before unmount react use effect code example

Example 1: useeffect umnount

useEffect(() => {
    return () => {
      console.log("cleaned up");
    };
  }, []);

Example 2: useeffect react

useEffect(() => {
  window.addEventListener('mousemove', () => {});

  // returned function will be called on component unmount 
  return () => {
    window.removeEventListener('mousemove', () => {})
  }
}, [])