/lib/virtual-types.js";
+import definitions from "@babel/types/lib/definitions/index.js";
 
-const t = require("@babel/types");
-const virtualTypes = require("../../lib/path/lib/virtual-types");
-
-const definitions = require("@babel/types/lib/definitions");
-
-module.exports = function generateValidators() {
+export default function generateValidators() {
   let output = `/*
  * This file is auto-generated! Do not modify it directly.
  * To re-generate run 'make build'
@@ -16,7 +13,7 @@ import NodePath from "../index";
 export interface NodePathValidators {
 `;
 
-  for (const type of t.TYPES) {
+  for (const type of [...t.TYPES].sort()) {
     output += `is${type}(opts?: object): this is NodePath<t.${type}>;`;
   }
 
@@ -34,4 +31,4 @@ export interface NodePathValidators {
 `;
 
   return output;
-};
+}
diff --git a/packages/babel-traverse/scripts/generators/virtual-types.js b/packages/babel-traverse/scripts/generators/virtual-types.js
index 504e32c953..6d55f54caa 100644
--- a/packages/babel-traverse/scripts/generators/virtual-types.js
+++ b/packages/babel-traverse/scripts/generators/virtual-types.js
@@ -1,8 +1,6 @@
-"use strict";
+import virtualTypes from "../../lib/path/lib/virtual-types.js";
 
-const virtualTypes = require("../../lib/path/lib/virtual-types");
-
-module.exports = function generateValidators() {
+export default function generateValidators() {
   let output = `/*
  * This file is auto-generated! Do not modify it directly.
  * To re-generate run 'make build'
@@ -23,4 +21,4 @@ export interface VirtualTypeAliases {
 `;
 
   return output;
-};
+}
diff --git a/packages/babel-traverse/scripts/package.json b/packages/babel-traverse/scripts/package.json
new file mode 100644
index 0000000000..5ffd9800b9
--- /dev/null
+++ b/packages/babel-traverse/scripts/package.json
@@ -0,0 +1 @@
+{ "type": "module" }
diff --git a/packages/babel-types/scripts/generators/asserts.js b/packages/babel-types/scripts/generators/asserts.js
index a517efb31a..bdfd94857f 100644
--- a/packages/babel-types/scripts/generators/asserts.js
+++ b/packages/babel-types/scripts/generators/asserts.js
@@ -1,5 +1,4 @@
-"use strict";
-const definitions = require("../../lib/definitions");
+import definitions from "../../lib/definitions/index.js";
 
 function addAssertHelper(type) {
   const result =
@@ -14,7 +13,7 @@ function addAssertHelper(type) {
   `;
 }
 
-module.exports = function generateAsserts() {
+export default function generateAsserts() {
   let output = `/*
  * This file is auto-generated! Do not modify it directly.
  * To re-generate run 'make build'
@@ -48,4 +47,4 @@ function assert(type: string, node: any, opts?: any): void {
   });
 
   return output;
-};
+}
diff --git a/packages/babel-types/scripts/generators/ast-types.js b/packages/babel-types/scripts/generators/ast-types.js
index 98122665de..c37cca5b07 100644
--- a/packages/babel-types/scripts/generators/ast-types.js
+++ b/packages/babel-types/scripts/generators/ast-types.js
@@ -1,9 +1,7 @@
-"use strict";
+import t from "../../lib/index.js";
+import stringifyValidator from "../utils/stringifyValidator.js";
 
-const t = require("../../");
-const stringifyValidator = require("../utils/stringifyValidator");
-
-module.exports = function generateAstTypes() {
+export default function generateAstTypes() {
   let code = `// NOTE: This file is autogenerated. Do not modify.
 // See packages/babel-types/scripts/generators/ast-types.js for script used.
 
