code: protected function getClientOptions()
      {
          $filterUrl = isset($this->filterUrl) ? $this->filterUrl : Yii::$app->request->url;
          $id = $this->filterRowOptions['id'];
          $filterSelector = "#$id input, #$id select";
          if (isset($this->filterSelector)) {
              $filterSelector .= ', ' . $this->filterSelector;
          }
  
          return [
              'filterUrl' => Url::to($filterUrl),
              'filterSelector' => $filterSelector,
          ];
      }
docs: Returns the options for the grid view JS widget.
  @return array the options