微信小程序锚点选择导航栏

<view class='box'>
    <scroll-view scroll-y scroll-with-animation style="width:25%">
        <view class='nav'>
            <view wx:for="{{navList}}" wx:key='index' class="title {{index == active ?'select':''}}"
                data-index='{{index}}' bindtap='activeNav'>{{item}}</view>
        </view>
    </scroll-view>
    <scroll-view scroll-y style="width:75%" scroll-with-animation scroll-into-view="{{selectId}}"
        bindscroll="watchScroll">
        <view class='content'>
            <view id='{{"item"+index}}' class='subtitle' wx:for="{{navList}}" wx:key='index'>{{item}}</view>
        </view>
    </scroll-view>
</view>

.box {
    display: flex;
}

.nav {
    height: 100vh;
    width: 100%;
    background: #F5F5F5;
    display: flex;
    flex-direction: column;
}

.title {
    width: 100%;
    height: 120rpx;
    line-height: 120rpx;
    text-align: center;
}

.select {
    background: #fff;
    border-left: 5rpx solid #16BA98;
    box-sizing: border-box;
}

.content {
    padding: 0 30rpx;
    box-sizing: border-box;
    width: 100%;
    height: 100vh;
}

.subtitle {
    width: 100%;
    height: 650rpx;
    border-bottom: 10rpx #f5f5f5 solid;
}

Page({
  data: {
    heightArr: [],
    distance: 0,
    active: 0,
    selectId: "item0",
    navList: ['语文', '数学', '英语', '历史', '体育', '音乐']
  },

  onLoad: function (options) {
    this.selectHeight();
  },

  // 选择左侧标签锚点定位
  activeNav(e) {
    var index = e.currentTarget.dataset.index
    this.setData({
      active: index,
      selectId: "item" + index
    })
  },

  //计算右侧每个锚点的高度
  selectHeight() {
    var list = []
    var height = 0;
    const query = wx.createSelectorQuery();
    query.selectAll('.subtitle').boundingClientRect()
    query.exec((res) => {
      res[0].forEach((item) => {
        height += item.height;
        list.push(height)
      })
      this.data.heightArr = list
    })
  },

  //监听scroll-view的滚动事件
  watchScroll(e) {
    let scrollTop = e.detail.scrollTop; //获取距离顶部的距离
    let active = this.data.active;
    if (scrollTop >= this.data.distance) {
      if (active + 1 < this.data.heightArr.length && scrollTop >= this.data.heightArr[active]) {
        this.setData({
          active: active + 1
        })
      }
    } else {
      if (active - 1 >= 0 && scrollTop < this.data.heightArr[active - 1]) {
        this.setData({
          active: active - 1
        })
      }
    }
    this.data.distance = scrollTop;
  }
})