vue3组合式api ＜script setup＞ props 父子组件的写法

父组件传入子组个的变量， 子组件是无法直接修改的， 只能通过 emit的方式， 让父组件修改， 之后子组件更新

<template>
  <div class="parent">
    我是父组件
    <son :msg="msg" :obj="obj" @changemsgEmit="changemsgEmit" @changeobjnameEmit="changeobjnameEmit" @changeobjageEmit="changeobjageEmit"></son>
  </div>
</template>

<script setup>
  import {ref, reactive} from "vue";
  import son from "./son.vue"

  let msg = ref("this msg form parent.vue");

  let obj = reactive({
    name:"huang",
    age:39
  })

  const changeobjageEmit = (params)=>{
    obj.age = params;
  }

  const changeobjnameEmit = (params)=>{
    obj.name = params.newname;
  }

  const changemsgEmit = (params)=>{
    console.log(params);
    msg.value = params.join("");
  }

</script>

<style scoped>

</style>

父组件的写法没有变， 子组件的写法就有很大的变化了

<template>
  <div class="son">son
    {{msg}}
    <hr/>
    {{obj.name}}
    {{obj.age}}
  </div>
  <button @click="changemsg">changemsg</button>
  <button @click="changeobjname(3)" type="button">changeobjname</button>
  <button @click="changeobjage(42)" type="button">changeobjage</button>
</template>

<script setup>
//这里定义了一个 props来接收传来的属性
//使用时可以是 {{msg}}  也可以使用 {{props.msg}}
  let props = defineProps({
    msg:{
      type:String,
      default:""
    },
    obj:{
      type:Object,
      default:{}
    }
  })

  //这里定义了三个自定义事件
  const emit = defineEmits(["changeobjnameEmit","changeobjageEmit","changemsgEmit"]);


  //下面是通过事件调用了三个自定义的事件
  const changeobjname = ()=>{
    let objname = {newname:"hahaha"}
    emit("changeobjnameEmit",objname)
  }

  const changeobjage = (age)=>{
    emit("changeobjageEmit",age)
  }

  const changemsg = ()=>{
    emit("changemsgEmit",["aa","bb","cc"]);
  }


</script>