<body>
<div id="root">
姓：<input type="text" v-model="firstName"><br/><br/>
名：<input type="text" v-model="lastName"><br/><br/>
全名：<span>{{fullName}}</span><br/><br/>
</div>
</body>
<script>
const vm = new Vue({
el:'#root',
data:{
firstName: '张',
lastName: '三',
fullName:'张-三'
},
watch:{
firstName(newValue){
setTimeout(()=>{
this.fullName = newValue+'-'+this.lastName
},1000);
},
lastName(newValue){
this.lastName = this.firstName+'-'+newValue
}
}
})
</script>效果：更改姓之后延迟一秒显示改后的全名
