combohandler

Combo Handler

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.

Installation

Install using npm:

npm install combohandler

Or just clone the GitHub repo:

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

Usage

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.

As Express middleware

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'}), combo.respond);

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. ' + err.message);
    } else {
        next(err);
    }
});

// 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'}), combo.respond);

app.listen(3000);

combo.respond

The respond method exported by require('combohandler') is a convenience method intended to be the last callback passed to an express route. Unless you have a very good reason to avoid it, you should probably use it. Here is the equivalent callback:

function respond(req, res) {
    res.send(res.body);
}

This method may be extended in the future to do fancy things with optional combohandler middleware.

Creating a server

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);

Augmenting an existing server

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.

Running the included standalone server

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

Rewriting URLs in CSS files

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', combo.combine({
    rootPath: __dirname + '/public',
    basePath: '/public'
}), combo.respond);

Alternatively, you can use the built-in cssUrls middleware as a separate route callback. cssUrls must always be placed after the default combine middleware when used in this fashion.

// This route provides the same behaviour as the previous example, providing
// better separation of concerns and the possibility of inserting custom
// middleware between the built-in steps.
app.get('/combo',
    combo.combine({
        rootPath: __dirname + '/public'
    }),
    combo.cssUrls({
        basePath: '/public'
    }),
    combo.respond);

Finally, the cssUrls middleware has the ability (disabled by default) to rewrite @import paths in the same manner as url() values. As @import is considered an anti-pattern in production code, this functionality is strictly opt-in and requires passing true as the rewriteImports property in the middleware options object.

// Automagically
app.get('/combo', combo.combine({
    rootPath: __dirname + '/public',
    basePath: '/public',
    rewriteImports: true
}), combo.respond);

// As explicit middleware
app.get('/combo',
    combo.combine({ rootPath: __dirname + '/public' }),
    combo.cssUrls({ basePath: '/public', rewriteImports: true }),
    combo.respond);

Dynamic Paths via Route Parameters

To enable resolution of dynamic subtree paths under a given rootPath, simply add a route parameter to both the route and the rootPath config.

app.get('/combo/yui/:version', combo.combine({
    rootPath: '/local/path/to/yui/:version/build'
}), combo.respond);

Given this config, any YUI release tarball you explode into a versioned subdirectory of /local/path/to/yui/ would be available under a much shorter URL than the default config provides:

http://example.com/combo/yui/3.9.1?yui/yui-min.js&yui-throttle/yui-throttle-min.js
// vs
http://example.com/combo/yui?3.9.1/build/yui/yui-min.js&3.9.1/build/yui-throttle/yui-throttle-min.js

If the built-in dynamicPath middleware is used manually, it must be inserted before the default combine middleware.

Using as a YUI 3 combo handler

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>

License

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.