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Transform next-generation JavaScript to today's JavaScript.

README.md

esnext

Gitter

Use tomorrow's JavaScript syntax today. Try it now in your browser.

NOTE: This project has merged with Babel.

esnext has merged with Babel. All the features of esnext are supported by Babel, and more. All the tests from esnext have been ported over to Babel to ensure that switchers will have minimal code changes to make. The maintainers of esnext will continue working on Babel to bring better spec compliance, ES6 feature support, and performance.

Transition Notes

When transitioning your project from esnext to Babel, you'll need to do different things depending on how you brought esnext into your project.

I have a direct dependency on the esnext npm package.

You'll need to remove the esnext entry from your package.json and add Babel in its place, using the Babel API or CLI instead of esnext's.

I'm using esnext with broccoli/grunt/gulp/etc.

Check the Babel build system integration page. Chances are good there's already a plugin ready to use in your project.

I'm using esnext via Ember CLI.

ember-cli v0.1.7 uses Babel instead of esnext by default, so update your Ember app to use that version or later.

A note on ES6 modules.

Since esnext never handled modules, but Babel does, you may need to adjust your build pipeline. You can either start using Babel's built-in module transforms, or continue using whatever tool you were using for modules. To prevent Babel from handling modules, blacklist the modules transform.

Install

$ npm install [--save-dev] esnext

Goals

  • Allow using future JavaScript syntax today.
  • Require as little runtime code as possible.
  • Generate human-readable code.

Non-Goals

  • Provide polyfills for future JavaScript APIs.
  • Line-by-line equivalence from source to compiled.

Features

Available

TODO

Any omissions here are not intentional and we'd love to integrate support for more future JavaScript syntax (see es6features for a more complete list). See the Contributing section below. Keep in mind that, as of right now, this project is intended to support new JavaScript syntax only. Any new APIs should be handled using polyfills. This may change in the future.

Usage

As a CLI

esnext ships with a command-line interface that can be used when installed globally (or from within your project at node_modules/.bin/esnext when installed locally). Here's how to compile a single file an print it to stdout:

$ esnext myfile.js

To execute compiled code:

$ esnext -e myfile.js

If you don't care about a certain feature, such as arrow functions, you can omit support for them like so:

$ esnext --no-arrow-function myfile.js

To compile many files at once, specify an output directory:

$ esnext -o build lib/**/*.js

To enable source maps for these files, add the --source-maps flag.

As a Library

var compile = require('esnext').compile;
var result = compile(es6Source);
fs.writeFileSync('result.js', result.code, 'utf8');
fs.writeFileSync('result.js.map', JSON.stringify(result.map), 'utf8');

With other tools

esnext can be used out of the box as a Browserify transform (and can be used with watchify for better efficiency). For example:

$ browserify -t esnext main.js

Or, use one of these libraries that integrate esnext with other tools:

Contributing

Build Status

Setup

First, install the development dependencies:

$ npm install

Then, try running the tests:

$ npm test

Pull Requests

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request

Any contributors to the master esnext repository must sign the Individual Contributor License Agreement (CLA). It's a short form that covers our bases and makes sure you're eligible to contribute.

When you have a change you'd like to see in the master repository, send a pull request. Before we merge your request, we'll make sure you're in the list of people who have signed a CLA.

Acknowledgements

Huge thanks to Ben Newman for recast and regenerator. Thanks to Ariya Hidayat for esprima. Thanks also to Thomas Boyt for his work on the es6-module-transpiler, es6-class, es6-arrow-function, and others.

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