browser-side require() the node.js way
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require('modules') in the browser

Use a node-style require() to organize your browser code and load modules installed by npm.

browserify will recursively analyze all the require() calls in your app in order to build a bundle you can serve up to the browser in a single <script> tag.

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Whip up a file, main.js with some require()s in it. You can use relative paths like './foo' and '../lib/bar' or module paths like 'gamma' that will search node_modules/ using node's module lookup algorithm.

var foo = require('./foo');
var bar = require('../lib/bar');
var gamma = require('gamma');

var elem = document.getElementById('result');
var x = foo(100) + bar('baz');
elem.textContent = gamma(x);

Now just use the browserify command to build a bundle starting at main.js:

$ browserify main.js > bundle.js

All of the modules that entry.js needs are included in the bundle.js from a recursive walk of the require() graph using required.

To use this bundle, just toss a <script src="bundle.js"></script> into your html!

external requires

You can just as easily create bundle that will export a require() function so you can require() modules from another script tag. Here we'll create a bundle.js with the through and duplexer modules.

$ browserify -r through -r duplexer > bundle.js

Then in your page you can do:

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

multiple bundles

If browserify finds a require function already defined in the page scope, it will fall back to that function if it didn't find any matches in its own set of bundled modules.

In this way you can use browserify to split up bundles among multiple pages to get the benefit of caching for shared, infrequently-changing modules, while still being able to use require(). Just use a combination of --external and --require to factor out common dependencies.

For example, if a website with 2 pages, beep.js:

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

and boop.js:

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

both depend on robot.js:

module.exports = function (s) { return s.toUpperCase() + '!' };
$ browserify -r ./robot > static/common.js
$ browserify -x ./robot.js beep.js > static/beep.js
$ browserify -x ./robot.js boop.js > static/boop.js

Then on the beep page you can have:

<script src="common.js"></script>
<script src="beep.js"></script>

while the boop page can have:

<script src="common.js"></script>
<script src="boop.js"></script>


Usage: browserify [entry files] {OPTIONS}

Standard 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   Omit a file from the output bundle.

  --external, -x Reference a file from another bundle.

  --help, -h     Show this message

Advanced Options:

  --insert-globals, --ig, --fast    [default: false]

    Skip detection and always insert definitions for process, global,
    __filename, and __dirname.

    benefit: faster builds
    cost: extra bytes

  --detect-globals, --dg            [default: true]

    Detect the presence of process, global, __filename, and __dirname and define
    these values when present.

    benefit: npm modules more likely to work
    cost: slower builds

  --ignore-missing, --im            [default: false]

    Ignore `require()` statements that don't resolve to anything.

Specify a parameter.


Many npm modules that don't do IO will just work after being browserified. Others take more work.

Many node built-in modules have been wrapped to work in the browser, but only when you explicitly require() or use their functionality.

When you require() any of these modules, you will get a browser-specific shim:

  • events
  • stream
  • path
  • assert
  • url
  • util
  • querystring
  • buffer
  • buffer_ieee754
  • console
  • vm
  • http
  • crypto
  • zlib

Additionally if you use any of these variables, they will be defined in the bundled output in a browser-appropriate way:

  • process
  • global - top-level scope object (window)
  • __filename - file path of the currently executing file
  • __dirname - directory path of the currently executing file


var browserify = require('browserify')

var b = browserify(files=[])

Create a browserify instance b from the entry main files. files can be an array of files or a single file.


Add an entry file from file that will be executed when the bundle loads.


Make name available from outside the bundle with require(name).

The package name is anything that can be resolved by require.resolve().

b.bundle(opts, cb)

Bundle the files and their dependencies into a single javascript file.

Return a readable stream with the javascript file contents or optionally specify a cb(err, src) to get the buffered results.

When opts.insertGlobals is true, always insert process, global, __filename, and __dirname without analyzing the AST for faster builds but larger output bundles. Default false.

When opts.detectGlobals is true, scan all files for process, global, __filename, and __dirname, defining as necessary. With this option npm modules are more likely to work but bundling takes longer. Default true.


Prevent file from being loaded into the current bundle, instead referencing from another bundle.


Prevent the module name or file at file from showing up in the output bundle.


browserify uses the package.json in its module resolution algorithm just like node, but there is a special "browsers" field you can set to override file resolution for browser-specific versions.


With npm do:

npm install -g browserify