```
<!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="https://cdn.bootcss.com/vue/2.5.18-beta.0/vue.js"></script>
<style>
.show{
background: red;
}
</style>
</head>
<body>
<div id="app">
<p :class="{show:isShow}" @click="handleClick">hello world</p>
</div>
<script>
new Vue({
el:"#app",
data:{
isShow:false
},
methods:{
handleClick(){
this.isShow = !this.isShow
}
}
})
</script>
</body>
</html>
```
