v-for循环列表，展开样式随手风琴

 <div class="product_box" v-for="(item,index) of kinds" :key="index">
    <div class="main_top">
        <div class="title_bottom">
        <el-button
            round
            @click="nowBorrowFn(index)"
            :class="{btn_box:index === 0 ? show3 : show4}"
        >立即借款</el-button>
        </div>
    </div>
    <el-collapse-transition>
        <div v-show="item.flag">
        </div>
    </el-collapse-transition>
</div>

<script>
    nowBorrowFn(index){
        let flag = this.kinds[val].flag;
          this.kinds.forEach(item => {
            item.flag = false;
          });
          this.kinds[val].flag = !flag;
    }
</script>

渲染时需要给v-show一个默认的参数

//来自：https://blog.csdn.net/weixin_42550863/article/details/81980094