<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<script src="./lib/vue-2.4.0.js"></script>
</head>
<body>
<div id="app">
<input type="text" v-model="firstname"> +
<input type="text" v-model="lastname"> =
<input type="text" v-model="fullname">
</div>
<script>
// 创建 Vue 实例，得到 ViewModel
var vm = new Vue({
el: '#app',
data: {
firstname: '',
lastname: '',
fullname: ''
},
methods:{},
watch:{ //使用这个属性，可以监视 data 中指定数据的变化，然后触发这个 watch 中对应的 function 处理函数
'firstname':function(newVal,oldVal){
//console.log('监视到了 fiestname 的变化')
//this.fullname=this.firstname+'-'+this.lastname
//console.log(newVal+'-'+oldVal)
this.fullname=newVal+'-'+this.lastname
},
'lastname':function(newVal){
this.fullname=this.firstname+'-'+newVal
}
}
});
</script>
</body>
</html>