Yes, the output is uglier. But, this is necessary for me to refactor
`replaceSupers` for #7733, which is necessary for both #7555 and
https://github.com/babel/babel/pull/7553#issuecomment-381434519.
I'm still in the middle of cleaning up all this code. Don't expect
`transformClass` to survive much longer as it's written currently.
We were using `Object.create` to setup the prototype chain at the start of the class definition, which lead to #7771.
I was a bit worried about a speed hit, but it seems everyone optimizes the two patterns the same way.
https://jsbench.github.io/#f9fca52407643d96458a35763b201215Fixes#7771.
* Implement MemberExpressionToFunctions helper
Fixes#7733.
This will also be used to simplify the Private Fields transform, which had [almost the same code](ccd941057a/packages/babel-plugin-proposal-class-properties/src/index.js (L114-L217)) hand written.
* Cleanup
* Little more comment cleanup
* Use unary plus
This can't be redefined, unlike the `Number` identifier.
* Review comments
* Remove unused deps
* drop support for Node.js v4; closes#7753
- remove version 4 from Travis build matrix
- update environment support doc
- update `CONTRIBUTING.md`
- update `engines` field of root `package.json`
Signed-off-by: Christopher Hiller <boneskull@boneskull.com>
* update engines for babylon
Signed-off-by: Christopher Hiller <boneskull@boneskull.com>
* Improve asyncIterator error
When an object is has neither asyncIterator or iterator defined, throw the "not an async iterable" error
* Correct logic
* reduce access
* Update helpers.js
* Update decorators parsing
This commit introduces three changes:
1) Class properties can be decorated
2) Decorators can contain arbitrary expressions, using @(...)
3) The Decorator node type has a new property, "arguments". This
makes it possible do distinguish @dec() and @(dec()), which have
different behaviors because @(dec()) is equivalent to @(dec())().
* Rename Decorator#expression to Decorator#callee
* Add test for @dec()()
* Fix class properties after nested class' bare super
Fixes#7371.
* Fix node 4 test
* This damn node 4 test
* All of the ClassBody, but not the methods or field inits
* tmp
* tmp
* Use common class environment visitor
* Tests
* Use skipKey to avoid recursive traversal
* Remove old state
* Use jest expect
* Properly traverse nested class for supers
* Add object nested in class cases
* Add object nested object cases
* Test class properties
* Undo changes to lerna.json
* Add tests arournd prefix/postfix super increment
* tmp
* Use sets
* Improve get/set helper
* fixtures
* Edge cases
* Add loose edge cases
* Spec compliant
* Add issue case
* Even more edge cases!
* Final updates
* Fix name
* Use Reflect.{get, set} when available
* Avoid block scoping in loose
* Remove semicolon
* Do not redefine a non-enumerable
* Get strictness from call site, not helpers
* Add called assertions
* Classes are always strict
* Update test fixture
* #7349
- Add "use strict" directive to transformed class bodies
* Update tests (#7349)
* Add test for program with use strict directive (#7349)
* Update tests (#7349)
* Update source mapping (#7349)
* Add test for parent blockStatement with use strict directive (#7349)
* Update tests (#7349)
* Update tests (#7349)
* Update tests (#7349)
* Add test for constructor-only class (#7349)
* Constructor only classes are strict, too
But constructor only that use non-simple parameters must use a strict function wrapper.
* Fix test
* Wrapper not needed if class is already strict
* Revert change to lerna.json
Added the value argument to the visitors of flow literal type
annotations.
Literal type annotations need a value since they work very much like
primitive literals in normal JavaScript.
Fixes#7697
* Fix name computation for literal values
* Add more computed literal test cases
* Always return a string in getNameFromLiteralId
- Also concatenate quasis id for regex literal
* Add a test clarifying function name for template literals
* Remove useless else ifs
It was needed to avoid collision of identifiers used in fields
initializers with variables declared in the constructor, but it
broke `this` handling.
