Vue3之watch

  watch监视ref函数

<template>
    <h2>当前求和为：{{sum}}</h2>
    <button @click="sum++">点我+1</button>
    <hr>
    <h2>当前的信息为：{{msg}}</h2>
    <button @click="msg+='！'">修改信息</button>
    <hr>
    <h2>姓名：{{person.name}}</h2>
    <h2>年龄：{{person.age}}</h2>
    <h2>薪资：{{person.job.j1.salary}}K</h2>
    <button @click="person.name+='~'">修改姓名</button>
    <button @click="person.age++">增长年龄</button>
    <button @click="person.job.j1.salary++">涨薪</button>
</template>

<script>
    import {ref,reactive,watch} from 'vue'
    export default {
        name: 'Demo',
        setup(){
            //数据
            let sum = ref(0)
            let msg = ref('你好啊')
            let person = ref({
                name:'张三',
                age:18,
                job:{
                    j1:{
                        salary:20
                    }
                }
            })

            console.log(person) 

           // 监视多个ref定义的响应式数据
            watch([sum,msg],(newValue,oldValue)=>{
                console.log('sum或msg变化了',newValue,oldValue)
            }) 
            watch(sum,(newValue,oldValue)=>{
                console.log('sum的值变化了',newValue,oldValue)
            })

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


            //返回一个对象（常用）
            return {
                sum,
                msg,
                person
            }
        }
    }
</script>

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