docs: def js_query(self, query: str) -> Awaitable:
          """Send query to related DOM on browser.
  
          :param str query: single string which indicates query type.
          """
          if self.connected:
              self.js_exec(query, self.__reqid)
              fut = Future()  # type: Future[str]
              self.__tasks[self.__reqid] = fut
              self.__reqid += 1
              return fut
          f = Future()  # type: Future[None]
          f.set_result(None)
          return f