This commit removes that behavior and instead renames the
colliding variables.
* Add support for RegExp includes/excludes
* Keep the plugin order
* Detect invalid modules in regexp
* Add more tests for regexp
* Cover builtins, and unnormalized in the RegExp tests
* Remove babel-plugin- in all positions
* Change babel-plugin- prefix to string
* Add a test for the same module in include/exclude
* Handle partial matches explicitly
* Remove extra valid regexp check
* Optimise validation of plugins
* Optimise selecting the plugins
* Fix undefined include/exclude option
* Update documentation to reflect the new include matching
* Fix typo
* Apply reviews
Use regexp.test instead of string.match (slower)
Define flatten helper
Do not normalize babel-plugin anywhere in the string
These files appear to have been missed in the update of test file naming from actual/expected.js to input/output.js. As a result, they were silently not being run. I've confirmed that they were not running, updated the names, then confirmed that they are running now.
The boolean expressions returns false in environments where Map is missing.
This change explicitly sets _cache to undefined in such cases, to ensure the cache methods will be ignored.
* docs(babel-standalone): remove bower mention
Since the package won't be downloadable as `@babel/standalone` it's best to just remove it, since it's pretty much deprecated as is. I left the other mention of babel-standalone-bower since I guess that's just the name and still useful in other cases
cc @daniel15
reported in https://github.com/babel/babel/pull/6495#pullrequestreview-70980926
* Update README.md
* Update test262 and whitelist
* Use test262-stream
* Check escapes in contextual keywords
* Check escapes when parsing new.target
* Check escapes for getters/setters
* Check escapes for static class methods
* Check escapes on async arrow and functions
* .prettierrc: full configuration for Prettier
This way, contributors using different-from-default settings will still
use the correct prettier settings
* Makefile: also lint .babelrc.js
* Makefile: also prettify .json files
* Exclude package.json files and correct build dir
* Add more default options to prettierrc and load it in cli
This avoids prettier looking up the config for each file
* Format json
* Update prettier and eslint and reformat codebase
* Remove obsolete file
* Add comment
* Fix reseting modules in jest and config
we have lib folders inside the source folders which should not be ignored.
* Add codemods lib folder
* Support mjs
* improve ignore pattern
for-await was transformed in @babel/helper-remap-async-to-generator, which was
called by @babel/plugin-transform-async-to-generator and
@babel/plugin-proposal-async-generator-functions. This prevented for-await
statements in async functions to be transpiled if the
transform-async-to-generator plugin was't enabled.
* feat(babel-cli): add a brief summary to build output
* address feedback
* further adjustments
* Use quiet output as default, add --verbose
* fix tests
* remove verbose alias
Prior to this change, we'd conduct an open-ended traversal on the 'id'
of any VariableDeclarator to find a RestElement. The 'id' of
a VariableDeclarator can contain an AssignmentPattern (to supply
a default value), and if the right-hand side of the AssignmentPattern
contained a RestElement, we'd transform it.
The problem here is that the right-hand side of an AssignmentPattern can
be *any* Expression. If the right-hand side is a function body, we'd
traverse the entire function body, and if a RestElement occurred
anywhere in that function body, we'd transform it and emit the
transformations wherever we began the traversal (at least one scope
outside its usage).
The fix is to stop the inner traversal if we encounter an
AssignmentPattern. The outer traversal will still visit the
AssignmentPattern, so RestElements within the right-hand side of an
AssignmentPattern will be properly transformed at that time.
This creates a new package called @babel/highlight which syntax highlights
JavaScript code for terminal output. This functionality was already
present in @babel/code-frame, but exposing it as a separate package lets
other projects leverage it. @babel/code-frame has been refactored
slightly so that it uses @babel/highlight to do its syntax highlighting.
