設置默認第一個樣式爲active
<!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>
<style>
.active {
color: crimson;
}
</style>
</head>
<body>
<div id="app">
<ul>
<li v-for="(item,index) in movies" :class="{active:currentIndex===index}" @click="change(index)">
<!-- 解釋:active:currentIndex===index -->
<!-- 判斷當前索引值和currentIndex的值是否相等,得到布爾值true或false,來確定當前的li標籤的樣式爲active -->
<!-- 要使第一個li標籤的style樣式爲active,那麼設置currentIndex的默認值爲index的第一個值,“0” -->
<!-- 以此類推,要使第二個li標籤的style樣式爲active,那麼設置currentIndex的默認值爲index的第二個值,“1” -->
{{item}}
</li>
</ul>
</div>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<script>
const app = new Vue({
el: '#app',
data: {
movies: ['大話西遊', '喜劇之王', '整蠱之王', '長江七號'],
currentIndex: 0,
},
methods: {
change(index) {
this.currentIndex = index
//注意點擊事件要傳入參數index,是當前的li標籤的索引值,讓後函數中讓當前的索引值和currentIndex的值相等,得到布爾值爲true,使當前的樣式爲active
}
}
})
</script>
</body>
</html>