watch侦听属性数据变动
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>vue1</title> <script src="vue.js"></script> <link rel="stylesheet" type="text/css" href="vue.css"> </head> <body> <div id="app"> <div> <input type="text" v-model="msg"> <button @click="submit">submit</button> <ul> <li v-for="item of list">{{item}}</li> </ul> </div> </div> <script> var app=new Vue({ el:"#app", data:{ msg:'', list:[], }, methods:{ submit:function(){ this.list.push(this.msg), this.msg="" } }, watch:{ list(){ console.log(this.list.length) } } }) </script> </body> </html>