Require.js for ben

routerExtend.js

//You are using underscores extend so you need include it :)
define(['underscore'], function(_) {
  
  //This could be some kind of utilities modules
  
  //Define the extend method
  var extend = function() {
    _.extend(Backbone.Router.prototype, Backbone.Events, {
      before: function() {},
      after: function() {},
      route: function(route, name, callback) {
        Backbone.history || (Backbone.history = new Backbone.History);
        if (!_.isRegExp(route)) route = this._routeToRegExp(route);
        if (!callback) callback = this[name];
        Backbone.history.route(route, _.bind(function(fragment) {
          var that = this;
          var args = this._extractParameters(route, fragment);
          if (_(this.before).isFunction()) {
            this.before.apply(this, args);
          }
          if (callback) callback.apply(that, args);
          if (_(this.after).isFunction()) {
            this.after.apply(this, args);
          }
        }, this));
      }
    });
  }
  
  //Add the extend method to this modules public methods
  return {
    extend: extend
  };
  
});

someOtherFile.js

//Some other app init file
define(['backbone', 'utils/routerExtend'], function(Backbone, routerExtend) {
  
  //Extend router
  routerExtend.extend.call(this);
  
});