右侧快速入口滑动时左侧跟着变化

 <!--右侧字母-->
       <div class="list-shortcut" >
         <ul>
           <li  v-for="(item,index) of shortcutList"     @touchstart.stop.prevent="onShortcutTouchStart"   @touchmove.stop.prevent="onShortcutTouchMove"   :data-index="index"  class="item">{{item}}</li>
         </ul>
       </div>




事件方法：
  onShortcutTouchStart(e){
        let anchorIndex = getData(e.target, 'index')
        // this.$refs.listview.scrollToElement(this.$refs.listGroup[anchorIndex],0)
        // 右侧滑动代码
        let firstTouch = e.touches[0]
        this.touch.y1 = firstTouch.pageY
        this.touch.anchorIndex = anchorIndex
        this. _scrollTo(anchorIndex)
      },
      onShortcutTouchMove(e){
        let firstTouch = e.touches[0]
        this.touch.y2 = firstTouch.pageY
        let delta = (this.touch.y2 - this.touch.y1) / ANCHOR_HEIGHT | 0//移动的了几个字母；/18移动了几个锚点
        let anchorIndex = parseInt(this.touch.anchorIndex) + delta
        this. _scrollTo(anchorIndex)
      },
      _scrollTo(index){
        this.$refs.listview.scrollToElement(this.$refs.listGroup[index],0)
      }