* Added optionalExpression types to babylon and babel-types
* OptionalChain transforms bug fix
* Added OptionalExpressions to babel-generator. Fixed OptionalChain Bugs
* Removed 'optionalChain' from newExpression and added test cases
* Added test cases for optionalChain
* Update index.js
This failing test case demonstrates a regression between 7.0.0-beta.38 and
7.0.0-beta.39 in the @babel/plugin-proposal-object-rest-spread package.
I distilled this test case from a larger configuration of plugins in my
application, one of which calls api.traverse.cache.clearScope(). Although
calling clearScope() is an uncommon thing for a plugin to do, it was a
reliable way to reproduce the problem. If I can find other reliable
reproductions, I'll push some additional failing tests to this PR.
Regardless of how common it is, clearing the scope cache should be a safe
operation that only slows down the transform (because scopes have to be
recreated and re-crawled). Crashing due to a spurious duplicate
declaration seems like a bug worth fixing.
My hunch is that [these two lines](eb38ea2b10/packages/babel-plugin-proposal-object-rest-spread/src/index.js (L75-L76))
(which were changed in `7.0.0-beta.39`) are not actually removing the
original rest element as a binding from the enclosing `Scope`, in certain
circumstances, so the new variable declaration ends up colliding with the
old (removed) binding.
Possibly related: #7304 (reported by @julien-f)
* generate typescript types
* improve type generator output
* move generator scripts to scripts/generators
* use new stringifier for generating flow types too
* export summary types
* add support for oneOfNodeOrValueTypes to improve type generation
* export typescript types from top level, and remove module declaration
* generate typescript/flow types and copy typescript types to babel-types/lib as part of make build
* copy flow types to babel-types/lib as part of make build (fix#6839)
* improve typing: Identifier->name should be a string, not any
* avoid destructuring, to support node 4
* update doc generator to share more code, regenerate babel-types readme, pipe all generator output to stdout
* regenerate babel-types readme as part of make build
* improve typing: ClassProperty->key should be Identifier | StringLiteral | NumericLiteral | Expression, not any
* improve typing: optional node properties are nullable, not undefinedable
* improve docs: FlowClassImplements should be ClassImplements
* make ts usage more friendly: when using babel-types api, make optional params | undefined, and when reading nodes keep optional params | null
* rm lib/types.d.ts and lib/types.js in favor of packages/babel-types/lib
* add missing variance node type, address review comments
* add tests for flow variance
* Comment should be a disjoint union of tagged types
* update .flowconfig
Keeping the shape of an object constant is a performance improvement for modern javascript engines. At the point of the code change it is certain that the `children` property will be set later, so the property can already be set to `undefined`.
* use the async version of transform in babel-cli
* Modify compile to use async version of transformFile
* Babel-CLI: transform files sequentially
* Remove useless res in callback
* Add test case for simple reference in tdz
* Add more examples from old issues as test cases
* Fix two testcases by excluding function declarations from being tdz checked
* Document the option for block-scoping
* Add test cases with destructuring assignments
* Remove failing test cases
* [skip ci] Include type and default value for options
* Bail out on JSX fragments instead of throwing
The `transform-react-inline-elements` plugin doesn't handle JSX fragments. It throws an exception because `node.openingElement` is undefined.
* Add a comment explaining `node.openingElement`
* Update line endings in test fixtures to match current output
* Fix incorrectly set up static-property-tdz fixtures
It seems the fixture runner does not look into subfolders.
* Remove expected file that should not exist
* Reenable disable optimisation test
* Reenable disabled nbsp tests
* Reenable comments between props test
The comments adjacent to children test is still broken so it stays off.
* Avoid adding #__PURE__ annotation to .bind(this)() expressions
Fixes the #__PURE__ annotation getting added to (async () => {})() IIFEs when the arrow function transform is running with spec: true.
