code: function(){
  
      var routes = this.current ? (this.current.data.routes || {}) : {};
          routes[this._previousRoute] = '';
  
      // Unset Previous Application's Routes. For each route in the page app, remove
      // the handler from our route object and delete our referance to the route's callback
      _.each(routes, (value, key) => {
        var regExp = this._routeToRegExp(key).toString();
        Backbone.history.handlers = _.filter(Backbone.history.handlers, function(obj){
          return obj.route.toString() !== regExp;
        });
      });
  
      if(!this.current){ return void 0; }
  
      var oldPageName = this.current.__pageId;
  
      // Un-hook Event Bindings, Delete Objects
      this.current.data.deinitialize();
  
      // Now we no longer have a page installed.
      this.current = undefined;
  
      // Disable old css if it exists
      setTimeout(() => {
        if(this.status === ERROR){ return void 0; }
        document.getElementById(oldPageName + '-css').setAttribute('disabled', true);
      }, 500);
  
    }
docs: De-initializes the previous app before rendering a new app This way we can ensure that every new page starts with a clean slate This is crucial for scalability of a single page app.