This is a simple combo handler for Node.js, usable either as Connect middleware or as an Express server. It works just like the combo handler service on the Yahoo! CDN, which you'll be familiar with if you've used YUI.

The combo handler is compatible with the YUI Loader, so you can use it to host YUI, or you can use it with any other JavaScript or CSS if you're willing to construct the combo URLs yourself.

The combo handler itself doesn't perform any caching or compression, but stick Nginx or something in front of it and you should be ready to rock in production.

Install using npm:

npm install combohandler

Or just clone the GitHub repo:

git clone git://github.com/rgrove/combohandler.git

The combohandler module provides a configurable Connect middleware that can be used to add combo handling capability to any Connect-based request handler (like Express).

The combohandler/lib/server module creates a standalone Express server instance, or augments an existing server, to perform combo handling for a set of configurable routes.

The combo handler middleware can be used as application-wide middleware for all routes:

var combo = require('combohandler');
app.use(combo.combine({rootPath: '/local/path/to/files'}));

Or as route middleware for a specific route:

app.get('/foo', combo.combine({rootPath: '/local/path/to/foo'}), function (req, res) {
    res.send(res.body);
});

In either case, the middleware will perform combo handling for files under the specified local rootPath when requested using a URL with one or more file paths in the query string:

http://example.com/<route>?<path>[&path][...]

For example:

http://example.com/foo?file1.js
http://example.com/foo?file1.js&file2.js
http://example.com/foo?file1.js&file2.js&subdir/file3.js

Attempts to traverse above the rootPath or to request a file that doesn't exist will result in a BadRequest error being bubbled up.

Here's a basic Express app that uses the combo handler as route middleware for multiple routes with different root paths:

var combo   = require('combohandler'),
    express = require('express'),

    app = express();

app.configure(function () {
  app.use(express.errorHandler());
});

// Return a 400 response if the combo handler generates a BadRequest error.
app.use(function (err, req, res, next) {
    if (err instanceof combo.BadRequest) {
        res.charset = 'utf-8';
        res.type('text/plain');
        res.send(400, 'Bad request.');
    } else {
        next();
    }
});

// Given a root path that points to a YUI 3 root folder, this route will
// handle URLs like:
//
// http://example.com/yui3?build/yui/yui-min.js&build/loader/loader-min.js
//
app.get('/yui3', combo.combine({rootPath: '/local/path/to/yui3'}), function (req, res) {
    res.send(res.body);
});

app.listen(3000);

If you just want to get a server up and running quickly by specifying a mapping of routes to local root paths, use the combohandler/lib/server module. It creates a barebones Express server that will perform combo handling on the routes you specify:

var comboServer = require('combohandler/lib/server'),
    app;

app = comboServer({
    roots: {
        '/yui3': '/local/path/to/yui3'
    }
});

app.listen(3000);

If you already have an existing Express server instance and just want to add some combo handled routes to it easily, you can augment your existing server with combo handled routes:

var comboServer = require('combohandler/lib/server');

comboServer({
    roots: {
        '/yui3': '/local/path/to/yui3'
    }
}, myApp); // Assuming `myApp` is a pre-existing Express server instance.

If you clone or download the GitHub repo, you can rename config.sample.js to config.js, edit it to your liking, and then simply run app.js to start a standalone server in development mode on port 8000.

git clone git://github.com/rgrove/combohandler.git
cd combohandler
mv config.sample.js config.js
./app.js

To run the standalone server in production mode, set the NODE_ENV variable to production before running it:

NODE_ENV=production ./app.js

Because the combo handler changes the path from which CSS files are loaded, relative URLs in CSS files need to be updated to be relative to the combohandled path. Set the basePath configuration option to have the combo handler do this automatically.

// This static route can be used to load images and other assets that shouldn't
// be combined.
//
app.use('/public', express.static(__dirname + '/public'));

// This route will combine requests for files in the public directory, and will
// also automatically rewrite relative paths in CSS files to point to the
// non-combohandled static route defined above.
//
app.get('/combo', combohandler.combine({
    rootPath: __dirname + '/public',
    basePath: '/public'
}), function (req, res) {
    res.send(res.body);
});

With a tiny bit of configuration, you can tell YUI to use your custom combo handler instead of the Yahoo! combo handler. Here's an example:

<script src="http://example.com/combo/yui3?build/yui/yui-min.js"></script>
<script>
YUI({
    comboBase: 'http://example.com/combo/yui3?',
    combine  : true,
    root     : 'build/'
}).use('node', function (Y) {
    // YUI will now automatically load modules from the custom combo handler.
});
</script>

Copyright (c) 2012 Yahoo! Inc. All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.