# Hooks
# How to use componentWillMount() in React Hooks?
// componentWillUnmount is use for cleanup (like removing event listeners, cancel the timer etc). Say you are adding a event listener in componentDidMount and removing it in componentWillUnmount as below.
componentDidMount() {
window.addEventListener('mousemove', () => {})
}
componentWillUnmount() {
window.removeEventListener('mousemove', () => {})
}
// Hook equivalent of above code will be as follows
useEffect(() => {
window.addEventListener('mousemove', () => {});
// returned function will be called on component unmount
return () => {
window.removeEventListener('mousemove', () => {})
}
}, [])