ember-cli-babel

This Ember-CLI plugin uses Babel and @babel/preset-env to allow you to use latest Javascript in your Ember CLI project.

Table of Contents

• Installation
• Compatibility
• Usage
  • Options
    • Polyfill
    • External Helpers
    • Enabling Source Maps
    • Modules
    • Disabling Debug Tooling Support
    • Enabling TypeScript Transpilation
  • Addon usage
    • Adding Custom Plugins
    • Additional Trees
    • buildBabelOptions usage
    • transpileTree usage
  • Debug Tooling
    • Debug Macros
    • General Purpose Env Flags
    • Parallel Builds

Installation

ember install ember-cli-babel

Compatibility

• ember-cli-babel 7.x requires ember-cli 2.13 or above

Usage

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 babel/babel-preset-env options. Note: .babelrc files are ignored by default.

Example (configuring babel directly):

// ember-cli-build.js
 
let app = new EmberApp({
  babel: {
    // enable "loose" mode
    loose: true,
    // don't transpile generator functions
    exclude: [
      'transform-regenerator',
    ],
    plugins: [
      require.resolve('transform-object-rest-spread')
    ]
  }
});

Example (configuring ember-cli-babel itself):

// ember-cli-build.js
 
let app = new EmberApp({
  'ember-cli-babel': {
    compileModules: false
  }
});

Options

There are a few different options that may be provided to ember-cli-babel. These options are typically set in an apps ember-cli-build.js file, or in an addon or engine's index.js.

type BabelPlugin = string | [string, any] | [any, any];
 
interface EmberCLIBabelConfig {
  /**
    Configuration options for babel-preset-env.
    See https://github.com/babel/babel-preset-env/tree/v1.6.1#options for details on these options.
  */
  babel?: {
    spec?: boolean;
    loose?: boolean;
    debug?: boolean;
    include?: string[];
    exclude?: string[];
    useBuiltIns?: boolean;
    sourceMaps?: boolean | "inline" | "both";
    plugins?: BabelPlugin[];
  };
 
  /**
    Configuration options for ember-cli-babel itself.
  */
  'ember-cli-babel'?: {
    includePolyfill?: boolean;
    includeExternalHelpers?: boolean;
    compileModules?: boolean;
    disableDebugTooling?: boolean;
    disablePresetEnv?: boolean;
    disableEmberModulesAPIPolyfill?: boolean;
    disableEmberDataPackagesPolyfill?: boolean;
    disableDecoratorTransforms?: boolean;
    enableTypeScriptTransform?: boolean;
    extensions?: string[];
  };
}

The exact location you specify these options varies depending on the type of project you're working on. As a concrete example, to add babel-plugin-transform-object-rest-spread so that your project can use object rest/spread syntax, you would do something like this in an app:

// ember-cli-build.js
let app = new EmberApp(defaults, {
  babel: {
    plugins: [require.resolve('transform-object-rest-spread')]
  }
});

In an engine:

// index.js
module.exports = EngineAddon.extend({
  babel: {
    plugins: [require.resolve('transform-object-rest-spread')]
  }
});

In an addon:

// index.js
module.exports = {
  options: {
    babel: {
      plugins: [require.resolve('transform-object-rest-spread')]
    }
  }
};

Polyfill

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 may need to include the polyfill in your app.

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

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

External Helpers

Babel often includes helper functions to handle some of the more complex logic in codemods. These functions are inlined by default, so they are duplicated in every file that they are used in, which adds some extra weight to final builds.

Enabling includeExternalHelpers will cause Babel to import these helpers from a shared module, reducing app size overall. This option is available only to the root application, because it is a global configuration value due to the fact that there can only be one version of helpers included.

Note that there is currently no way to allow or ignore helpers, so all helpers will be included, even ones which are not used. If your app is small, this could add to overall build size, so be sure to check.

ember-cli-babel will attempt to include helpers if it believes that it will lower your build size, using a number of heuristics. You can override this to force inclusion or exclusion of helpers in your app by passing true or false to includeExternalHelpers in your ember-cli-babel options.

