code: function() {
        var injectionFragment = document.createDocumentFragment();
        // Clearing the DOM will reduce the repaints needed as we detach each item view.
        this.$el.empty();
  
       _.each(this.modelsToRender(), function(model) {
          var itemView = this.getItemViewFromModel(model);
          if (itemView) {
            // detach to be safe, but during a render, the item views will already be detached.
            itemView.detach();
            this.registerTrackedView(itemView, { shared: false });
            itemView.attachTo(null, {
              replaceMethod: function($el) {
                injectionFragment.appendChild($el[0]);
              },
              discardInjectionSite: true
            });
          }
        }, this);
        this.__updateOrderedModelIdList();
        return $(injectionFragment);
      }
docs: Creates a DOM fragment with each item view appended in the order defined by
  modelsToRender(). This will clear the List View's DOM and invoke the necessary
  detach, register and render logic on each item view.
  @return a DOM fragment with item view elements appended
  @method __emptyAndRebuildItemViewsFragment
  @private