The easiest way to require NPM and CommonJS modules from your browser
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The easiest way to require and use CommonJS and NPM modules from your browser

Npm makes it easy to share code on your server. But how many times have you wanted to share Javascript code easily between the server and the browser? browser-require allows you to easily use CommonJS and NPM modules defined on the server in your browser.

browser-require enables you to require both relative (local to your project) CommonJS modules as well as global NPM modules.


To install: $ npm install browser-require

Using browser-require within your connect app

Currently, browser-require depends on the connect middleware framework, if you want to serve client javascript files that contain requires.

First, add in the browser-require middleware into your connect server: var connect = require('connect') , app = connect.createServer() , exposeRequire = require('browser-require');

// The following line "app.use(..." is what you want to add to your project
// Make sure the browser-require middleware comes before staticProvider middleware
  base: __dirname   // This is where we look to find your non-global modules


On the browser, this is what your index.html might look like:

<!DOCTYPE html>
    <title>browser-require example</title>
    <script type="text/javascript" src="/js/app.js"></script>

The script src "/js/app.js" is where your custom JavaScript code resides.

Then in /js/app.js, you can require CommonJS and NPM modules as if you are on the server:

var _ = require('underscore'); // browser-side requires FTW!!!!

// This should alert "10"
alert(_.reduce([1, 2, 3, 4], function (sum, num) {
  sum += num;
  return sum;

How it works

When you request a javascript file:

  1. The server looks up the source and its module dependencies (if any) recursively.
  2. Once the server has collected all dependencies, it compiles the top-level file plus its dependencies into a file that gets sent back to the browser.

Command line binary

Sometimes you need to statically compile a set of javascript client files from the command line. For example, this is necessary if you are building a Chrome plugin. A Chrome plugin can use JavaScript files that exist inside the Chrome plugin (as opposed to fetching a JavaScript file that exists on the server). Therefore, it is necessary in this case to compile your JavaScript files and their dependencies outside of the context of a server.

browser-require supports this via a command line binary. You can use it in the following way:

$ browser-require path/to/js/file.js > path/to/compiled/js/file.js


There are examples in the ./examples directory.

To run the relative modules example:

$ cd examples/relative
$ node server.js

To run the npm modules example:

$ npm install underscore
$ npm install data-structures-js
$ npm install validator
$ cd examples/npm
$ node server.js

Running the tests

First, make sure the following npm modules are installed, since we will be using them to test browser-require:

$ npm install underscore
$ npm install data-structures-js
$ npm install validator

First, start up the test server:

$ make start-test-server

To run tests in Chrome:

$ make test-chrome

To run tests in Firefox:

$ make test-firefox

Finally, stop the test server:

$ make stop-test-server

Planning on implementing

  • A middleware filter mechanism to include things such as a Google Closure Compiler filter.



MIT License


Brian Noguchi