需求：
点击某行，某行应用不同样式
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
.active {
color: red;
}
</style>
</head>
<body>
<div id="app">
<ul>
<li v-for = '(i,index) in movies'
:class = '{active : currentIndex === index}'
@click = 'btn(index)'
>{{i}}</li>
<!-- 把currentindex 和index对比，相同的设置样式 -->
</ul>
</div>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<script>
const app = new Vue({
el : '#app',
data : {
movies : ['movie1','movie2','movie3','movie4'],
currentIndex : 2,
//当前选择是哪一个
},
methods :{
btn(index) {
this.currentIndex = index;
}
}
})
</script>
</body>
</html>