* Return false instead of undefined
* Fix indentation in json files
* Add one more case to the async-iife fixtures
* Better error messages when Babel fails to parse import = and export = syntax from typescript when using babel-plugin-transform-typescript
* Fixing Test cases
* Ran make fix and broken looong sentence into smaller
* Slight changes to Messages after review with Nicolo & existentialism
* Removed trailing space
* Handling babylon parsing errors in a better way
* Better error messages + Helpful URLs
* Replaced message from babylon completely
* Add importMeta plugin to the map
Currently, Babel is treating JSXIdentifier, JSXMemberExpression, and JSXEmptyExpression as expressions as well, which means Babel will for example incorrectly allow you to place these anywhere an expression is wanted.
Closes#6851.
`this.blockPath.get("body")` constructs an array of paths corresponding to each node in `blocks.body` so takes O(n) time if n is that length. We were re-constructing that array on each iteration, so the entire loop was O(n^2).
On files with many statements in a single block (such as Rollup-generated bundles), this takes a large portion of time. In particular, this makes transforming react-dom.development.js about 40% faster. Not that you should be transforming our bundle with Babel.
Test Plan:
Make an HTML file with these three lines and watch it in the Chrome Performance tab to see timings (on my machine: 2.9s before, 1.6s after):
```
<!DOCTYPE html>
<script src="https://unpkg.com/babel-standalone@7.0.0-beta.3/babel.js"></script>
<script type="text/babel" src="https://unpkg.com/react-dom@16.2.0/umd/react-dom.development.js"></script>
```
This commit introduces 4 changes:
1) Function declarations are wrapped using function declarations.
This has two advantages:
- We can rely on native hoisting, instead of using _blockHoist
- The function isn't wrapped until it is called. This avoids
problems where `regeneratorRuntime.wrap` was called before
that `babel-polyfill` was imported.
Example:
function fn() {}
// becomes
function fn() { return _fn.apply(this, arguments); }
function _fn() {
_fn = _wrapper(/* Original function ... */);
return _fn.apply(this, arguments);
}
2) Use a single template for both named and anonymous function
expressions. They already had the same behavior, but the one
used for named functions was a bit longer.
3) Use normal functions instead of arrow functions to wrap
function expressions.
4) Generate a name based on the original one for wrapped
functions (e.g. `foo` becomes `_foo` instead of `_ref`).
- Check out [the Babel Plugin Handbook](https://github.com/thejameskyle/babel-handbook/blob/master/translations/en/plugin-handbook.md#babel-plugin-handbook) - core plugins are written the same way as any other plugin!
- Check out [AST Explorer](http://astexplorer.net/#/scUfOmVOG5) to learn more about ASTs or make your own plugin in the browser
- When you feel ready to jump into the Babel source code, a good place to start is to look for issues tagged with [help wanted](https://github.com/babel/babel/labels/help%20wanted) and/or [good first issue](https://github.com/babel/babel/labels/good%20first%20issue).
- Follow along with what we are working on by joining our Slack, following our announcements on [Twitter](https://twitter.com/babeljs), and reading (or participating!) in our [meeting notes](https://github.com/babel/notes).
- Follow along with what we are working on by joining our [Slack](https://babeljs.slack.com) (you can sign-up [here](https://slack.babeljs.io/)
for an invite), following our announcements on [Twitter](https://twitter.com/babeljs), and reading (or participating!) in our [meeting notes](https://github.com/babel/notes).
- Check out our [website](http://babeljs.io/) and the [repo](https://github.com/babel/website)
## Chat
Feel free to check out the `#discussion`/`#development` channels on our [Slack](https://slack.babeljs.io). Some of us are always online to chat!
Feel free to check out the `#discussion`/`#development` channels on our [Slack](https://slack.babeljs.io) (you can sign-up [here](https://slack.babeljs.io/) for an invite). Some of us are always online to chat!
## Developing
**Note:** Versions `< 5.1.10` can't be built.
Babel is built for Node 4 and up but we develop using Node 8 and yarn. You can check this with `node -v`.
Babel is built for Node 6 and up but we develop using Node 8 and yarn. You can check this with `node -v`.
