Broccoli plugin for Babel
JavaScript
Latest commit 647aa9c Jan 5, 2017 @rwjblue rwjblue 6.0.0-alpha.3

README.md

broccoli-babel-transpiler

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A Broccoli plugin which transpiles ES6 to readable ES5 by using babel.

How to install?

$ npm install broccoli-babel-transpiler --save-dev

How to use?

In your Brocfile.js:

var esTranspiler = require('broccoli-babel-transpiler');
var scriptTree = esTranspiler(inputTree, options);

You can find options at babel's github repo.

Examples

You'll find three example projects using this plugin in the repository broccoli-babel-examples. Each one of them builds on top of the previous example so you can progess from bare minimum to ambitious development.

About source map

Currently this plugin only supports inline source map. If you need separate source map feature, you're welcome to submit a pull request.

Advanced usage

filterExtensions is an option to limit (or expand) the set of file extensions that will be transformed.

The default filterExtension is js

var esTranspiler = require('broccoli-babel-transpiler');
var scriptTree = esTranspiler(inputTree, {
    filterExtensions:['js', 'es6'] // babelize both .js and .es6 files
});

Polyfill

In order to use some of the ES6 features you must include the Babel polyfill.

You don't always need this, review which features need the polyfill here: ES6 Features.

var esTranspiler = require('broccoli-babel-transpiler');
var scriptTree = esTranspiler(inputTree, { browserPolyfill: true });

Plugins

Use of custom plugins works similarly to babel itself. You would pass a plugins array in options:

var esTranspiler = require('broccoli-babel-transpiler');
var applyFeatureFlags = require('babel-plugin-feature-flags');

var featureFlagPlugin = applyFeatureFlags({
  import: { module: 'ember-metal/features' },
  features: {
    'ember-metal-blah': true
  }
});

var scriptTree = esTranspiler(inputTree, {
  plugins: [
    featureFlagPlugin
  ]
});

Caching

broccoli-babel-transpiler uses a persistent cache to enable rebuilds to be significantly faster (by avoiding transpilation for files that have not changed). However, since a plugin can do many things to affect the transpiled output it must also influence the cache key to ensure transpiled files are rebuilt if the plugin changes (or the plugins configuration).

In order to aid plugin developers in this process, broccoli-babel-transpiler will invoke two methods on a plugin so that it can augment the cache key:

  • cacheKey - This method is used to describe any runtime information that may want to invalidate the cached result of each file transpilation. This is generally only needed when the configuration provided to the plugin is used to modify the AST output by a plugin like babel-plugin-filter-imports (module exports to strip from a build), babel-plugin-feature-flags (configured features and current status to strip or embed in a final build), or babel-plugin-htmlbars-inline-precompile (uses ember-template-compiler.js to compile inlined templates).
  • baseDir - This method is expected to return the plugins base dir. The provided baseDir is used to ensure the cache is invalidated if any of the plugin's files change (including its deps). Each plugin should implement baseDir as: Plugin.prototype.baseDir = function() { return \_\_dirname; };.