<view class="container">
  <view class="category-left">
    <scroll-view scroll-y="true" style="height:100%">
      <block wx:for="{{category}}" wx:key="id">
       <view class="catgegory-item {{activeId === item.id?'active-item':''}}" data-id="{{item.id}}" bindtap="clickItem">{{item.name}}</view>
      </block>
    </scroll-view>
  </view>
  <view class="category-right">
    <scroll-view scroll-y="true" style="height:100%" scroll-into-view="{{toView}}" scroll-with-animation="ture" bindscroll="scroll">
      <view class="categoty-detail">
      <block wx:for="{{content}}" wx:key="id">
        <view class="catefory-main">
          <view class="category-title" id="{{item.id}}">{{item.title}}</view>
          <view class="category-content">
              <view class="content-item" wx:for="{{item.options}}" wx:for-item="i" wx:key="id">
                <image src="{{i.src}}"></image>
                <text>{{i.text}}</text>                                                      
              </view>
          </view>
        </view> 
      </block>
      </view>
    </scroll-view>
  </view>
</view>

//index.js
//获取应用实例
const app = getApp()

Page({
  data: {
    toView: 'a1',
    activeId: 'a1',
    category: [
      {name: '新品', id: 'a1'},
      { name: '众筹', id: 'a2' },
      { name: '小米手机', id: 'a3' },
      { name: 'redmi手机', id: 'a4' },
      { name: '黑鲨游戏', id: 'a5' },
      { name: "手机配件", id: 'a6' },
      { name: '电视', id: 'a7'},
      { name: '电脑', id: 'a8' },
    ],
    content: [
      {
        title: '- 新品 -', 
        options: [
          { src: '../../image/redmi.png',id: '001',text: 'redmi8'},
          { src: '../../image/redmi.png', id: '002', text: 'redmi8A' },
          { src: '../../image/redmi.png', id: '003', text: '小米9pro 5G'},
          { src: '../../image/redmi.png', id: '004', text: 'redmi8'},
          { src: '../../image/redmi.png', id: '005',text: 'redmi8' }
        ],
        id: 'a1'
      },
      {
        title: '- 众筹 -',
        options: [
          { src: '../../image/zhongchou.png', id: '006', text: 'redmi8' },
          { src: '../../image/zhongchou.png', id: '007' ,text: 'redmi8'},
          { src: '../../image/zhongchou.png', id: '008', text: 'redmi8' },
          { src: '../../image/zhongchou.png', id: '009',text: 'redmi8' }
        ],
        id: 'a2'
      },
      {
        title: '- 小米手机 -',
        options: [
          { src: '../../image/xiaomi.png', id: '006', text: 'redmi8' },
          { src: '../../image/xiaomi.png', id: '007', text: 'redmi8' },
          { src: '../../image/xiaomi.png', id: '008', text: 'redmi8' },
          { src: '../../image/xiaomi.png', id: '009', text: 'redmi8' }
        ],
         id: 'a3'
      },
      {
        title: '- redmi手机 -',
        options: [
          { src: '../../image/hongmi.png', id: '006', text: 'redmi8' },
          { src: '../../image/hongmi.png', id: '007', text: 'redmi8' },
          { src: '../../image/hongmi.png', id: '008', text: 'redmi8' },
          { src: '../../image/hongmi.png', id: '009', text: 'redmi8' }
        ],
        id: 'a4'
      }

    ],
  },
  //事件处理函数
  onLoad: function () {
    this.setData({
      toView: 'a1',
      heightArr: []
    })
    let query = wx.createSelectorQuery();
    query.selectAll('.catefory-main').boundingClientRect((rect)=> {
      rect.forEach(ele => {
        this.calculateHeight(ele.height);
      })
    }).exec();
  },
  clickItem(e) {
    this.setData({
      activeId: e.currentTarget.dataset.id,
      toView: e.currentTarget.dataset.id
    })
  },
  scroll(e) {
    let scrollHeight = e.detail.scrollTop;
    let index = this.calculateIndex(this.data.heightArr,scrollHeight);
    this.setData({
      activeId: 'a'+index
    })

  },
  // 计算滚动的区间
  calculateHeight(height) {
    if(!this.data.heightArr.length) {
      this.data.heightArr.push(height)
    }else {
      this.data.heightArr.forEach(ele => {
        height += ele
      })
      this.data.heightArr.push(height);
    }
  },
  // 计算左边选中的下标
  calculateIndex(arr, scrollHeight) {
    let index= '';
    for(let i =0;i<arr.length;i++) {
      if (scrollHeight >= 0 && scrollHeight < arr[0]){
        index = 0;
      }else if(scrollHeight >= arr[i-1] && scrollHeight < arr[i]){
        index = i;
      }
    }
    return index+1;
  }
})

/**index.wxss**/
.container {
  padding: 0;
  width:100%;
  height: 100vh;
  display: flex;
  flex-direction: row;
  align-items: flex-start;
}
.category-left {
  height: 100%;
  width: 22%;
  padding: 0 20rpx;
  box-sizing: border-box;
  border-right: 1px solid #efefef;
}
.catgegory-item {
  padding: 20rpx 0;
  font-size: 30rpx;
  text-align:  center;
}
.active-item {
  color: orange;
}
.category-right {
  flex:1;
  height: 100%;
}
.category-content {
  display: grid;
  grid-template-columns: repeat(auto-fill, 190rpx);
}
.category-title {
  text-align: center;
}
.content-item {
  display: flex;
  flex-direction: column;
  padding: 20rpx;
  text-align: center;
  font-size: 30rpx;
}
.content-item image{
  width: 120rpx;
  height: 120rpx;
}