// ember-cli-build.js
 
let app = new EmberApp(defaults, {
  'ember-cli-babel': {
    includeExternalHelpers: true
  }
});

Enabling Source Maps

Babel generated source maps will enable you to debug your original ES6 source code. This is disabled by default because it will slow down compilation times.

To enable it, pass sourceMaps: 'inline' in your babel options.

// ember-cli-build.js
 
let app = new EmberApp(defaults, {
  babel: {
    sourceMaps: 'inline'
  }
});

Modules

Older versions of Ember CLI (< 2.12) use its own ES6 module transpiler. Because of that, this plugin disables Babel module compilation by ignoring 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.

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();
}

Enabling TypeScript Transpilation

The transform plugin required for Babel to transpile TypeScript will automatically be enabled when ember-cli-typescript >= 4.0 is installed.

You can enable the TypeScript Babel transform manually without ember-cli-typescript by setting the enableTypeScriptTransform to true.

NOTE: Setting this option to true is not compatible with ember-cli-typescript < 4.0 because of conflicting Babel plugin ordering constraints and is unnecessary because ember-cli-typescript < 4.0 adds the TypeScript Babel transform itself.

NOTE: Setting this option to true does not enable type-checking. For integrated type-checking, you will need ember-cli-typescript.

In an app, manually enabling the TypeScript transform would look like:

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

Addon usage

Adding Custom Plugins

You can add custom plugins to be used during transpilation of the addon/ or addon-test-support/ trees by ensuring that your addon's options.babel is properly populated (as mentioned above in the Options section).

Additional Trees

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

interface EmberCLIBabel {
  /**
    Used to generate the options that will ultimately be passed to babel itself.
  */
  buildBabelOptions(config?: EmberCLIBabelConfig): Opaque;
 
  /**
    Supports easier transpilation of non-standard input paths (e.g. to transpile
    a non-addon NPM dependency) while still leveraging the logic within
    ember-cli-babel for transpiling (e.g. targets, preset-env config, etc).
  */
  transpileTree(inputTree: BroccoliTree, config?: EmberCLIBabelConfig): BroccoliTree;
 
  /**
    Used to determine if a given plugin is required by the current target configuration.
    Does not take `includes` / `excludes` into account.
 
    See https://github.com/babel/babel-preset-env/blob/master/data/plugins.json for the list
    of known plugins.
  */
  isPluginRequired(pluginName: string): boolean;
}

buildBabelOptions usage

// find your babel addon (can use `this.findAddonByName('ember-cli-babel')` in ember-cli@2.14 and newer)
let babelAddon = this.addons.find(addon => addon.name === 'ember-cli-babel');
 
// create the babel options to use elsewhere based on the config above
let options = babelAddon.buildBabelOptions(config)
 
// now you can pass these options off to babel or broccoli-babel-transpiler
require('babel-core').transform('something', options);

transpileTree usage

// find your babel addon (can use `this.findAddonByName('ember-cli-babel')` in ember-cli@2.14 and newer)
let babelAddon = this.addons.find(addon => addon.name === 'ember-cli-babel');
 
// invoke .transpileTree passing in the custom input tree
let transpiledCustomTree = babelAddon.transpileTree(someCustomTree);

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() {
    this._super(...arguments);
    deprecate(
      'Passing a string value or the `sauce` parameter is deprecated, please pass an instance of Sauce instead',
      false,
      { 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): void - 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) {
  Component.reopen({
    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.

Please note, that these general purpose environment related flags (e.g. DEBUG as a boolean flag) are imported from @glimmer/env not from an @ember namespace.

Parallel Builds

By default, broccoli-babel-transpiler will attempt to spin up several sub-processes (~1 per available core), to achieve parallelization. (Once Node.js has built-in worker support, we plan to utilize it.) This yields significant Babel build time improvements.

Unfortunately, some Babel plugins may break this functionality. When this occurs, we gracefully fallback to the old serial strategy.

To have the build fail when failing to do parallel builds, opt-in is via:

let app = new EmberAddon(defaults, {
  'ember-cli-babel': {
    throwUnlessParallelizable: true
  }
});

Note: Future versions will enable this flag by default.

Read more about broccoli parallel transpilation.