竞态问题 取消上次请求

原文 overreacted.io/zh-hans/a-c…

function Article({ id }) {
  const [article, setArticle] = useState(null);

  useEffect(() => {
    let didCancel = false;
    async function fetchData() {
      const article = await API.fetchArticle(id);
      if (!didCancel) {        setArticle(article);
      }
    }

    fetchData();

    return () => {      didCancel = true;    };  }, [id]);

  // ...
}