@@ -118,7 +116,7 @@ export interface ${deprecatedAlias[type]} extends BaseNode {
   code += "}\n\n";
 
   return code;
-};
+}
 
 function hasDefault(field) {
   return field.default != null;
diff --git a/packages/babel-types/scripts/generators/builders.js b/packages/babel-types/scripts/generators/builders.js
index 6a528fe0c3..3a30e6053c 100644
--- a/packages/babel-types/scripts/generators/builders.js
+++ b/packages/babel-types/scripts/generators/builders.js
@@ -1,10 +1,8 @@
-"use strict";
-const definitions = require("../../lib/definitions");
-const formatBuilderName = require("../utils/formatBuilderName");
-const lowerFirst = require("../utils/lowerFirst");
-
-const t = require("../../");
-const stringifyValidator = require("../utils/stringifyValidator");
+import t from "../../lib/index.js";
+import definitions from "../../lib/definitions/index.js";
+import formatBuilderName from "../utils/formatBuilderName.js";
+import lowerFirst from "../utils/lowerFirst.js";
+import stringifyValidator from "../utils/stringifyValidator.js";
 
 function areAllRemainingFieldsNullable(fieldName, fieldNames, fields) {
   const index = fieldNames.indexOf(fieldName);
@@ -73,11 +71,11 @@ function generateBuilderArgs(type) {
   return args;
 }
 
-module.exports = function generateBuilders(kind) {
+export default function generateBuilders(kind) {
   return kind === "uppercase.js"
     ? generateUppercaseBuilders()
     : generateLowercaseBuilders();
-};
+}
 
 function generateLowercaseBuilders() {
   let output = `/*
diff --git a/packages/babel-types/scripts/generators/constants.js b/packages/babel-types/scripts/generators/constants.js
index 8e8b61c50b..68abdbd837 100644
--- a/packages/babel-types/scripts/generators/constants.js
+++ b/packages/babel-types/scripts/generators/constants.js
@@ -1,7 +1,6 @@
-"use strict";
-const definitions = require("../../lib/definitions");
+import definitions from "../../lib/definitions/index.js";
 
-module.exports = function generateConstants() {
+export default function generateConstants() {
   let output = `/*
  * This file is auto-generated! Do not modify it directly.
  * To re-generate run 'make build'
@@ -13,4 +12,4 @@ import { FLIPPED_ALIAS_KEYS } from "../../definitions";\n\n`;
   });
 
   return output;
-};
+}
diff --git a/packages/babel-types/scripts/generators/docs.js b/packages/babel-types/scripts/generators/docs.js
index 169894895b..18e536dd2f 100644
--- a/packages/babel-types/scripts/generators/docs.js
+++ b/packages/babel-types/scripts/generators/docs.js
@@ -1,10 +1,8 @@
-"use strict";
+import util from "util";
+import stringifyValidator from "../utils/stringifyValidator.js";
+import toFunctionName from "../utils/toFunctionName.js";
 
-const util = require("util");
-const stringifyValidator = require("../utils/stringifyValidator");
-const toFunctionName = require("../utils/toFunctionName");
-
-const types = require("../../");
+import t from "../../lib/index.js";
 
