1.父子组件如何通信?

props

$emit

2.父子组件嵌套下的生命周期?

一个完整的父子组件生命周期:
父beforeCreate -> 父created-> 父beforeMount ->

子beforeCreate -> 子created -> 子beforeMount -> 子mounted -> 父mounted->

父beforeUpdate->子beforeUpdate->子updated->父updated->

父beforeDestroy->子beforeDestroy->子destroyed->父destroyed