Make sure that Yarn is installed with version >= `0.28.0`.
Installation instructions can be found here: https://yarnpkg.com/en/docs/install.
@@ -116,7 +117,7 @@ $ TEST_ONLY=babel-cli make test
```sh
# Run tests for the @babel/plugin-transform-classes package.
$ TEST_ONLY=es2015-class make test
$ TEST_ONLY=babel-plugin-transform-classes make test
```
Use the `TEST_GREP` variable to run a subset of tests by name:
@@ -139,6 +140,12 @@ $ TEST_DEBUG=true make test
You can combine `TEST_DEBUG` with `TEST_GREP` or `TEST_ONLY` to debug a subset of tests. If you plan to stay long in the debugger (which you'll likely do!), you may increase the test timeout by editing [test/mocha.opts](https://github.com/babel/babel/blob/master/test/mocha.opts).
To overwrite any test fixtures when fixing a bug or anything, add the env variable `OVERWRITE=true`
```sh
$ OVERWRITE=trueTEST_ONLY=babel-plugin-transform-classes make test-only
```
To test the code coverage, use:
```sh
@@ -175,29 +182,29 @@ For example, in [`@babel/plugin-transform-exponentiation-operator/test`](https:/
- In each subfolder, you can organize your directory structure by categories of tests. (Example: these folders can be named after the feature you are testing or can reference the issue number they fix)
- Generally, there are two kinds of tests for plugins
- The first is a simple test of the input and output produced by running Babel on some code. We do this by creating an [`actual.js`](https://github.com/babel/babel/blob/master/packages/babel-plugin-transform-exponentiation-operator/test/fixtures/exponentian-operator/binary/actual.js) file and an [`expected.js`](https://github.com/babel/babel/blob/master/packages/babel-plugin-transform-exponentiation-operator/test/fixtures/exponentian-operator/binary/expected.js) file.
- If you need to expect an error, you can ignore creating the `expected.js` file and pass a new `throws` key to the `options.json` that contains the error string that is created.
- The first is a simple test of the input and output produced by running Babel on some code. We do this by creating an [`input.js`](https://github.com/babel/babel/blob/master/packages/babel-plugin-transform-exponentiation-operator/test/fixtures/exponentian-operator/binary/input.js) file and an [`output.js`](https://github.com/babel/babel/blob/master/packages/babel-plugin-transform-exponentiation-operator/test/fixtures/exponentian-operator/binary/output.js) file. This kind of test only works in sub-subdirectories of `/fixtures`, i.e. `/fixtures/exponentian-operator/binary/input.js` and **not**`/fixtures/exponentian-operator/input.js`.
- If you need to expect an error, you can ignore creating the `output.js` file and pass a new `throws` key to the `options.json` that contains the error string that is created.
- The second and preferred type is a test that actually evaluates the produced code and asserts that certain properties are true or false. We do this by creating an [`exec.js`](https://github.com/babel/babel/blob/master/packages/babel-plugin-transform-exponentiation-operator/test/fixtures/exponentian-operator/comprehensive/exec.js) file.
In an actual/expected test, you simply write out the code you want transformed in `actual.js`.
In a fixture test, you simply write out the code you want transformed in `input.js`.
```js
// actual.js
// input.js
2**2;
```
and the expected output after transforming it with your `options.json` in `expected.js`.
and the expected output after transforming it with your `options.json` in `output.js`.
```js
// expected.js
// output.js
Math.pow(2,2);
```
In an `exec.js` test, we run or check that the code actually does what it's supposed to do rather than just check the static output.
```js
// exec.js
assert.equal(8,2**3);
assert.equal(24,3*2**3);
expect(2**3).toBe(8);
expect(3*2**3).toBe(24);
```
If you need to check for an error that is thrown you can add to the `options.json`
@@ -227,14 +234,14 @@ Inside the `packages/babylon/tests/fixtures` folder are categories/groupings of
etc.). To add a test, create a folder under one of these groupings (or create a new one) with a
descriptive name, and add the following:
* Create an `actual.js` file that contains the code you want Babylon to parse.
