vue3 dom ref 实现，子组件ref实现，defineExpose暴露子组件作用域

示例代码

App.vue

<template>
  <header>
    <img alt="Vue logo" class="logo" src="@/assets/logo.svg" width="125" height="125" />

    <div class="wrapper">
      <HelloWorld ref="HelloWorldRef" msg="You did it!" />

      <nav>
        <RouterLink to="/">Home</RouterLink>
        <RouterLink to="/about">About</RouterLink>
      </nav>
    </div>
  </header>

  <RouterView />
</template>


<script lang="tsx" setup>
import { ref } from "vue"
import { RouterLink, RouterView } from 'vue-router'
import HelloWorld from './components/HelloWorld.vue'

//父组件声明一个HelloWorldRef自动绑定到dom上的ref
const HelloWorldRef = ref(null)

console.log(HelloWorldRef, "HelloWorldRef")


</script>


<style scoped>
header {
  line-height: 1.5;
  max-height: 100vh;
}

.logo {
  display: block;
  margin: 0 auto 2rem;
}

nav {
  width: 100%;
  font-size: 12px;
  text-align: center;
  margin-top: 2rem;
}

nav a.router-link-exact-active {
  color: var(--color-text);
}

nav a.router-link-exact-active:hover {
  background-color: transparent;
}

nav a {
  display: inline-block;
  padding: 0 1rem;
  border-left: 1px solid var(--color-border);
}

nav a:first-of-type {
  border: 0;
}

@media (min-width: 1024px) {
  header {
    display: flex;
    place-items: center;
    padding-right: calc(var(--section-gap) / 2);
  }

  .logo {
    margin: 0 2rem 0 0;
  }

  header .wrapper {
    display: flex;
    place-items: flex-start;
    flex-wrap: wrap;
  }

  nav {
    text-align: left;
    margin-left: -1rem;
    font-size: 1rem;

    padding: 1rem 0;
    margin-top: 1rem;
  }
}
</style>

子组件HelloWorld.vue

defineExpose 暴露子组件可以让父组件访问的作用域

<template>
  <div class="greetings">
    <h1 class="green">{{ msg }}</h1>
    <h3>
      You’ve successfully created a project with
      <a href="https://vitejs.dev/" target="_blank" rel="noopener">Vite</a> +
      <a href="https://vuejs.org/" target="_blank" rel="noopener">Vue 3</a>.
    </h3>
    <div>{{ abd }}</div>
  </div>
</template>


<script lang="tsx" setup>
import {ref} from "vue"
defineProps({
  msg: {
    type: String,
    required: true
  }
})

let abc=ref<string>("abc")

console.log(abc.value,"value")

let abd=ref("abd")


defineExpose({
  abc:abc
})
</script>

<style scoped>
h1 {
  font-weight: 500;
  font-size: 2.6rem;
  position: relative;
  top: -10px;
}

h3 {
  font-size: 1.2rem;
}

.greetings h1,
.greetings h3 {
  text-align: center;
}

@media (min-width: 1024px) {
  .greetings h1,
  .greetings h3 {
    text-align: left;
  }
}
</style>