<style>

     .active{

         color: red;

     }

 </style>

 <ul id="app">

     <li v-for='(item,index) in items' @click="change(index)" :class='{active:index===number}'> <!--通过切换索引值改变class-->

     　　<span v-html="item.name"></span>

     </li>

 </ul> 

 <script>

     new Vue({

         el: '#app',

         data: {

             number: 0,

         items:[

         {

             name: "我是0",

         },

         {

             name: "我是1"

         },

         {

             name: "我是2"

             }

         ]

         },

         methods: {

             change: function(index) {

                 this.number= index;

         }

     }

 })

 </script>