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The compiler for writing next generation JavaScript.
Check out our website: babeljs.io
For questions and support please visit our discussion forum, sign up for our Slack community, or StackOverflow.
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 issue urls now automatically redirect to their corresponding Github issue:
https://phabricator.babeljs.io/T2168 mostly corresponds to babel#2168.
Want to report an issue with babeljs.io (the website)?
For documentation and website issues please visit the babel/babel.github.iorepo.
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
The Babel repo is managed as a monorepo; it's composed of many npm 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.
| 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.
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.
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 are the heart of Babel and what make it work.
You can find community plugins on npm.
There are many kinds of plugins: ones that convert ES6/ES2015 to ES5, transform to ES3, minification, JSX, flow, experimental features, and more.
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): babel-plugin-syntax-x.
These are mostly for internal use in various plugins: babel-helper-x.
- 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)