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2.3.0 • Public • Published


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A fast, reliable asset pipeline, supporting constant-time rebuilds and compact build definitions. Comparable to the Rails asset pipeline in scope, though it runs on Node and is backend-agnostic. For background and architecture, see the introductory blog post.

For the command line interface, see broccoli-cli.


npm install --save-dev broccoli
npm install --global broccoli-cli


A Brocfile.js file in the project root contains the build specification. It should export a function that returns a tree. Note: the Brocfile historically could export a tree/string directly, however this is now deprecated in favor of a function that can receive options

A tree can be any string representing a directory path, like 'app' or 'src'. Or a tree can be an object conforming to the Plugin API Specification. A Brocfile.js will usually directly work with only directory paths, and then use the plugins in the Plugins section to generate transformed trees.

The following simple Brocfile.js would export the app/ subdirectory as a tree:

export default () => 'app';

With that Brocfile, the build result would equal the contents of the app tree in your project folder. For example, say your project contains these files:

├─ main.js
└─ helper.js

Running broccoli build the-output (a command provided by broccoli-cli) would generate the following folder within your project folder:

├─ main.js
└─ helper.js


The function that is exported from module.exports is passed an options hash by Broccoli that can be used when assembling the build.

The options hash is populated by the CLI environment when running broccoli build or broccoli serve. It currently only accepts a single option --environment, which is passed as env in the options hash.

Additionally --prod and --dev are available aliases to --environment=production and --environment=development respectively.

  • options:
    • env: Defaults to development, and can be overridden with the CLI argument --environment=X

For example:

export default (options) => {
    // tree = ... assemble tree
    // In production environment, minify the files
    if (options.env === 'production') {
        tree = minify(tree);
    return tree;

TypeScript Support

A Brocfile.ts can be used in place of a Brocfile.js and Broccoli will automatically parse this through ts-node to provide TypeScript support. This allows developers to leverage type information when assembling a build pipeline. By default, Broccoli provides type information for the options object passed to the build function.

import { BrocfileOptions } from 'broccoli';
export default (options: BrocfileOptions) => {
  // tree = ... assemble tree
  // In production environment, minify the files
  if (options.env === 'production') {
    tree = minify(tree);
  return tree;

Typescript by default only allows the ES6 modules import/export syntax to work when importing ES6 modules. In order to import a CommonJS module (one that uses require() or module.exports, you must use the following syntax:

import foo = require('foo');
export = 'bar';

You'll note the syntax is slightly different from the ESM syntax, but reads fairly well.

Using plugins in a Brocfile.js

The following Brocfile.js exports the app/ subdirectory as appkit/:

// Brocfile.js
import Funnel from 'broccoli-funnel';
export default () => new Funnel('app', {
  destDir: 'appkit'

Broccoli supports ES6 modules via esm for Brocfile.js. Note, TypeScript requires the use of a different syntax, see the TypeScript section above.

You can also use regular CommonJS require and module.exports if you prefer, however ESM is the future of Node, and the recommended syntax to use.

That example uses the plugin broccoli-funnel. In order for the import call to work, you must first put the plugin in your devDependencies and install it, with

npm install --save-dev broccoli-funnel

With the above Brocfile.js and the file tree from the previous example, running broccoli build the-output would generate the following folder:

└─ appkit
   ├─ main.js
   └─ helper.js


You can find plugins under the broccoli-plugin keyword on npm.

Using Broccoli Programmatically

In addition to using Broccoli via the combination of broccoli-cli and a Brocfile.js, you can also use Broccoli programmatically to construct your own build output via the Builder class. The Builder is one of the core APIs in Broccoli, and is responsible for taking a graph of Broccoli nodes and producing an actual build artifact (i.e. the output usually found in your dist directory after you run broccoli build). The output of a Builder's build method is a Promise that resolves when all the operations in the graph are complete. You can use this promise to chain together additional operations (such as error handling or cleanup) that will execute once the build step is complete.

By way of example, let's assume we have a graph of Broccoli nodes constructed via a combination of Funnel and MergeTrees:

// non Brocfile.js, regular commonjs
const Funnel = require('broccoli-funnel');
const Merge = require('broccoli-merge');
const html = new Funnel(appRoot, {
  files: ['index.html'],
  annotation: 'Index file'
const js = new Funnel(appRoot, {
  files: ['app.js'],
  destDir: '/assets',
  annotation: 'JS Files'
const css = new Funnel(appRoot, {
  srcDir: 'styles',
  files: ['app.css'],
  destDir: '/assets',
  annotation: 'CSS Files'
const public = new Funnel(appRoot, {
  annotation: 'Public Files'
const tree = new Merge([html, js, css, public]);

At this point, tree is a graph of nodes, each of which can represent either an input or a transformation that we want to perform. In other words, tree is an abstract set of operations, not a concrete set of output files.

In order to perform all the operations described in tree, we need to do the following:

  • construct a Builder instance, passing in the graph we constructed before
  • call the build method, which will traverse the graph, performing each operation and eventually writing the output to a temporary folder indicated by builder.outputPath

Since we typically want do more than write to a temporary folder, we'll also use a library called TreeSync to sync the contents of the temp file with our desired output directory. Finally, we'll clean up the temporary folder once all our operations are complete:

const { Builder } = require('broccoli');
const TreeSync = require('tree-sync');
const Merge = require('broccoli-merge');
// ...snip...
const tree = new Merge([html, js, css, public]);
const builder = new Builder(tree);
const outputDir = 'dist';
const outputTree = new TreeSync(builder.outputPath, outputDir);
  .then(() => {
    // Calling `sync` will synchronize the contents of the builder's `outPath` with our output directory.
    return outputTree.sync();
  .then(() => {
    // Now that we're done with the build, clean up any temporary files were created
    return builder.cleanup();
  .catch(err => {
    // In case something in this process fails, we still want to ensure that we clean up the temp files
    return builder.cleanup();

Running Broccoli, Directly or Through Other Tools


Shared code for writing plugins.

Plugin API Specification

See docs/

Also see docs/ on how to upgrade from Broccoli 0.x to the Broccoli 1.x API.


  • Do not run broccoli serve on a production server. While this is theoretically safe, it exposes a needlessly large amount of attack surface just for serving static assets. Instead, use broccoli build to precompile your assets, and serve the static files from a web server of your choice.

Get Help

  • IRC: #broccolijs on Freenode. Ask your question and stick around for a few hours. Someone will see your message eventually.
  • Twitter: mention @jo_liss with your question
  • GitHub: Open an issue on a specific plugin repository, or on this repository for general questions.


Broccoli was originally written by Jo Liss and is licensed under the MIT license.

The Broccoli logo was created by Samantha Penner (Miric) and is licensed under CC0 1.0.


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