• 作用：实现祖与后代组件间通信

• 套路：父组件有一个 provide 选项来提供数据，后代组件有一个 inject 选项来开始使用这些数据

• 具体写法：

  1. 祖组件中：

setup(){
	......
    let car = reactive({name:'奔驰',price:'40万'})
    provide('car',car)
    ......
}

2. 后代组件中：

setup(props,context){
	......
    const car = inject('car')
    return {car}
	......
}

App.vue

<template>
	<div class="app">
		<h3>我是App组件(祖),{{name}}--{{ price }}</h3>
		<Child></Child>
	</div>
</template>

<script>
	import {reactive,toRefs,provide} from 'vue'
	import Child from './components/Child.vue'
	export default {
		name: 'App',
		components:{Child},
		setup() {
			let car=reactive({name:'奔驰',price:'40W'})
			provide('car',car) //给自己的后代组件传递数据
			return {...toRefs(car)}
		}
	}
</script>
<style scoped>
	.app{
		background-color: gray;
		padding: 10px;
	}
</style>

Child.vue

<template>
	<div class="child">
		<h3>我是Child组件（子）</h3>
		<Son/>
	</div>
</template>

<script>
	import {inject} from 'vue'
	import Son from './Son.vue'
	export default {
		name:'Child',
		components:{Son},
		/* setup(){
			let x = inject('car')
			console.log(x,'Child-----')
		} */
	}
</script>

<style>
	.child{
		background-color: skyblue;
		padding: 10px;
	}
</style>

son.vue

<template>
	<div class="son1">
		<h3>我是Son组件（孙），{{car.name}}--{{ car.price }}</h3>
	</div>
</template>

<script>
	import {inject} from 'vue'
	export default {
		name:'Son',
		setup(){
			let car = inject('car')	
			console.log('@@@',car)
			return {car}
		} 
	}
</script>

<style>
	.son1{
		background-color: orange;
		padding: 10px;
	}
</style>