The compiler for writing next generation JavaScript.

Docs?

Check out our website: babeljs.io

Looking for support?

For questions and support please visit our discussion forum, sign up for our Slack community, or StackOverflow.

Want to report a bug or request a feature?

Bugs and feature requests can be posted at https://github.com/babel/babel/issues.

We've moved our issues from phabricator back to github issues!

Former phabricator links are going to redirect to the corresponding Github issue, for example You can use http://phabricator.babeljs.io/T7567.

https://phabricator.babeljs.io/T2168
mostly corresponds to
https://github.com/babel/babel/issues/2168

Want to report an issue with babeljs.io (the website)?

For documentation and website issues please visit the babel/babel.github.iorepo.

Want to contribute to Babel?

Check out our CONTRIBUTING.md. If you have already joined slack, join our #development channel!

You can also start by checking out the issues with the help-wanted label.

Our discussions/notes/roadmap: babel/notes

Packages

The Babel repo is managed as a monorepo; it's composed of many npm packages.

Core Packages

Package	Version	Dependencies
babel-core
babylon
babel-traverse
babel-generator

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 (moved to a separate repo and versioned independently)
• The transformer[s]: All the plugins/presets
  • These all use babel-traverse to traverse through the AST
• The generator: babel-generator

The flow goes like this:

input string -> babylon parser -> AST -> transformer[s] -> AST -> babel-generator -> output string

Check out the babel-handbook for more information on this.

Other

Package	Version	Dependencies
babel-cli
babel-types
babel-polyfill
babel-runtime
babel-register
babel-template
babel-helpers
babel-code-frame

• 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). Check out the docs.
• babel-types is used to validate, build, change AST nodes.
• babel-polyfill is literally a wrapper around core-js and regenerator-runtime. Check out the docs.
• 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 (usually in library/plugin code). Check out the docs
• babel-register is a way to automatically compile files with babel on the fly by binding to node's require. Check out the docs
• babel-template is a helper function to make AST nodes. Instead you can pass a string representing the code you want to create rather than tediously building them using babel-types.
• babel-helpers is a set of premade babel-template functions that are used in some babel plugins.
• babel-code-frame is a standalone package used to generate errors that prints the source code and points to error locations.

Presets

After Babel 6, the default transforms were removed; if you don't specify any plugins/presets it will just return the original source code.

The transformer[s] used in Babel are the independent pieces of code that transform specific things. For example: the es2015-arrow-functions transform specifically changes arrow functions into a regular function. Presets are just simply an array of plugins that make it easier to run a whole a set of transforms without specifying each one manually.

There are a few presets that we maintain officially.

Package	Version	Dependencies
babel-preset-es2015
babel-preset-es2016
babel-preset-es2017
babel-preset-stage-0
babel-preset-stage-1
babel-preset-stage-2
babel-preset-stage-3
babel-preset-react

We maintain:

• a preset for each yearly release of ECMAScript (Javascript) starting from ES6/ES2015
• a preset for react (JSX/Flow)
• a preset for each stage (0-3) of the TC-39 Process for ECMAScript proposals.

You can find community maintained presets on npm

Plugins

Plugins are the heart of Babel and what make it work.

You can find community plugins on npm.

Transform Plugins

There are many kinds of plugins: ones that convert ES6/ES2015 to ES5, transform to ES3, minification, JSX, flow, experimental features, and more.

Package	Version	External Deps
babel-plugin-check-es2015-constants
babel-plugin-transform-async-functions
babel-plugin-transform-async-generator-functions
babel-plugin-transform-async-to-generator
babel-plugin-transform-async-to-module-method
babel-plugin-transform-class-properties
babel-plugin-transform-decorators
babel-plugin-transform-do-expressions
babel-plugin-transform-es2015-arrow-functions
babel-plugin-transform-es2015-block-scoped-functions
babel-plugin-transform-es2015-block-scoping
babel-plugin-transform-es2015-classes
babel-plugin-transform-es2015-computed-properties
babel-plugin-transform-es2015-destructuring
babel-plugin-transform-es2015-duplicate-keys
babel-plugin-transform-es2015-for-of
babel-plugin-transform-es2015-function-name
babel-plugin-transform-es2015-instanceof
babel-plugin-transform-es2015-literals
babel-plugin-transform-es2015-modules-amd
babel-plugin-transform-es2015-modules-commonjs
babel-plugin-transform-es2015-modules-systemjs
babel-plugin-transform-es2015-modules-umd
babel-plugin-transform-es2015-object-super
babel-plugin-transform-es2015-parameters
babel-plugin-transform-es2015-shorthand-properties
babel-plugin-transform-es2015-spread
babel-plugin-transform-es2015-sticky-regex
babel-plugin-transform-es2015-template-literals
babel-plugin-transform-es2015-typeof-symbol
babel-plugin-transform-es2015-unicode-regex
babel-plugin-transform-es3-member-expression-literals
babel-plugin-transform-es3-property-literals
babel-plugin-transform-es5-property-mutators
babel-plugin-transform-eval
babel-plugin-transform-exponentiation-operator
babel-plugin-transform-export-extensions
babel-plugin-transform-flow-comments
babel-plugin-transform-flow-strip-types
babel-plugin-transform-function-bind
babel-plugin-transform-jscript
babel-plugin-transform-object-assign
babel-plugin-transform-object-rest-spread
babel-plugin-transform-object-set-prototype-of-to-assign
babel-plugin-transform-proto-to-assign
babel-plugin-transform-react-constant-elements
babel-plugin-transform-react-display-name
babel-plugin-transform-react-inline-elements
babel-plugin-transform-react-jsx
babel-plugin-transform-react-jsx-compat
babel-plugin-transform-react-jsx-self
babel-plugin-transform-react-jsx-source
babel-plugin-transform-regenerator
babel-plugin-transform-runtime
babel-plugin-transform-strict-mode

Syntax Plugins

These just enable the transform plugins to be able to parse certain features (the transform plugins already include the syntax plugins so you don't need both).

Package	Version
babel-plugin-syntax-async-functions
babel-plugin-syntax-async-generators
babel-plugin-syntax-class-properties
babel-plugin-syntax-decorators
babel-plugin-syntax-do-expressions
babel-plugin-syntax-exponentiation-operator
babel-plugin-syntax-export-extensions
babel-plugin-syntax-flow
babel-plugin-syntax-function-bind
babel-plugin-syntax-function-sent
babel-plugin-syntax-jsx
babel-plugin-syntax-object-rest-spread

Helpers

These are mostly for internal use in plugins.

Package	Version	External Deps
babel-helper-bindify-decorators
babel-helper-builder-binary-assignment-operator-visitor
babel-helper-builder-conditional-assignment-operator-visitor
babel-helper-builder-react-jsx
babel-helper-call-delegate
babel-helper-define-map
babel-helper-explode-assignable-expression
babel-helper-explode-class
babel-helper-fixtures
babel-helper-function-name
babel-helper-get-function-arity
babel-helper-hoist-variables
babel-helper-optimise-call-expression
babel-helper-plugin-test-runner
babel-helper-regex
babel-helper-remap-async-to-generator
babel-helper-replace-supers
babel-helper-transform-fixture-test-runner

Misc

• babel the deprecated babel package on npm that was used in Babel 5.
• babel-messages a package to keep error messages, etc (not always used)

License

MIT