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This Ember-CLI plugin uses Babel and babel-preset-env to allow you to use ES6 syntax with your Ember CLI project.


ember install ember-cli-babel


This plugin should work without any configuration after installing. By default it will take every .js file in your project and run it through the Babel transpiler to convert your ES6 code to code supported by your target browsers (as specified in config/targets.js in ember-cli >= 2.13). Running non-ES6 code through the transpiler shouldn't change the code at all (likely just a format change if it does).

If you need to customize the way that babel-preset-env configures the plugins that transform your code, you can do it by passing in any of the options found here.

Example (configuring babel directly):

// ember-cli-build.js 
var app = new EmberApp({
  babel: {
    // enable "loose" mode 
    loose: true,
    // don't transpile generator functions 
    exclude: [

Example (configuring ember-cli-babel itself):

// ember-cli-build.js 
var app = new EmberApp({
  'ember-cli-babel': {
    compileModules: false


Babel comes with a polyfill that includes a custom regenerator runtime and core.js. Many transformations will work without it, but for full support you must include the polyfill in your app. The Babel feature tour includes a note for features that require the polyfill to work.

To include it in your app, pass includePolyfill: true in your ember-cli-babel options.

// ember-cli-build.js 
var app = new EmberApp(defaults, {
  'ember-cli-babel': {
    includePolyfill: true

Addon usage

For addons which want additional customizations, they are able to interact with this addon directly.

treeForAddon(tree) {
  let addon = this.addons.find(addon => === 'ember-cli-babel'); // find your babel addon 
  let options = addon.buildBabelOptions({
  return addon.transpileTree(tree, {
    'babel': {
      // any babel specific options 
    'ember-cli-babel': {
      // any ember-cli-babel options 

Debug Tooling

In order to allow apps and addons to easily provide good development mode ergonomics (assertions, deprecations, etc) but still perform well in production mode ember-cli-babel automatically manages stripping / removing certain debug statements. This concept was originally proposed in ember-cli/rfcs#50, but has been slightly modified during implementation (after researching what works well and what does not).

Debug Macros

To add convienient deprecations and assertions, consumers (in either an app or an addon) can do the following:

import { deprecate, assert } from '@ember/debug';
export default Ember.Component.extend({
  init() {
      'Passing a string value or the `sauce` parameter is deprecated, please pass an instance of Sauce instead',
      { until: '1.0.0', id: 'some-addon-sauce' }
    assert('You must provide sauce for x-awesome.', this.sauce);

In testing and development environments those statements will be executed (and assert or deprecate as appropriate), but in production builds they will be inert (and stripped during minification).

The following are named exports that are available from @ember/debug:

  • function deprecate(message: string, predicate: boolean, options: any): void - Results in calling Ember.deprecate.
  • function assert(message: string, predicate: boolean): void - Results in calling Ember.assert.
  • function warn(message: string, predicate: boolean) - Results in calling Ember.warn.

General Purpose Env Flags

In some cases you may have the need to do things in debug builds that isn't related to asserts/deprecations/etc. For example, you may expose certain API's for debugging only. You can do that via the DEBUG environment flag:

import { DEBUG } from '@glimmer/env';
const Component = Ember.Component.extend();
if (DEBUG) {
    specialMethodForDebugging() {
      // do things ;) 

In testing and development environments DEBUG will be replaced by the boolean literal true, and in production builds it will be replaced by false. When ran through a minifier (with dead code elimination) the entire section will be stripped.

Disabling Debug Tooling Support

If for some reason you need to disable this debug tooling, you can opt-out via configuration.

In an app that would look like:

// ember-cli-build.js 
module.exports = function(defaults) {
  let app = new EmberApp(defaults, {
    'ember-cli-babel': {
      disableDebugTooling: true
  return app.toTree();

About Modules

Older versions of Ember CLI (< 2.12) use its own ES6 module transpiler. Because of that, this plugin disables Babel module compilation by blacklisting that transform when running under affected ember-cli versions. If you find that you want to use the Babel module transform instead of the Ember CLI one, you'll have to explicitly set compileModules to true in your configuration. If compileModules is anything other than true, this plugin will leave the module syntax compilation up to Ember CLI.