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

title, tags

title	tags
useComponentWillUnmount	hooks,effect,beginner

A hook that executes a callback immediately before a component is unmounted and destroyed.

• Use React.useEffect() with an empty array as the second argument and return the provided callback to be executed only once before cleanup.

const useComponentWillUnmount = onUnmountHandler => {
  React.useEffect(() => () => {
    onUnmountHandler()
  }, []);
}

const Unmounter = () => {
  useComponentWillUnmount(() => console.log('Component will unmount'));

  return <div>Check the console!</div>;
}

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