Simple NodeJS combo handler for YUI 3 (or anything, really).

node-combo.js

#!/usr/bin/env node

/**
 * Simple YUI combo handler using NodeJS and Express. Stick a caching and
 * compressing proxy in front of this and you're ready to rock in production.
 *
 * Copyright (c) 2010 Ryan Grove <ryan@wonko.com>
 *
 * 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.
 */

var express = require('express'),
    fs      = require('fs'),
    path    = require('path'),

// Port to listen on.
PORT = 8000,

// Absolute path to the public root directory.
// ROOT_PATH = '/home/node/public/yui',
ROOT_PATH = '/Users/rgrove/src/yui',

// Absolute path to the public YUI3 directory.
YUI3_PATH = ROOT_PATH + '/yui3',

// -- Express app and middleware -----------------------------------------------
app = express.createServer(
  // express.logger(),
  express.staticProvider(ROOT_PATH),
  express.conditionalGet()
);

// -- Routes -------------------------------------------------------------------
app.get('/yui3', function (req, res) {
  comboHandler(YUI3_PATH, req, res);
});

// -- Functions ----------------------------------------------------------------
var defaultMimeType = 'application/octet-stream',

    mimeTypes = {
      '.css' : 'text/css',
      '.js'  : 'application/javascript',
      '.json': 'application/json',
      '.txt' : 'text/plain',
      '.xml' : 'application/xml'
    };

function comboHandler(rootPath, req, res) {
  var body    = [],
      query   = parseQuery(req.url),
      pending = query.length,
      type    = pending && getMimeType(path.extname(query[0])),

      lastModified;

  if (!pending) {
    res.send(400);
  }

  function finish() {
    if (lastModified) {
      res.header('Last-Modified', lastModified.toUTCString());
    }

    res.send(body.join("\n"), {
      'Content-Type': type + ';charset=utf-8'
    });
  }

  function notFound() {
    res.send(400);
  }

  query.forEach(function (relativePath, i) {
    var absolutePath;

    // Skip empty params.
    if (!relativePath) {
      pending -= 1;
      return;
    }

    absolutePath = path.normalize(path.join(rootPath, relativePath));

    // Don't allow traversal above the root path.
    if (absolutePath.indexOf(rootPath) !== 0) {
      res.send(403); // TODO: nicer error handling
      return;
    }

    fs.readFile(absolutePath, 'utf8', function (err, data) {
      if (err) { return notFound(); }

      body[i] = data;

      fs.stat(absolutePath, function (err, stats) {
        var mtime;

        if (!err) {
          mtime = new Date(stats.mtime);

          if (!lastModified || mtime > lastModified) {
            lastModified = mtime;
          }
        }

        pending -= 1;

        if (pending === 0) {
          finish();
        }
      });
    });
  });
}

function decode(string) {
  return decodeURIComponent(string).replace(/\+/g, ' ');
}

function getMimeType(extension) {
  extension = (extension.charAt(0) === '.' ? extension : '.' + extension).toLowerCase();
  return mimeTypes[extension] || defaultMimeType;
}

// Because querystring.parse() is stupid.
function parseQuery(url) {
  var parsed = [],
      query  = url.split('?')[1];

  if (query) {
    query.split('&').forEach(function (item) {
      parsed.push(decode(item.split('=')[0]));
    });
  }

  return parsed;
}

app.listen(PORT);