Wrong usage of useEffect in custom hook docs

The Building Your Own Hooks page suggests invoking the useEffect hook without passing in an empty dependency array

function useFriendStatus(friendID) {
  const [isOnline, setIsOnline] = useState(null);

  useEffect(() => {
    function handleStatusChange(status) {
      setIsOnline(status.isOnline);
    }

    ChatAPI.subscribeToFriendStatus(friendID, handleStatusChange);
    return () => {
      ChatAPI.unsubscribeFromFriendStatus(friendID, handleStatusChange);
    };
  });

  return isOnline;
}

As there is no dependency array passed to useEffect, this would cause multiple multiple un/subscribe API calls. Shouldn't the example snippet have an empty dependency array?

首先查看链接的 Building Your Own Hooks 页面以及 issue 中展示的 useEffect 示例。根据文档所述的 hook 行为确认依赖数组指南，然后在需要时更新示例，使其 subscription 生命周期正确，并且页面不再暗示会重复创建 subscription。