react生命周期

https://www.jianshu.com/p/514fe21b9914

初始化：constructor

挂载：
componentWillMount 只会调用一次

render

componentDidMount
组件挂载到DOM后调用，且只会被调用一次

更新
componentWillReceiveProps

componentShouldUpdate

componentWillUpdate
render
componentDidUpdate

shoudComponentUpdate
https://www.cnblogs.com/penghuwan/p/6707254.html