 const readme = [
   `# @babel/types
@@ -37,17 +35,13 @@ const customTypes = {
     key: "if computed then `Expression` else `Identifier | Literal`",
   },
 };
-Object.keys(types.BUILDER_KEYS)
+Object.keys(t.BUILDER_KEYS)
   .sort()
   .forEach(function (key) {
     readme.push("### " + key[0].toLowerCase() + key.substr(1));
     readme.push("```javascript");
     readme.push(
-      "t." +
-        toFunctionName(key) +
-        "(" +
-        types.BUILDER_KEYS[key].join(", ") +
-        ")"
+      "t." + toFunctionName(key) + "(" + t.BUILDER_KEYS[key].join(", ") + ")"
     );
     readme.push("```");
     readme.push("");
@@ -59,10 +53,10 @@ Object.keys(types.BUILDER_KEYS)
         "(node, opts)`."
     );
     readme.push("");
-    if (types.ALIAS_KEYS[key] && types.ALIAS_KEYS[key].length) {
+    if (t.ALIAS_KEYS[key] && t.ALIAS_KEYS[key].length) {
       readme.push(
         "Aliases: " +
-          types.ALIAS_KEYS[key]
+          t.ALIAS_KEYS[key]
             .map(function (key) {
               return "`" + key + "`";
             })
@@ -70,19 +64,19 @@ Object.keys(types.BUILDER_KEYS)
       );
       readme.push("");
     }
-    Object.keys(types.NODE_FIELDS[key])
+    Object.keys(t.NODE_FIELDS[key])
       .sort(function (fieldA, fieldB) {
-        const indexA = types.BUILDER_KEYS[key].indexOf(fieldA);
-        const indexB = types.BUILDER_KEYS[key].indexOf(fieldB);
+        const indexA = t.BUILDER_KEYS[key].indexOf(fieldA);
+        const indexB = t.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 defaultValue = t.NODE_FIELDS[key][field].default;
         const fieldDescription = ["`" + field + "`"];
-        const validator = types.NODE_FIELDS[key][field].validate;
+        const validator = t.NODE_FIELDS[key][field].validate;
         if (customTypes[key] && customTypes[key][field]) {
           fieldDescription.push(`: ${customTypes[key][field]}`);
         } else if (validator) {
@@ -99,11 +93,11 @@ Object.keys(types.BUILDER_KEYS)
             }
           }
         }
-        if (defaultValue !== null || types.NODE_FIELDS[key][field].optional) {
+        if (defaultValue !== null || t.NODE_FIELDS[key][field].optional) {
           fieldDescription.push(
             " (default: `" + util.inspect(defaultValue) + "`"
           );
-          if (types.BUILDER_KEYS[key].indexOf(field) < 0) {
+          if (t.BUILDER_KEYS[key].indexOf(field) < 0) {
             fieldDescription.push(", excluded from builder function");
           }
           fieldDescription.push(")");
diff --git a/packages/babel-types/scripts/generators/flow.js b/packages/babel-types/scripts/generators/flow.js
index 8a0a7b2635..7fabcc67c5 100644
--- a/packages/babel-types/scripts/generators/flow.js
+++ b/packages/babel-types/scripts/generators/flow.js
@@ -1,8 +1,6 @@
-"use strict";
-
-const t = require("../../");
-const stringifyValidator = require("../utils/stringifyValidator");
-const toFunctionName = require("../utils/toFunctionName");
+import t from "../../lib/index.js";
+import stringifyValidator from "../utils/stringifyValidator.js";
+import toFunctionName from "../utils/toFunctionName.js";
 
 const NODE_PREFIX = "BabelNode";
 
diff --git a/packages/babel-types/scripts/generators/typescript-legacy.js b/packages/babel-types/scripts/generators/typescript-legacy.js
index a77040681b..40da48f4e7 100644
--- a/packages/babel-types/scripts/generators/typescript-legacy.js
+++ b/packages/babel-types/scripts/generators/typescript-legacy.js
@@ -1,8 +1,6 @@
-"use strict";
-
-const t = require("../../lib");
-const stringifyValidator = require("../utils/stringifyValidator");
-const toFunctionName = require("../utils/toFunctionName");
+import t from "../../lib/index.js";
+import stringifyValidator from "../utils/stringifyValidator.js";
+import toFunctionName from "../utils/toFunctionName.js";
 
 let code = `// NOTE: This file is autogenerated. Do not modify.
 // See packages/babel-types/scripts/generators/typescript-legacy.js for script used.
diff --git a/packages/babel-types/scripts/generators/validators.js b/packages/babel-types/scripts/generators/validators.js
index c63d447bcd..acd6da6575 100644
--- a/packages/babel-types/scripts/generators/validators.js
+++ b/packages/babel-types/scripts/generators/validators.js
@@ -1,5 +1,4 @@
-"use strict";
-const definitions = require("../../lib/definitions");
+import definitions from "../../lib/definitions/index.js";
 
 const has = Function.call.bind(Object.prototype.hasOwnProperty);
 
