node package manager



npm version build status downloads js-standard-style

The easiest way to compile JavaScript, HTML and CSS.

We want people to have fun building things for the web. There should be no hurdles between a great idea, and your first prototype. And once you're ready, it should be easy to package it up and share it online. That's Bankai: a tool that helps you build for the web. No configuration, and no hassle - that's our promise.

If this is your first time building something for the web, take a look at choojs/create-choo-app to help get a project setup from scratch ✨.


  $ bankai <command> [entry] [options]
    build       compile all files to dist/
    inspect     inspect the bundle dependencies
    start       start a development server
    -d, --debug       output lots of logs
    -h, --help        print usage
    -q, --quiet       don't output any logs
    -v, --version     print version
    Start a development server
    $ bankai start index.js
    Visualize all dependencies in your project
    $ bankai inspect index.js
    Compile all files in the project to disk
    $ bankai build index.js
  Running into trouble? Feel free to file an issue:
  Do you enjoy using this software? Become a backer:

⚠️ HTTPS Instructions

When you first open up your application in a browser, you'll probably see a warning page about HTTPS connections being untrusted. No worries, this is entirely expected behavior. Follow the instructions below to solve this for your browser.

How does this work? For HTTPS to run on localhost, we must sign a TLS certificate locally. This is better known as a "self-signed certificate". Browsers actively check for certificates from uknown providers, and warn you (for good reason!) In our case, however, it's safe to ignore.

HTTPS is needed for an increasing amount of APIs to work in the browser. For example if you want to test HTTP/2 connections or use parts of the storage API, you have no choice but to use an HTTPS connection on localhost. That's why we try and make this work as efficiently, and securely as possible.

We generate a unique certificate for each Bankai installation. This means that you'll only need to trust an HTTPS certificate for Bankai once. This should be secure from remote attackers, because unless they have successfully acquired access to your machine's filesystem, they won't be able to replicate the certificate.

Firefox Instructions

Step 1

A wild security screen appears!. Click on "advanced". firefox01

Step 2

More details emerge! Click on "Add Exception". firefox02

Step 3

In the dropdown click "Confirm Security Exception". firefox03

Step 4

Success! firefox04

Chrome Instructions Click the "more details" dropdown, then click "proceed". Pull Request for screenshots welcome!
Safari Instructions

Step 1

A wild security screen appears! Click "Show Certificate". safari01

Step 2

More details emerge! Check "Always trust 'localhost'…". safari02

Step 3

The box is checked! Click "Continue". safari03

Step 4

A box is asking you for your crendentials. Fill them in, and hit "Enter".

Step 5

Success! safari04


Bankai applies lots of optimizations to projects. Generally you won't need to care how we do this: it's lots of glue code, and not necessarily pretty. But it can be useful to know which optimizations we apply. This is a list:


  • bundle-collapser: Remove all pathnames from inside the bundle, and replace them with IDs. This not only makes bundles smaller, it prevents details from your local dev setup leaking.
  • common-shakeify: Remove unused JavaScript code from the bundle. Best known as dead code elimination or tree shaking.
  • unassertify: Remove all require('assert') statements from the code. Only applied for production builds.
  • uglifyify: Minify the bundle.
  • yo-yoify: Optimize choo HTML code so it run significantly faster in the browser.
  • glslify: Adds a module system to GLSL shaders.
  • envify: Allow environment variables to be used in the bundle. Especially useful in combination with minification, which removes unused code paths.
  • brfs: Statically inline calls to fs.readFile(). Useful to ship assets in the browser.
  • split-require: Lazy load parts of your application using the require('split-require') function.
  • babelify: Bring the latest browser features to all browsers. See our babel section for more details.


  • sheetify: extract all inline CSS from JavaScript, and include it in bundle.js.
  • purifyCSS: removes unused CSS from the project.
  • cleanCSS: minify the bundle.


  • inline-critical-css: extract all crititical CSS for a page into the <head> of the document. This means that every page will be able to render after the first roundtrip, which makes for super snappy pages.
  • async load scripts: loads scripts in the background using the defer attribute.
  • async load styles: loads styles in the background using the preload attribute.
  • async load styles: preloads fonts in the background using the preload attribute.
  • server render: server renders Choo applications. We're welcome to supporting other frameworks too. PRs welcome!
  • manifest: includes a link to manifest.json so the application can be installed on mobile.
  • viewport: defines the right viewport dimensions to make applications accessible for everyone.
  • theme color: sets the theme color defined in manifest.json so the navigator bar on mobile is styled on brand.
  • title: sets the right title on a page. Either extracts it from the application (choo only, for now) or uses whatever the title is in manifest.json.
  • live reload: during development, we inject a live reload script.


The Bankai CLI doesn't take any flags, other than to manipulate how we log to the console. Configuring Bankai is done by modifying package.json.

Bankai is built on three technologies: browserify, sheetify, and documentify. Because these can be configured inside package.json it means that Bankai itself can be configured from there too. Also if people ever decide to switch from the command line to JavaScript, no extra configuration is needed.

  "name": "my-app",
  "browserify": {
     "transform": [
   "sheetify": {
     "transform": [
   "documentify": {
     "transform": [


Bankai can be hooked up directly to an HTTP server, which is useful when working on full stack code.

var bankai = require('bankai/http')
var http = require('http')
var path = require('path')
var compiler = bankai(path.join(__dirname, 'client.js'))
var server = http.createServer(function (req, res) {
  compiler(req, res, function () {
    res.statusCode = 404
    res.end('not found')
server.listen(8080, function () {
  console.log('listening on port 8080')


Not all browsers support all of the Web Platform's features. So in order to use newer features on older browsers, we have to find a solution. The best solution out there at the moment is Babel.

Babel is a plugin-based JavaScript compiler. It takes JavaScript in, and outputs JavaScript based for the platforms you've decided to target. In Bankai we target the last 2 versions of FireFox, Chrome and Edge, and every other browser that's used by more than 1% of people on earth. This includes IE11. And if you have different opinions on which browsers to use, Bankai respects .babelrc files.

Some newer JavaScript features require loading an extra library; async/await being the clearest example. To enable this features, the babel-polyfill library needs to be included in your application's root (e.g. index.js).


We don't include this file by default in Bankai, because it has a significant size overhead. Once Babel includes only the language features you're using, we'll work to include babel-polyfill by default.


compiler.on('error', callback(nodeName, edgeName, error))

Whenever an internal error occurs.

compiler.on('change', callback(nodeName, edgeName, state))

Whenever a change in the internal graph occurs.


compiler = bankai(entry, [opts])

Create a new bankai instance. Takes a path to a JavaScript file as the first argument. The following options are available:

  • opts.quiet: Defaults to false. Don't output any data to stdout. Useful if you have your own logging system.
  • Defaults to true. Watch for changes in the source files and rebuild. Set to false to get optimized bundles.

compiler.documents(routename, [opts], done(err, { buffer, hash }))

Output an HTML bundle for a route. Routes are determined based on the project's router. Pass '/' to get the default route.

  • opts.state: Will be passed the render function for the route, and inlined in the <head> of the body as window.initialState.

compiler.scripts(filename, done(err, { buffer, hash }))

Pass in a filename and output a JS bundle.

compiler.assets(assetName, done(err, { buffer, hash }))

Output any other file besides JS, CSS or HTML.

compiler.styles(name, done(err, { buffer, hash }))

Output a CSS bundle.

compiler.manifest(done(err, { buffer, hash }))

Output a manifest.json.

compiler.serviceWorker(done(err, { buffer, hash }))

Output a service worker.


Close all file watchers.


Apache License 2.0