一、完整代码

<template>
  <div class="about">
    <h1>Computed的用法</h1>
    <h3>姓:{{ person.firstName }}</h3>
    <input type="text" v-model="person.firstName">
    <h3>名:{{ person.lastName }}</h3>
    <input type="text" v-model="person.lastName">
    <div v-if="person.fullName">
      <h3>全名:{{ person.fullName }}</h3>
      <input type="text" v-model="person.fullName">
    </div>
  </div>
</template>

<script>
import { reactive, computed } from 'vue';

export default {
  name:'aboutPage',
  setup() {
    let person = reactive({
      firstName: '张',
      lastName: '三'
    })

    person.fullName = computed({
      get() {
        return person.firstName + '-' + person.lastName
      },
      set(value) {
        const nameArr = value.split('-')
        person.firstName = nameArr[0]
        person.lastName = nameArr[1]
      }
    })

    return {
      person
    }
  }
}
</script>

二、主要代码

get：访问了这个属性

set：修改这个属性时操作的业务逻辑

person.fullName = computed({
  get() {
    return person.firstName + '-' + person.lastName
  },
  set(value) {
    const nameArr = value.split('-')
    person.firstName = nameArr[0]
    person.lastName = nameArr[1]
  }
})

三、效果