<!--  -->            
        <div class="menulist">
            <!--  -->
                <scroll-view scroll-y="true"  class="left" >
                  <block v-for="item in menu" :key="item">
                    <view class="menuList">
                      <view class="menu" :class="selected==index?"selected":""" :data-index="index" @click="turnMenu">
                          {{item.cate_name}}
                      </view>
                    </view>
                  </block>
                </scroll-view>

            <!--  -->
            <scroll-view class="right" scroll-y="true">
                <!-- <view class="title">{{menu[selected].cate_name}}</view> -->
                <view class="title">{{selected}}</view>
              <block v-for="(item,k) in menu" :key="k">
                <navigator url="/pages/shoppingdetail/main">
                <view class="food">
                
                </view>
                </navigator>
              </block>
            </scroll-view>

this is the data format returned by the background. Ask the great god for advice.