React基础知识

React生命周期：参考资料1 参考资料2

1. 挂载卸载过程
	1.1.constructor()
	1.2.componentWillMount()
	1.3.componentDidMount()
	1.4.componentWillUnmount ()
	
2. 更新过程
	2.1. componentWillReceiveProps (nextProps)
	2.2.shouldComponentUpdate(nextProps,nextState)
	2.3.componentWillUpdate (nextProps,nextState)
	2.4.componentDidUpdate(prevProps,prevState)
	2.5.render()
	
3. React新增的生命周期(个人补充)
	3.1. getDerivedStateFromProps(nextProps, prevState)
	3.2. getSnapshotBeforeUpdate(prevProps, prevState)