<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>属性绑定和双向数据绑定</title>
<script src="./vue.js"></script>
</head>
<body>
<div id ="root"></div>
<div v-bind:title="title">hello world</div>
<script>
new Vue({
el:"#root",
data:{
title:"this is a apple"
}
})
</script>
</body>
</html>
解决啦，应该把
<div v-bind:title="title">hello world</div>
放在id为root的div中