browser-side require() the node.js way
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Make node-style require() work in the browser, as if by magic!

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Browserify generates a single static bundle that you can drop into your application with a single <script> tag. You can use browserify with any kind of web stack that can host up static files.


Just write an entry.js to start with some require()s in it:

var foo = require('./foo');

window.onload = function () {
    document.getElementById('result').innerHTML = foo(100);

and then a foo.js:

var bar = require('./bar');

module.exports = function (x) {
    return x * bar.coeff(x) + (x * 3 - 2)

and then a bar.js:

exports.coeff = function (x) {
    return Math.log(x) / Math.log(2) + 1;

Now you need to build this. You can either:

  1. use the browserify CLI tool
  2. use the middleware
  3. use the API

using the CLI tool

browserify entry.js -o browserify.js

Then just throw a <script src="/browserify.js"></script> into your HTML!

using the middleware

var express = require('express');
var app = express.createServer();

var bundle = require('browserify')(__dirname + '/entry.js');

Then just throw a <script src="/browserify.js"></script> into your HTML!

using the API

See below.

features at a glance

  • use npm modules in the browser

  • require()s work browser-side just as they do in node

  • coffee script just works™ — just require('./') or whichever

  • lots of node builtins just work™:

    • require('events')
    • require('path')
    • require('vm')
    • require('http')
    • require('assert')
    • require('url')
    • require('buffer')
    • require('util')
    • require('querystring')
  • lots of ways to compile

  • watch mode automatically recompiles your bundle when files change

  • debug mode for real line numbers (just subtract 2)

command-line usage

Usage: node ./bin/cli.js [entry files] {OPTIONS}

  --outfile, -o  Write the browserify bundle to this file.
                 If unspecified, browserify prints to stdout.                   
  --require, -r  A module name or file to bundle.require()
                 Optionally use a colon separator to set the target.            
  --entry, -e    An entry point of your app                                     
  --ignore, -i   Ignore a file                                                  
  --alias, -a    Register an alias with a colon separator: "to:from"
                 Example: --alias 'jquery:jquery-browserify'                    
  --cache, -c    Turn on caching at $HOME/.config/browserling/cache.json or use
                 a file for caching.
                                                                 [default: true]
  --debug, -d    Switch on debugging mode with //@ sourceURL=...s.     [boolean]
  --plugin, -p   Use a plugin. Use a colon separator to specify additional
                 plugin arguments as a JSON string.
                 Example: --plugin 'fileify:["files","."]'                      
  --prelude      Include the code that defines require() in this bundle.
                                                      [boolean]  [default: true]
  --watch, -w    Watch for changes. The script will stay open and write updates
                 to the output every time any of the bundled files change.
                 This option only works in tandem with -o.                      
  --verbose, -v  Write out how many bytes were written in -o mode. This is
                 especially useful with --watch.                                
  --help, -h     Show this message                                              


var browserify = require('browserify');

var b = browserify(opts={})

Return a middleware with attached methods that will host up a browserified script at opts.mount or "/browserify.js" if unspecified.

opts may also contain these fields:

  • require - calls b.require()
  • ignore - calls b.ignore()
  • entry - calls b.addEntry()
  • filter - registers a "post" extension using b.register()
  • watch - set watches on files, see below
  • cache - turn on caching for AST traversals, see below
  • debug - turn on source mapping for debugging with //@ sourceURL=... in browsers that support it

If opts is a string, it is interpreted as a require value.

Any query string after opts.mount will be ignored.

watch :: Boolean or Object

Set watches on files and automatically rebundle when a file changes.

This option defaults to false. If is set to true, default watch arguments are assumed or you can pass in an object to pass along as the second parameter to fs.watchFile().

cache :: Boolean or String

If cache is a boolean, turn on caching at $HOME/.config/browserify/cache.json.

If cache is a string, turn on caching at the filename specified by cache.

bundle events

b bundles will also emit events.

'syntaxError', err

This event gets emitted when there is a syntax error somewhere in the build process. If you don't listen for this event, the error will be printed to stderr.


