4.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="vue.js"></script>

    


</head>
<body>

<div id="app">
    {{ message }}
</div>



<script>


    var app = new Vue({
        el: '#app',
  
        beforeCreate(){

        },
        created(){

        },
        beforeMount(){

        },
        mounted: ()=> { //挂载元素，获取到DOM节点
//           setTimeout(()=>{
//                this.count+=1;
//                console.log('this.count='+this.count)
//           },5000)
        },
        beforeUpdate(){

        },
        updated(){ //挂载元素，获取到DOM节点
        },
        beforeDestroy(){

        },
        destroyed(){

       },
        data: {
            count:0,
            message: 'Hello Vue!'
        }
    })

</script>

</body>
</html>