react useeffect effect specific code example

Example 1: react run useeffect only once

useEffect(() => {
    // Initialization code comes here
}, []);

Example 2: useeffect react

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

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