vue3 父子组件传值详解

<!-- 父组件 -->
<template>
  <div>
    <children :title="title" @getChildren="getChildren"></children>
    <div>子组件说： {{ childrenAsk }}</div>
  </div>
</template>
 
<script>
  import children from "./children.vue"
  export default {
    data() {
      return {
        title: "我是父组件传过来的值",
        childrenAsk: ""
      }
    },
    methods: {
      getChildren(val) {
        this.childrenAsk = val
      }
    }
  }
</script>

<!-- 子组件 -->
<template>
  <div>
    <div>父组件传过来的值： {{ title }}</div>
    <button @click="askToFather">点击发送给父组件</button>
  </div>
</template>
<script>
  export default {
    props: {
      title: {
        type: String
      }
    },
    data() {
      return {
        askMsg: "这是我给父组件说的话"
      }
    },
    methods: {
      askToFather() {
        this.$emit("getChildren", this.askMsg)
      }
    }
  }
</script>

<template>
  <div style="color: aqua">父组件</div>
  <div>子组件对我说：{{ children_msg }}</div>
  <children :title="msg" @listen="listenToChildren"></children>
  {{ value }}
</template>
<script lang="ts">
import children from "@/views/component_emit/children.vue"
import { defineComponent, ref } from "vue"
export default defineComponent({
  components: {
    children,
  },
  name: "father",
  setup() {
    let msg = "我是父组件"
    let children_msg = ref("") // ref的作用是实现响应式， 如果没有ref则不能实现响应式（引用数据类型用reactive）
    let listenToChildren = (val) => {
      children_msg.value = val // 使用ref包裹的数据，需要通过.value的形式访问他的值
    }
    return {
      msg,
      children_msg,
      listenToChildren,
    }
  },
})
</script>
<style></style>

<template>
  <div style="color: brown">子组件</div>
  <!-- 父传子使用方法和vue2相同 -->
  <div>父组件传过来的值为：{{ title }}</div>
  <button @click="sayToFather">向父组件说话</button>
</template>
<script lang="ts">
import { defineComponent } from "vue"
export default defineComponent({
  name: "children",
  props: {
    title: {
      type: String,
    },
  },
  setup(props, context) {
    // context作用是获取上下文对象，
    // 如果setup写法为setup(props, { emit })的方式的话，下面的context可以省略
    const sayToFather = () => {
      const ask = "我是子组件，我对父组件说话"
      context.emit("listen", ask)
    }
    return {
      sayToFather,
    }
  },
})
</script>
<style></style>