Vue点击切换颜色的方法

<template>
 <div>
 <div v-for="(list,index) in siYuan" class="aa" :class="{ red:changeRed == index}" @click="change(index)">{{list.a}}</div>
 </div>
</template>
 
<script>
export default {
 data(){
 return{
 siYuan:[
 {"a":"田"},
 {"a":"心"},
 {"a":"水"},
 {"a":"原"}
 ],
 changeRed:-1
 }
 },
 methods:{
 change(index){
 this.changeRed = index;
 }
 }
 
}
</script>
 
<style>
 .aa{
 cursor: pointer;
 }
 .red{
 color: red;
 }
</style>