code: public function registerClientScript()
      {
          $id = $this->options['id'];
          $options = Json::htmlEncode($this->getClientOptions());
          $attributes = Json::htmlEncode($this->attributes);
          $view = $this->getView();
          ActiveFormAsset::register($view);
          $view->registerJs("jQuery('#$id').yiiActiveForm($attributes, $options);");
      }
docs: This registers the necessary JavaScript code.
  @since 2.0.12