backbone.js sub routing

app.js

/* Pretend app setup stuff is here */

/* Kick off app */
jQuery(function($) {

  var Gallery = app.module("gallery");

  app.Router = Backbone.Router.extend({
    initialize: function() {
      this.gallery = new Gallery.Router("gallery/");
    }
  });

  // Actually initialize
  new app.Router();

});

gallery.js

(function(Gallery) {

  var Helper = app.module("helper");

  Gallery.Router = Helper.SubRoute.extend({
    routes: {
      "": "list",
      "add": "add",
      "filter": "filter"
    }
  });

})(app.module("gallery"));

helper.js

(function(Helper) {

  Helper.SubRoute = Backbone.Router.extend({
    constructor: function(prefix) {
      var routes = {};

      // Prefix is optional, set to empty string if not passed
      prefix = prefix || "";

      // Allow for optionally omitting trailing /.  Since base routes do not
      // trigger with a trailing / this is actually kind of important =)
      if (prefix[prefix.length-1] == "/") {
        prefix = prefix.slice(0, prefix.length-1);

      // If a prefix exists, add a trailing /
      } else if (prefix) {
        prefix += "/";
      }

      // Every route needs to be prefixed
      _.each(this.routes, function(callback, path) {
        if (path) {
          return routes[prefix + path] = callback;
        }

        // If the path is "" just set to prefix, this is to comply
        // with how Backbone expects base paths to look gallery vs gallery/
        routes[prefix] = callback;
      });

      // Must override with prefixed routes
      this.routes = routes;

      // Required to have Backbone set up routes
      Backbone.Router.prototype.constructor.call(this);
    }
  });

})(app.module("helper"));