code: public function registerAssets(){
          $view = $this->getView();
          AdminUIMultiselect::register($view);
          //$id = $this->options['id'];
          $inputId = Html::getInputId($this->model,  $this->attribute);
          $js = '$("#'.$inputId.'").asmSelect({
  				addItemTarget: \'bottom\',
  				animate: true,
  				highlight: false,
  				sortable: true,
                                  selectClass:"form-control asmSelect"
  			});';
          
          $view->registerJs($js);
      }
docs: Registers the needed assets