vue3 watch 用法

<script setup>
    import {
      reactive,
      watch,
    } from 'vue'
     //数据
     let sum = ref(0)
     let msg = ref('你好啊')
     let person = reactive({
                    name:'张三',
                    age:18,
                    job:{
                      j1:{
                        salary:20
                      }
                    }
                  })
    // 两种监听格式
    watch([sum,msg],(newValue,oldValue)=>{
            console.log('sum或msg变了',newValue,oldValue)
          },{immediate:true})

     watch(()=>person.job,(newValue,oldValue)=>{
        console.log('person的job变化了',newValue,oldValue)
     },{deep:true})