小程序利用scroll-view实现锚点功能

应用场景：横向tab切换时，下面对应的tab_item置顶效果（或者在一定的高度）

index.wxml:
//tab横向导航部分
 <scroll-view class="nav" scroll-x="true" style="height:35px;" scroll-into-view="{{leftView}}" enable-flex="true">
        <view wx:for="{{tab}}" wx:key="index" class='items {{showId == index ? "active" : ""}}' data-id="{{index}}" id="T{{index}}" wx:key="{{index}}" bindtap="scrollTab">{{item}}</view>
</scroll-view>

//纵向内容部分
 <scroll-view class="scroll" scroll-into-view="{{toView}}" scroll-y="true" scroll-with-animation="true" bindscroll="scrollTo">
      <view class="menu_item" wx:for="{{list}}" id="L{{index}}" wx:key="index">
        <text class="title">{{item.name}}</text>
      </view>
</scroll-view>

index.js:
page({
  data:{
    showId: 0,
    leftView:'T0',
    toView: 'L0',
    anchorArray:[ ],
  },
  scrollTab: function (e) {
    const showId = e.currentTarget.dataset.id
    this.setData({
      showId,
      toView: 'L' + showId,
      leftView: 'T' + showId
    })
  },
 //监听滚动时间 判断高度来实现tab高亮
  scrollTo: function (e) {
    let scrollTop = e.detail.scrollTop
    var _this = this
    let scrollArr = _this.data.anchorArray;
    if (scrollTop >= scrollArr[scrollArr.length - 1] - _this.data.autoHeight) {
      return;
    } else {
      for (let i = 0; i < scrollArr.length; i++) {
        if (scrollTop >= 0 && scrollTop < scrollArr[0]) {
          _this.setData({
            showId: 0,
            leftView:'T'+0
          });
        } else if(scrollTop>=scrollArr[i-1]&&scrollTop<scrollArr[i]){
          _this.setData({
            showId: i,
            leftView:'T'+i
          });
        }
      }
    }
    let query = wx.createSelectorQuery().in(_this);
    let heightArr = [];
    let h = 0;
    query.selectAll('.menu_item').boundingClientRect((react) => {
      react.forEach((res) => {
        h += res.height;
        heightArr.push(h)
      })
      _this.setData({
        anchorArray: heightArr
      });
    }).exec();
  },
})

index.wxss:
//去掉滚动条
::-webkit-scrollbar {
  width: 0;
  height: 0;
  color: transparent;
}
！！！scroll-view 父级一定要设置高