监听窗口位置

function useScrollPostion() {
  const [scrollX, setScrollX] = useState(0);

  const [scrollY, setScrollY] = useState(0);

  useEffect(() => {
    function handleScroll() {
      setScrollX(window.scrollX);
      setScrollY(window.scrollY);
    }
    window.addEventListner("scroll", handleScroll);
    return () => {
      window.removeEventListner("scroll", handleScroll);
    };
  }, []);

  return [scrollX, scrollY];
}