30-seconds-of-code/snippets/useOnWindowScroll.md

title, tags, author, cover, firstSeen

title	tags	author	cover	firstSeen
React useOnWindowScroll hook	hooks,effect,event	chalarangelo	planning	2021-12-08T05:00:00-04:00

Executes a callback whenever the window is scrolled.

• Use the useRef() hook to create a variable, listener, which will hold the listener reference.
• Use the useEffect() hook and EventTarget.addEventListener() to listen to the 'scroll' event of the Window global object.
• Use EventTarget.removeEventListener() to remove any existing listeners and clean up when the component unmounts.

const useOnWindowScroll = callback => {
  const listener = React.useRef(null);

  React.useEffect(() => {
    if (listener.current)
      window.removeEventListener('scroll', listener.current);
    listener.current = window.addEventListener('scroll', callback);
    return () => {
      window.removeEventListener('scroll', listener.current);
    };
  }, [callback]);
};

const App = () => {
  useOnWindowScroll(() => console.log(`scroll Y: ${window.pageYOffset}`));
  return <p style={{ height: '300vh' }}>Scroll and check the console</p>;
};

ReactDOM.render(<App />, document.getElementById('root'));