@@ -62,7 +61,7 @@ function addIsHelper(type, aliasKeys, deprecated) {
   `;
 }
 
-module.exports = function generateValidators() {
+export default function generateValidators() {
   let output = `/*
  * This file is auto-generated! Do not modify it directly.
  * To re-generate run 'make build'
@@ -85,4 +84,4 @@ import type * as t from "../..";\n\n`;
   });
 
   return output;
-};
+}
diff --git a/packages/babel-types/scripts/package.json b/packages/babel-types/scripts/package.json
new file mode 100644
index 0000000000..5ffd9800b9
--- /dev/null
+++ b/packages/babel-types/scripts/package.json
@@ -0,0 +1 @@
+{ "type": "module" }
diff --git a/packages/babel-types/scripts/utils/formatBuilderName.js b/packages/babel-types/scripts/utils/formatBuilderName.js
index 621c468219..f00a3c4a61 100644
--- a/packages/babel-types/scripts/utils/formatBuilderName.js
+++ b/packages/babel-types/scripts/utils/formatBuilderName.js
@@ -1,10 +1,8 @@
-"use strict";
-
 const toLowerCase = Function.call.bind("".toLowerCase);
 
-module.exports = function formatBuilderName(type) {
+export default function formatBuilderName(type) {
   // FunctionExpression -> functionExpression
   // JSXIdentifier -> jsxIdentifier
   // V8IntrinsicIdentifier -> v8IntrinsicIdentifier
   return type.replace(/^([A-Z](?=[a-z0-9])|[A-Z]+(?=[A-Z]))/, toLowerCase);
-};
+}
diff --git a/packages/babel-types/scripts/utils/lowerFirst.js b/packages/babel-types/scripts/utils/lowerFirst.js
index 9e7b0cee51..012f252a7f 100644
--- a/packages/babel-types/scripts/utils/lowerFirst.js
+++ b/packages/babel-types/scripts/utils/lowerFirst.js
@@ -1,4 +1,3 @@
-"use strict";
-module.exports = function lowerFirst(string) {
+export default function lowerFirst(string) {
   return string[0].toLowerCase() + string.slice(1);
-};
+}
diff --git a/packages/babel-types/scripts/utils/stringifyValidator.js b/packages/babel-types/scripts/utils/stringifyValidator.js
index 2ea1e80357..4b8d29c12c 100644
--- a/packages/babel-types/scripts/utils/stringifyValidator.js
+++ b/packages/babel-types/scripts/utils/stringifyValidator.js
@@ -1,4 +1,4 @@
-module.exports = function stringifyValidator(validator, nodePrefix) {
+export default function stringifyValidator(validator, nodePrefix) {
   if (validator === undefined) {
     return "any";
   }
@@ -55,7 +55,7 @@ module.exports = function stringifyValidator(validator, nodePrefix) {
   }
 
   return ["any"];
-};
+}
 
 /**
  * Heuristic to decide whether or not the given type is a value type (eg. "null")
diff --git a/packages/babel-types/scripts/utils/toFunctionName.js b/packages/babel-types/scripts/utils/toFunctionName.js
index 627c9a7d8f..2b645780ec 100644
--- a/packages/babel-types/scripts/utils/toFunctionName.js
+++ b/packages/babel-types/scripts/utils/toFunctionName.js
@@ -1,4 +1,4 @@
-module.exports = function toFunctionName(typeName) {
+export default function toFunctionName(typeName) {
   const _ = typeName.replace(/^TS/, "ts").replace(/^JSX/, "jsx");
   return _.slice(0, 1).toLowerCase() + _.slice(1);
-};
+}
diff --git a/scripts/generators/readmes.js b/scripts/generators/readmes.js
index 07c358cbc1..a52041ac57 100644
--- a/scripts/generators/readmes.js
+++ b/scripts/generators/readmes.js
@@ -5,8 +5,11 @@
  * This script write the link to the website in every READMEs.
  */
 
-const { join } = require("path");
-const { readdirSync, writeFileSync } = require("fs");
+import { join } from "path";
+import { readdirSync, writeFileSync } from "fs";
+import { createRequire } from "url";
+
+const require = createRequire(import.meta.url);
 
 const cwd = process.cwd();
 
diff --git a/scripts/generators/tsconfig.js b/scripts/generators/tsconfig.js
index 1409cac9ac..eee32f516d 100644
--- a/scripts/generators/tsconfig.js
+++ b/scripts/generators/tsconfig.js
@@ -1,9 +1,14 @@
-"use strict";
+import path from "path";
+import fs from "fs";
+import { createRequire } from "module";
+import { fileURLToPath } from "url";
 
-const path = require("path");
-const fs = require("fs");
+const require = createRequire(import.meta.url);
 
