导入约束文件时v-on报错，但可以正常运行
<!DOCTYPE html>
<meta charset="UTF-8" xmlns:v-on="http://www.w3.org/1999/xhtml">
<title>Title</title>
</head>
<body>
<!--view层 模板-->
<div id="app">
<!--v-on后面跟事件的类型-->
<button v-on:click="sayHi">Click Me</button>
</div>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<script>
var vm = new Vue({
el:"#app",
data:{
message:"hello 点击事件"
},
methods:{
sayHi:function (event) {
alert(this.message);
}
}
});
</script>
</body>
</html>
