node package manager


Generate and serve combo URLs across CDNs


Several public CDNs host popular JS libs, most notably Until now there was no easy way to combo the various libs into a single URL in order to maximize performance. This package fills that gap by generating and serving combo URLs across various CDNs and any other public server.


$ npm i cmbn


This software is currently demoed at but there are no guarantees to availability. It's recommended to install cmbn on your own host in order to enable comboing with application-specific assets. To maximize performance even further cmbn should be fronted by a CDN like CloudFlare.

Standalone server

var cmbn = require('cmbn');

In addition to the options available for middleware ,createServer accepts one or more of the following:

  • port - Port to listen on. Default is 80.
  • staticDir - Directory to serve static assets from. Particularly useful if comboing from localhost.
  • staticMaxAge - Number of seconds to set for maxAge in the Cache-Control header if serving local assets.


var connect = require('connect'),
    express = require('express'),
    cmbn = require('cmbn'),
    app = express.createServer();


middleware takes an optional argument which is an object containing one or more of the following:

  • cacheSize - The size in bytes to reserve for the lru-cache which stores external assets which have been fetched. Default is 5000000 (~5MB).
  • cacheFunc -The cache function used to determine the size of each asset, default is to return item.length.

Node Client

var cmbn = require('cmbn'),
    url = cmbn.client.combine([


combine also takes an optional argument which is an object containing one or more of the following:

  • host - The hostname[:port] which is running cmbn. Defaults to (see note under Usage).
  • protocol - The protocol for the host running cmbn. Defaults to http.

Browser Client

<script src=""></script>
var url = cmbn.client.combine([


See Node Client.

Adding a CDN

var cmbn = require('cmbn');
// add cdn for localhost
cmbn.cdns.addCdn('lh', {host: 'localhost:8080', prefix: 'libs/'});

var url = cmbn.client.combine([
], {host: 'localhost:8080'});

// http://localhost:8080/~gg;jquery,1.7.2,jquery.min.js/~lh;cmbn,0.0.1,cmbn.min.js

Run the Example

After installing the package run node examples from the package root. A link will be output by the client and the server will start. Copy the link and paste it into a browser to see the comboed output.


See the examples folder and code for more usage information.


MIT License. See the accompanying LICENSE file for terms.