<style>

.con{?

? ? ????color: red;

????}?

</style>

<ul id="app">

<li v-for='(item,index) in items'? ? @click="change(index)"? ?:class='{ active:index===number}'>? ? ? ? <!--通過切換索引值改變class-->

　　<span v-html="item.name"></span>

</li>

</ul>

<script>?

????new Vue({?

????????????el: '#app',?

????????????data: {

????????????????????number: 0,? ? //注意此處

????????????????????items:[? {? name: "我是0", },? { name: "我是1"? },? {? name: "我是2"? }? ]?

????????????????},

? ????????????methods: {? ?

????????????????????????change: function(index) {

????????????????????????????????????this.number= index;? ? //重要處

????????????????????????}?

????????????????}?

})?

</script>

參考文章：https://www.cnblogs.com/xueweijie/p/6861702.html