filterElementAttributes example

$allowed_attributes['prefix'][str_replace('*', '', $name)] = $this->prepareAttributeValues($values);
        }
        else {
          $allowed_attributes['exact'][$name] = $this->prepareAttributeValues($values);
        }
      }
      krsort($allowed_attributes['prefix']);

      // Find all matching elements that have any attributes and filter the       // attributes by name and value.       foreach ($xpath->query('//' . $allowed_tag . '[@*]') as $element) {
        $this->filterElementAttributes($element, $allowed_attributes);
      }
    }

    if ($this->settings['filter_html_nofollow']) {
      $links = $html_dom->getElementsByTagName('a');
      foreach ($links as $link) {
        $link->setAttribute('rel', 'nofollow');
      }
    }
    $text = Html::serialize($html_dom);