vue 侦听器watch 之 深度监听 deep

<template>

  <div>
    <p>FullName: {{person.fullname}}</p>
    <p>FirstName: <input type="text" v-model="person.firstname"></p>
  </div>

</template>

<script>
    export default {
        data(){
            return {
                person: {
                    firstname: ‘Menghui‘,
                    lastname: ‘Jin‘,
                    fullname: ‘‘
                }
            }
          },
          watch: {
              person: {
                  handler(n,o){
                      this.person.fullname = n.firstname + ‘ ‘ + this.person.lastname;
                  },
                  // immediate: true,  //刷新加载 立马触发一次handler
                  // deep: true  // 可以深度检测到 person 对象的属性值的变化
              }
          }

    }
</script>