title: Loading Backbone and Underscore using RequireJS
body: <p>I'm trying to load Backbone and Underscore (as well as jQuery) with RequireJS. With the latest versions of Backbone and Underscore, it seems kind of tricky. For one, Underscore automatically registers itself as a module, but Backbone assumes Underscore is available globally. I should also note that Backbone doesn't seem to register itself as a module which makes it kind of inconsistent with the other libs. This is the best main.js I could come up with that works:</p>
  
  <pre><code>require(
  {
      paths: {
          'backbone': 'libs/backbone/backbone-require',
          'templates': '../templates'
      }
  },
  [
      // jQuery registers itself as a module.
      'http://cdnjs.cloudflare.com/ajax/libs/jquery/1.7/jquery.min.js',
  
      // Underscore registers itself as a module.
      'http://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.2.1/underscore-min.js'
  ], function() {
  
      // These nested require() calls are just due to how Backbone is built.  Underscore basically says if require()
      // is available then it will automatically register an "underscore" module, but it won't register underscore
      // as a global "_".  However, Backbone expects Underscore to be a global variable.  To make this work, we require
      // the Underscore module after it's been defined from within Underscore and set it as a global variable for
      // Backbone's sake.  Hopefully Backbone will soon be able to use the Underscore module directly instead of
      // assuming it's global.
      require(['underscore'], function(_) {
          window._ = _;
      });
  
      require([
          'order!http://cdnjs.cloudflare.com/ajax/libs/backbone.js/0.5.3/backbone-min.js',
          'order!app'
      ], function(a, app) {
          app.initialize();
      })
  });
  </code></pre>
  
  <p>I should mention that, while it works, the optimizer chokes on it.  I receive the following: </p>
  
  <pre><code>Tracing dependencies for: main
  js: "/home/httpd/aahardy/requirejs/r.js", line 7619: exception from uncaught JavaScript throw: Error: Error: Error evaluating module "undefined" at location "/home/httpd/aahardy/phoenix/trunk/ui/js/../../ui-build/js/underscore.js":
  JavaException: java.io.FileNotFoundException: /home/httpd/aahardy/phoenix/trunk/ui/js/../../ui-build/js/underscore.js (No such file or directory)
  fileName:/home/httpd/aahardy/phoenix/trunk/ui/js/../../ui-build/js/underscore.js
  lineNumber: undefined
  http://requirejs.org/docs/errors.html#defineerror
  In module tree:
      main
  </code></pre>
  
  <p>Is there a better way of handling this?  Thanks!</p>