code: public function refresh($anchor = '')
      {
          return Yii::$app->getResponse()->redirect(Yii::$app->getRequest()->getUrl() . $anchor);
      }
docs: Refreshes the current page.
  This method is a shortcut to [[Response::refresh()]].
  
  You can use it in an action by returning the [[Response]] directly:
  
  ```php
  // stop executing this action and refresh the current page
  return $this->refresh();
  ```
  
  @param string $anchor the anchor that should be appended to the redirection URL.
  Defaults to empty. Make sure the anchor starts with '#' if you want to specify it.
  @return Response the response object itself