-const root = path.resolve(__dirname, "../../");
+const root = path.resolve(
+  path.dirname(fileURLToPath(import.meta.url)),
+  "../../"
+);
 
 function getTsPkgs(subRoot) {
   return fs
diff --git a/scripts/integration-tests/utils/bump-babel-dependencies.js b/scripts/integration-tests/utils/bump-babel-dependencies.js
index f7509dcf63..528c7a9de2 100644
--- a/scripts/integration-tests/utils/bump-babel-dependencies.js
+++ b/scripts/integration-tests/utils/bump-babel-dependencies.js
@@ -1,5 +1,6 @@
-const fs = require("fs");
-const path = require("path");
+import fs from "fs";
+import path from "path";
+
 const cwd = process.cwd();
 const packageJSONPath = path.resolve(cwd, "./package.json");
 const content = JSON.parse(fs.readFileSync(packageJSONPath));
diff --git a/scripts/package.json b/scripts/package.json
new file mode 100644
index 0000000000..5ffd9800b9
--- /dev/null
+++ b/scripts/package.json
@@ -0,0 +1 @@
+{ "type": "module" }
diff --git a/scripts/parser-tests/flow/index.js b/scripts/parser-tests/flow/index.js
index af60022d7b..7b7e8a0b0c 100644
--- a/scripts/parser-tests/flow/index.js
+++ b/scripts/parser-tests/flow/index.js
@@ -1,7 +1,10 @@
-const fs = require("fs").promises;
-const path = require("path");
-const merge = require("mergeiterator");
-const TestRunner = require("../utils/parser-test-runner");
+import fs from "fs/promises";
+import path from "path";
+import { fileURLToPath } from "url";
+import merge from "mergeiterator";
+import TestRunner from "../utils/parser-test-runner.js";
+
+const dirname = path.dirname(fileURLToPath(import.meta.url));
 
 const flowOptionsMapping = {
   esproposal_class_instance_fields: "classProperties",
@@ -88,8 +91,8 @@ async function* loadTests(root) {
 }
 
 const runner = new TestRunner({
-  testDir: path.join(__dirname, "../../../build/flow/src/parser/test/flow"),
-  allowlist: path.join(__dirname, "allowlist.txt"),
+  testDir: path.join(dirname, "../../../build/flow/src/parser/test/flow"),
+  allowlist: path.join(dirname, "allowlist.txt"),
   shouldUpdate: process.argv.includes("--update-allowlist"),
 
   async *getTests() {
diff --git a/scripts/parser-tests/test262/index.js b/scripts/parser-tests/test262/index.js
index 9fe8141b9e..3c4d1856ad 100644
--- a/scripts/parser-tests/test262/index.js
+++ b/scripts/parser-tests/test262/index.js
@@ -1,6 +1,9 @@
-const path = require("path");
-const TestStream = require("test262-stream");
-const TestRunner = require("../utils/parser-test-runner");
+import path from "path";
+import { fileURLToPath } from "url";
+import TestStream from "test262-stream";
+import TestRunner from "../utils/parser-test-runner.js";
+
+const dirname = path.dirname(fileURLToPath(import.meta.url));
 
 const ignoredFeatures = [
   "__getter__",
@@ -163,8 +166,8 @@ function* getPlugins(features) {
 }
 
 const runner = new TestRunner({
-  testDir: path.join(__dirname, "../../../build/test262"),
-  allowlist: path.join(__dirname, "allowlist.txt"),
+  testDir: path.join(dirname, "../../../build/test262"),
+  allowlist: path.join(dirname, "allowlist.txt"),
   logInterval: 500,
   shouldUpdate: process.argv.includes("--update-allowlist"),
 
diff --git a/scripts/parser-tests/typescript/error-codes.js b/scripts/parser-tests/typescript/error-codes.js
index 16ce4eb71c..8274005ce3 100644
--- a/scripts/parser-tests/typescript/error-codes.js
+++ b/scripts/parser-tests/typescript/error-codes.js
@@ -8,7 +8,7 @@ Note that babel-parser should not throw for the TypeChecking Diagnostics
 The commented out diagnostic codes will introduce false positive cases that should be addressed in separate PRs.
 */
 
