code: protected function execute($method, $selector = '', array $arguments = [])
      {
          return $this->context->executeJs("return !object.$method(!args);", [
              '!object' => $this->getInstance($selector),
              // Remove "[" character from start of the string and "]" from the end.
              '!args' => substr(drupal_json_encode($arguments), 1, -1),
          ]);
      }
docs: @param string $method
  WYSIWYG editor method.
  @param string $selector
  Editor selector.
  @param array $arguments
  Arguments for method of WYSIWYG editor.
  
  @throws \Exception
  Throws an exception if the editor does not exist.
  
  @return string
  Result of JS evaluation.