28.循环时选中一个按钮改变他的样式

单选

html
      <div class="button"
        v-for="(item, index) in cateGoryList"
        :key="item.index"
        @click="selectItemClick(index)"
        :class= "{'active':checked === index}"
      >
      {{item}}
      </div>

  script
 // 选中按钮
    selectItemClick (index) {
      this.checked = index
    }

<style scoped lang='less'>
  .active{
    background-color: gray;
  }
</style>