-module.exports = [
+export default [
   // "TS1005", // '{0}' expected.
   "TS1009", // Trailing comma not allowed.
   "TS1014", // A rest parameter must be last in a parameter list.
diff --git a/scripts/parser-tests/typescript/index.js b/scripts/parser-tests/typescript/index.js
index 36bd057cc9..52813b1658 100644
--- a/scripts/parser-tests/typescript/index.js
+++ b/scripts/parser-tests/typescript/index.js
@@ -1,8 +1,11 @@
-const path = require("path");
-const fs = require("fs").promises;
-const ts = require("../../../build/typescript");
-const TestRunner = require("../utils/parser-test-runner");
-const parsingErrorCodes = require("./error-codes");
+import path from "path";
+import fs from "fs/promises";
+import { fileURLToPath } from "url";
+import ts from "../../../build/typescript/lib/typescript.js";
+import TestRunner from "../utils/parser-test-runner.js";
+import parsingErrorCodes from "./error-codes.js";
+
+const dirname = path.dirname(fileURLToPath(import.meta.url));
 
 async function* loadTests(dir) {
   const names = await fs.readdir(dir);
@@ -21,7 +24,7 @@ const plugins = [
   "dynamicImport",
 ];
 
-const TSTestsPath = path.join(__dirname, "../../../build/typescript/tests");
+const TSTestsPath = path.join(dirname, "../../../build/typescript/tests");
 
 // Check if the baseline errors contain the codes that should also be thrown from babel-parser
 async function baselineContainsParserErrorCodes(testName) {
@@ -45,7 +48,7 @@ async function baselineContainsParserErrorCodes(testName) {
 
 const runner = new TestRunner({
   testDir: path.join(TSTestsPath, "./cases/compiler"),
-  allowlist: path.join(__dirname, "allowlist.txt"),
+  allowlist: path.join(dirname, "allowlist.txt"),
   logInterval: 50,
   shouldUpdate: process.argv.includes("--update-allowlist"),
 
diff --git a/scripts/parser-tests/utils/parser-test-runner.js b/scripts/parser-tests/utils/parser-test-runner.js
index 61b3ad16ef..79e235b48b 100644
--- a/scripts/parser-tests/utils/parser-test-runner.js
+++ b/scripts/parser-tests/utils/parser-test-runner.js
@@ -1,8 +1,6 @@
-"use strict";
-
-const fs = require("fs").promises;
-const chalk = require("chalk");
-const { parse: parser } = require("../../../packages/babel-parser");
+import fs from "fs/promises";
+import chalk from "chalk";
+import { parse as parser } from "../../../packages/babel-parser/lib/index.js";
 
 const dot = chalk.gray(".");
 
@@ -234,4 +232,4 @@ class TestRunner {
   }
 }
 
-module.exports = exports = TestRunner;
+export default TestRunner;
diff --git a/scripts/rollup-plugin-babel-source.js b/scripts/rollup-plugin-babel-source.js
index 7f4b794c37..5f4fbc49a7 100644
--- a/scripts/rollup-plugin-babel-source.js
+++ b/scripts/rollup-plugin-babel-source.js
@@ -1,20 +1,27 @@
-const path = require("path");
-const fs = require("fs");
-const dirname = path.join(__dirname, "..");
+import path from "path";
+import fs from "fs";
+import { fileURLToPath } from "url";
+import { createRequire } from "module";
+
+const require = createRequire(import.meta.url);
+const monorepoRoot = path.join(
+  path.dirname(fileURLToPath(import.meta.url)),
+  ".."
+);
 
 const BABEL_SRC_REGEXP =
   path.sep === "/"
     ? /packages\/(babel-[^/]+)\/src\//
     : /packages\\(babel-[^\\]+)\\src\\/;
 
