useUpdateLayoutEffect

挂载完成后，在依赖更新的时候执行

Usage

即時編輯器

function Demo() {
  const [count, setCount] = useState(0);
  const [layoutEffectCount, setLayoutEffectCount] = useState(0);
  const [updateLayoutEffectCount, setUpdateLayoutEffectCount] = useState(0);

  useLayoutEffect(() => {
    setLayoutEffectCount(c => c + 1);
  }, [count]);

  useUpdateLayoutEffect(() => {
    setUpdateLayoutEffectCount(c => c + 1);
    return () => {
      // do something
    };
  }, [count]); // you can include deps array if necessary

  return (
    <div>
      <p>layoutEffect計數：{layoutEffectCount}</p>
      <p>更新layoutEffect計數：{updateLayoutEffectCount}</p>
      <p>
        <button type="button" onClick={() => setCount(c => c + 1)}>
          重新渲染
        </button>
      </p>
    </div>
  );
};

結果

layoutEffect計數：1

更新layoutEffect計數：0