provide()
提供一个值，可以被后代组件注入。
inject()
注入一个由祖先组件或整个应用 (通过 app.provide()) 提供的值。
下面是一个例子
App.vue
<script setup lang="ts">
import { ref, provide } from "vue"
import Child from "./Child.vue"
const count = ref(1)
provide("count", count)
setInterval(() => {
count.value++
}, 1000)
</script>
<template>
<Child />
</template>
Child.vue
<script setup lang="ts">
// Add a piece of code to make the `count` value get injected into the child component.
import {inject} from 'vue'
const count = inject('count')
</script>
<template>
{
{ count }}
</template>