-module.exports = function () {
+export default function () {
   return {
     name: "babel-source",
     load(id) {
       const matches = id.match(BABEL_SRC_REGEXP);
       if (matches) {
         // check if browser field exists for this file and replace
-        const packageFolder = path.join(dirname, "packages", matches[1]);
+        const packageFolder = path.join(monorepoRoot, "packages", matches[1]);
         const packageJson = require(path.join(packageFolder, "package.json"));
 
         if (
@@ -46,7 +53,7 @@ module.exports = function () {
     resolveId(importee) {
       if (importee === "@babel/runtime/regenerator") {
         return path.join(
-          dirname,
+          monorepoRoot,
           "packages",
           "babel-runtime",
           "regenerator",
@@ -61,7 +68,7 @@ module.exports = function () {
       const { pkg, internal } = matches.groups;
 
       // resolve babel package names to their src index file
-      const packageFolder = path.join(dirname, "packages", `babel-${pkg}`);
+      const packageFolder = path.join(monorepoRoot, "packages", `babel-${pkg}`);
 
       let packageJsonSource;
       try {
@@ -98,4 +105,4 @@ module.exports = function () {
       }
     },
   };
-};
+}
diff --git a/scripts/utils/formatCode.js b/scripts/utils/formatCode.js
index 0f14044016..ad42bde589 100644
--- a/scripts/utils/formatCode.js
+++ b/scripts/utils/formatCode.js
@@ -1,22 +1,9 @@
-"use strict";
+import prettier from "prettier";
 
-// TODO: Remove this `if` in Babel 8
-// Prettier only supports Node.js 10+, so we can fallback to not formatting
-// o CI on older Node.js versions
+export default function formatCode(code, filename) {
+  const prettierConfig = prettier.resolveConfig.sync(filename);
+  prettierConfig.filepath = filename;
+  prettierConfig.parser = filename.endsWith(".ts") ? "babel-ts" : "babel";
 
-if (process.env.CI && parseInt(process.versions.node, 10) < 10) {
-  module.exports = function formatCode(code) {
-    return code;
-  };
-} else {
-  const prettier = require("prettier");
-
-  module.exports = function formatCode(code, filename) {
-    filename = filename || __filename;
-    const prettierConfig = prettier.resolveConfig.sync(filename);
-    prettierConfig.filepath = filename;
-    prettierConfig.parser = filename.endsWith(".ts") ? "babel-ts" : "babel";
-
-    return prettier.format(code, prettierConfig);
-  };
+  return prettier.format(code, prettierConfig);
 }
diff --git a/test/esm/babel-runtime-corejs3.mjs b/test/esm/babel-runtime-corejs3.js
similarity index 100%
rename from test/esm/babel-runtime-corejs3.mjs
rename to test/esm/babel-runtime-corejs3.js
diff --git a/test/esm/babel-runtime.mjs b/test/esm/babel-runtime.js
similarity index 100%
rename from test/esm/babel-runtime.mjs
rename to test/esm/babel-runtime.js
diff --git a/test/esm/index.mjs b/test/esm/index.js
similarity index 62%
rename from test/esm/index.mjs
rename to test/esm/index.js
index 136eaeebb3..d4c33fc22c 100644
--- a/test/esm/index.mjs
+++ b/test/esm/index.js
@@ -1,6 +1,6 @@
-import babelRuntimeTestcases from "./babel-runtime.mjs";
-import babelRuntimeCorejs3Testcases from "./babel-runtime-corejs3.mjs";
-import testRunner from "./test-runner.mjs";
+import babelRuntimeTestcases from "./babel-runtime.js";
+import babelRuntimeCorejs3Testcases from "./babel-runtime-corejs3.js";
+import testRunner from "./test-runner.js";
 
 (async () => {
   await testRunner(babelRuntimeTestcases);
diff --git a/test/esm/package.json b/test/esm/package.json
index fffd18db4b..916edd5340 100644
--- a/test/esm/package.json
+++ b/test/esm/package.json
@@ -2,7 +2,7 @@
   "name": "@babel/test-esm",
   "private": true,
   "type": "module",
-  "exports": "./index.mjs",
+  "exports": "./index.js",
   "devDependencies": {
     "@babel/runtime": "workspace:*",
     "@babel/runtime-corejs3": "workspace:*",
diff --git a/test/esm/test-runner.mjs b/test/esm/test-runner.js
similarity index 100%
rename from test/esm/test-runner.mjs
rename to test/esm/test-runner.js