In watch mode, this event is emitted when a new bundle has been generated.


Return the bundled source as a string.


Require a file or files for inclusion in the bundle.

If file is an array, require each element in it.

If file is a non-array object, map an alias to a package name. For instance to be able to map require('jquery') to the jquery-browserify package, you can do:

b.require({ jquery : 'jquery-browserify' })

and the same thing in middleware-form:

browserify({ require : { jquery : 'jquery-browserify' } })

To mix alias objects with regular requires you could do:

browserify({ require : [ 'seq', { jquery : 'jquery-browserify' }, 'traverse' ])

In practice you won't need to b.require() very many files since all the require()s are read from each file that you require and automatically included.


Omit a file or files from being included by the AST walk to hunt down require() statements.


Append a file to the end of the bundle and execute it without having to require() it.

Specifying an entry point will let you require() other modules without having to load the entry point in a <script> tag yourself.

If entry is an Array, concatenate these files together and append to the end of the bundle.


Transform the source using the filter function fn(src). The return value of fn should be the new source.

b.register(ext, fn)

Register a handler to wrap extensions.

Wrap every file matching the extension ext with the function fn.

For every file included into the bundle fn gets called for matching file types as, body, file) for the bundle instance b and the file content string body. fn should return the new wrapped contents.

If ext is unspecified, execute the wrapper for every file.

If ext is 'post', execute the wrapper on the entire bundle.

If ext is 'pre', call the wrapper function with the bundle object before the source is generated.

If ext is an object, pull the extension from ext.extension and the wrapper function fn from ext.wrapper. This makes it easy to write plugins like fileify.

Coffee script support is just implemented internally as a .register() extension:

b.register('.coffee', function (body) {
    return coffee.compile(body);


Use a middleware plugin, fn. fn is called with the instance object b.


Prepend unwrapped content to the beginning of the bundle.


Append unwrapped content to the end of the bundle.

b.alias(to, from)

Alias a package name from another package name.


Contains a Date object with the time the bundle was last modified. This field is useful in conjunction with the watch field described in the browserify() to generate unique <script> src values to force script reloading.


In order to resolve main files for projects, the package.json "main" field is read.

If a package.json has a "browserify" field, you can override the standard "main" behavior with something special just for browsers.

The "browserify" field can be a string that points to the browser-specific "main" file or it can be an object with a "main" field in it.



Browserify exports a faux process object with these attributes:

  • nextTick(fn) - uses the postMessage trick for a faster setTimeout(fn, 0) if it can
  • title - set to 'browser' for browser code, 'node' in regular node code








All the goodness of node's require('vm') has been emulated with iframe trickery. This functionality is made available by the vm-browserify project.


Implement the client side of the node http api using the http-browserify project.


The posix functions from the path module have been included except for exists() and existsSync(). Just require('path')!


The faux directory name, scrubbed of true directory information so as not to expose your filesystem organization.


The faux file path, scrubbed of true path information so as not to expose your filesystem organization.


use an npm module in the browser

First install a module:

npm install traverse

Then write an entry.js:

var traverse = require('traverse');
var obj = traverse({ a : 3, b : [ 4, 5 ] }).map(function (x) {
    if (typeof x === 'number') this.update(x * 100)

then build it!

browserify entry.js -o bundle.js

then put it in your html

<script src="bundle.js"></script>

and the entry.js will just run and require('traverse') will just work™.

convert a node module into a browser require-able standalone file

Using npm >= 1.0 from the commandz line: Install the traverse package locally (into the node_modules folder)

npm install traverse

Utilize browserify to... browserify the package

npm install -g browserify
browserify --require traverse -o bundle.js

Look at the files! There is a new one: bundle.js. Now go into HTML land:

<script src="bundle.js"></script>
   var traverse = require('traverse');

read more

browserify: browser-side require() for your node.js

ad-hoc browserify CDN!



Using npm just do:

npm install browserify

to install into your project's node_modules directory, or if you want to use the command-line tool, install globally with:

npm install -g browserify


To run the node tests with tap, do:

npm test

To run the testling tests, create a browserling account then:

cd testling