* Create an `input.js` file that contains the code you want Babylon to parse.
* Add an `expected.json` file with the expected parser output. For added convenience, if there is no `expected.json` present, the test runner will generate one for you.
* Add an `output.json` file with the expected parser output. For added convenience, if there is no `output.json` present, the test runner will generate one for you.
After writing tests for babylon, just build it by running:
```sh
$ make build-babylon
$ make build
```
Then, to run the tests, use:
@@ -245,7 +252,7 @@ $ TEST_ONLY=babylon make test-only
#### Bootstrapping expected output
For both `@babel/plugin-x` and `babylon`, you can easily generate an `expected.js`/`expected.json` automatically by just providing `actual.js` and running the tests as you usually would.
For both `@babel/plugin-x` and `babylon`, you can easily generate an `output.js`/`output.json` automatically by just providing `input.js` and running the tests as you usually would.
```
// Example
@@ -256,8 +263,8 @@ For both `@babel/plugin-x` and `babylon`, you can easily generate an `expected.j
- comments
- basic
- block-trailing-comment
- actual.js
- expected.json (will be generated if not created)
- input.js
- output.json (will be generated if not created)
```
### Debugging code
@@ -309,7 +316,7 @@ Note that the code shown in Chrome DevTools is compiled code and therefore diffe
- Compiler environment support ([doc/design/compiler-environment-support.md](https://github.com/babel/babel/blob/master/doc/design/compiler-environment-support.md))
Babel is community-driven and thus mostly maintained by a group of [volunteers](https://babeljs.io/team). It has a lot of [companies and projects](https://babeljs.io/users) using it but almost no sponsors/people funded to work on it. If you'd like to help maintain the future of the project, please consider:
Babel is a community-driven project used by many companies and projects, and is maintained by a group of [volunteers](https://babeljs.io/team). If you'd like to help support the future of the project, please consider:
- Giving developer time on the project. (Message us on [Twitter](https://twitter.com/babeljs) or [Slack](https://slack.babeljs.io/))
-[Giving funds by becoming a backer/sponsor on OpenCollective](https://opencollective.com/babel)
- Giving developer time on the project. (Message us on [Twitter](https://twitter.com/babeljs) or [Slack](https://slack.babeljs.io/) for guidance!)
- Giving funds by becoming a sponsor (see below)!
## Open Collective Sponsors
Become a sponsor and get your logo on our README on Github with a link to your site. [[Become a sponsor](https://opencollective.com/babel#sponsor)]
@@ -50,11 +100,6 @@ Babel is a tool that helps you write code in the latest version of JavaScript. W
Try it out at our [REPL](https://babeljs.io/repl/build/master#?code_lz=NoRgNATGDMC6B0BbAhgBwBQDsAEBeAfNjgNTYgCUA3EA&lineWrap=true&presets=es2015%2Ces2016%2Ces2017&version=7.0.0-beta.2).
- [FAQ](#faq)
- [Backers](#backers)
- [Sponsors](#sponsors)
- [License](#license)
## FAQ
### Who maintains Babel?
@@ -63,7 +108,11 @@ Mostly a handful of volunteers! Please check out our [team page](https://babeljs
### Looking for support?
For questions and support please visit join our [Slack Community](https://slack.babeljs.io/), ask a question on [Stack Overflow](https://stackoverflow.com/questions/tagged/babeljs), or ping us on [Twitter](https://twitter.com/babeljs).
For questions and support please visit join our [Slack Community](https://slack.babeljs.io/) (you can sign-up [here](https://slack.babeljs.io/) for an invite), ask a question on [Stack Overflow](https://stackoverflow.com/questions/tagged/babeljs), or ping us on [Twitter](https://twitter.com/babeljs).
