React Tutorial - 12.life cycle - 16.4+ new
1.download new version recat libraries from react official doc - cdn links, and run new dependecies on older life cycle source code file
2.UNSAFE -- will be decrepit -- componentWillUpdate / componentWIllReceiveProps / componentWillMount
3..new hooks -- rarely used -- getDerivedStateFromProps / getSnapshotBeforeUpdate
4.most important hooks -- componentDidMount / render / componentWillUnmount