code: function(options) {
              var $this = this;
              setTimeout(function() {
                  $this.items = $this.listContainer.children('li').addClass('ui-listbox-item ui-corner-all');
                  $this.choices = $this.element.children('option');
                  $this._unbindItemEvents();
                  $this._bindItemEvents(this.items);
              }, 50);
          }
docs: primeng