### Is there a Babel song?
I'm so glad you asked: [Hallelujah —— In Praise of Babel](SONG.md) by [@angus-c](https://github.com/angus-c). Tweet us your recordings!
### Where are the docs?
@@ -86,76 +135,6 @@ Check out our [CONTRIBUTING.md](CONTRIBUTING.md) to get started with setting up
The Babel repo is managed as a [monorepo](doc/design/monorepo.md) that is composed of many [npm packages](packages/README.md).
## Backers
Support us with a monthly donation and help us continue our activities. [[Become a backer](https://opencollective.com/babel#backer)]
[`@babel/core`](/packages/babel-core) is the Babel compiler itself; it exposes the `babel.transform` method, where `transformedCode = transform(src).code`.
The compiler can be broken down into 3 parts:
- The parser: [`babylon`](https://github.com/babel/babel/tree/master/packages/babylon)
- The parser: [`babylon`](/packages/babylon)
- The transformer[s]: All the plugins/presets
- These all use [`@babel/traverse`](/packages/babel-traverse) to traverse through the AST
- The generator: [`@babel/generator`](/packages/babel-generator)
@@ -36,18 +36,18 @@ Check out the [`babel-handbook`](https://github.com/thejameskyle/babel-handbook/
- [`@babel/cli`](/packages/babel-cli) is the CLI tool that runs `@babel/core` and helps with outputting to a directory, a file, stdout and more (also includes `@babel/node` cli). Check out the [docs](https://babeljs.io/docs/usage/cli/).
- [`@babel/types`](/packages/babel-types) is used to validate, build and change AST nodes.
- [`@babel/polyfill`](/packages/babel-polyfill) is [literally a wrapper](https://github.com/babel/babel/blob/master/packages/babel-polyfill/src/index.js) around [`core-js`](https://github.com/zloirock/core-js) and [regenerator-runtime](https://github.com/facebook/regenerator/tree/master/packages/regenerator-runtime). Check out the [docs](https://babeljs.io/docs/usage/polyfill/).
- [`@babel/polyfill`](/packages/babel-polyfill) is [literally a wrapper](/packages/babel-polyfill/src/index.js) around [`core-js`](https://github.com/zloirock/core-js) and [regenerator-runtime](https://github.com/facebook/regenerator/tree/master/packages/regenerator-runtime). Check out the [docs](https://babeljs.io/docs/usage/polyfill/).
- [`@babel/runtime`](/packages/babel-runtime) is similar to the polyfill except that it doesn't modify the global scope and is to be used with [`@babel/plugin-transform-runtime`](/packages/babel-plugin-transform-runtime) (usually in library/plugin code). Check out the [docs](https://babeljs.io/docs/plugins/transform-runtime/).
- [`@babel/register`](/packages/babel-register) is a way to automatically compile files with Babel on the fly by binding to Node.js `require`. Check out the [docs](http://babeljs.io/docs/usage/require/).
- [`@babel/template`](/packages/babel-template) is a helper function that allows constructing AST nodes from a string presentation of the code; this eliminates the tedium of using `@babel/types` for building AST nodes.
@@ -62,7 +62,7 @@ The transformer[s] used in Babel are the independent pieces of code that transfo
| Package | Version | Dependencies | Description |
|--------|-------|------------|---|
| [`@babel/preset-env`](https://github.com/babel/babel-preset-env) | [](https://www.npmjs.com/package/babel-preset-env) | [](https://david-dm.org/babel/babel-preset-env) | automatically determines plugins and polyfills you need based on your supported environments |
| [`@babel/preset-env`](/packages/babel-preset-env) | [](https://www.npmjs.com/package/@babel/preset-env) | [](https://david-dm.org/babel/babel?path=packages/babel-preset-env) | automatically determines plugins and polyfills you need based on your supported environments |
> You can find community maintained presets on [npm](https://www.npmjs.com/search?q=babel-preset)
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