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

Getting started

To install: $ npm install browser-require

Currently, browser-require depends on the connect middleware framework.

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> browser-require example <!-- This is a boilerplate file that you must require -->

    <!-- This is where your custom JavaScript code resides. See README section below -->
    <script type="text/javascript" src="/js/app.js"></script>

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

Currently, all requires from the browser load JavaScript source and dependencies from the server in a dynamic, piece-wise, and on-demand fashion.

When you request a javascript file:

  1. The server looks up the source and its module dependencies, if any.
  2. The server sends back the stringified source (SSRC) and its dependencies.
  3. If there are dependencies, then for each dependency, repeat from step 1.
  4. Once each javascript file has loaded all its dependencies, then eval and load the SSRC for the file.

The above methodology is great for development environments, where you do not constantly want to re-compile a javascript file and its dependencies into a single static JavaScript file.

That said, I will be adding static compilation shortly for use in production environments.

Moreover, there are plans to be able to use a hybrid approach for doing both static compilation and dynamic loading in the same environment, selectively depending on what you want to pre-compile and what you want to load dynamically.


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

  • Static compilation of all CommonJS dependencies into a single JavaScript file.
  • A middleware filter mechanism to include things such as a Google Closure Compiler filter.



MIT License


Brian Noguchi

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