微信小程序商城分类滚动列表锚点的项目实践

        <view class="content">
          <!-- 左侧分类 -->
            <scroll-view scroll-y scroll-with-animation class="left" style="height:{{height}}rpx;" scroll-into-view='{{leftId}}'>
              <view id='left{{index}}' class="left-item {{activeKey===index?'active':''}}" wx:for="{{navData}}" data-index='{{index}}' wx:key='id' bindtap="onChange">
                <text class='name'>{{item.name}}</text>
              </view>
            </scroll-view>
            <!-- 滚动列表 -->
            <scroll-view class="right" scroll-y scroll-with-animation scroll-into-view="{{selectedId}}" bindscroll="changeScroll" style='height:{{height}}rpx;'>
            <!-- 每个分类 -->
              <view class="item" wx:for="{{goodslist}}" wx:key="id" id='type{{index}}'>
              <!-- 分类标题 -->
                <view class="type">【{{item.name}}】</view>
                <!-- 分类下的商品 -->
                <view class="item-list">
                  <navigator  class="list-item" wx:for="{{item.list}}" wx:for-item='key' wx:key="id" url='/pages/goods/goods?id={{key.id}}'>
                    <image style="width: 100%; height: 180rpx;" src="{{key.imgurl}}" />
                    <view class="item-name">{{key.goods_name}}</view>
                  </navigator>
                </view>
                <view wx:if="{{item.list.length===0}}" class="nodata">
                  暂无商品
                </view>
              </view>
            </scroll-view>
          </view>

        .content {
            width: 100%;
            height: calc(100% - 108rpx);
            overflow-y: hidden;
            display: flex;

            .left {
              height: 100%;
              overflow-y: scroll;
              .left-item {
                width: 100%;
                padding: 20rpx;
                box-sizing: border-box;

                .name {
                  word-wrap: break-word;
                  font-size: 28rpx;
                  color: #323233;
                }
              }

              .active {
                border-left: 6rpx #ee0a24 solid;
                background-color: #fff;
              }
            }

            .right {
              flex: 1;

              .item {
                position: relative;
                padding: 20rpx;

                .type {
                  margin-bottom: 10rpx;
                  padding: 5rpx;
                  position: sticky;
                  top: 0;
                  background-color: #fff;
                }

                .item-list {
                  width: 100%;
                  display: grid;
                  grid-template-columns: 1fr 1fr 1fr;
                  grid-gap: 20rpx;
                  text-align: center;

                  .item-name {
                    color: #3a3a3a;
                    font-size: 26rpx;
                    margin-top: 10rpx;
                  }
                }

                .nodata{
                  padding: 20rpx;
                  color: #ccc;
                }
              }
            }
          }

// 用到的data
data:{
    // 分类列表
    navData:[],
    // 商品列表
    goodslist:[],
    // 左侧分类选中项 分类列表数组的下标
    activeKey:0,
    // 计算出的锚点的位置
    heightList:[],
    // 右侧子元素的锚点
    selectedId: 'type0',
    // 左侧分类的锚点
    leftId:'left0',
    // scroll-view 的高度
    height:0
},
onShow() {
    let Height = 0;
    wx.getSystemInfo({
      success: (res) => {
        Height = res.windowHeight
      }
    })
    const query = wx.createSelectorQuery();
    query.selectAll('.search').boundingClientRect()
    query.exec((res) => {
    // 计算滚动列表的高度  视口高度减去顶部高度 *2是因为拿到的是px 虽然也可以 但是我们通常使用的是rpx
      this.setData({
        height: (Height - res[0][0].height) * 2
      })
    })
},

//计算右侧每个锚点的高距离顶部的高
selectHeight() {
    let h = 0;
    const query = wx.createSelectorQuery();
    query.exec((res) => {
        console.log('res', res)
        let arr=res[0].map((item,index)=>{
            h+ = item.height
            return h
        })
        this.setData({
            heightList: arr,
        })
        console.log('height', this.data.heightList)
    })
},

changeScroll(e) {
    // 获取距离顶部的距离
    let scrollTop = e.detail.scrollTop;
    // 当前分类选中项,分类列表下标
    let {activeKey,heightList} = this.data;
    // 防止超出分类              判断滚动距离是否超过当前分类距离顶部高度
    if (activeKey + 1 < heightList.length && scrollTop >= heightList[activeKey]) {
        this.setData({
            // 左侧分类选中项改变
            activeKey: activeKey + 1,
            // 左侧锚点对应位置
            leftId: `left${activeKey + 1}`
        })
    }
    if (activeKey - 1 >= 0 && scrollTop < heightList\[activeKey - 1]) {
        this.setData({
            activeKey: activeKey - 1,
            leftId: `left${activeKey - 1}`
        })
    }
},

onChange(event) {
    let index = event.currentTarget.dataset.index
    this.setData({
      activeKey: index,
      selectId: "item" + index
    });
},