可以把页面代码和组件代码放自己项目里跑一下

页面代码

<template>
  <view class="Tracing-detail">
    
    <view class="title" v-for="i in 30">顶部信息</view>
    <!-- tab按钮 -->
    <Tab v-model="activeIndex" @change="scrollToTarget"></Tab>
    <!-- 产品详情 -->
    <view class="cpxq" id="cpxq">
      <view class="title" v-for="i in 30">产品详情</view>
    </view>
    <!-- 流程溯源 -->
    <view class="lcsy" id="lcsy">
      <view class="title" v-for="i in 30">流程溯源</view>
    </view>
    <!-- 主体信息 -->
    <view class="ztxx" id="ztxx">
      <view class="title" v-for="i in 30">主体信息</view>
    </view>
    <!-- 优品推荐 -->
    <view class="yptj" id="yptj">
      <view class="title" v-for="i in 30">优品推荐</view>
    </view>
  </view>
</template>

<script>
  import variables from 'uni.scss';
  import Tab from './components/Tab.vue';
  import Certificate from './components/Certificate.vue'
  import Flow from './components/Flow.vue'
  export default {
    components:{
      Tab,
      Certificate,
      Flow
    },
    data(){
      return {
        
        cpxqTop:0,
        lcsyTop:0,
        ztxxTop:0,
        yptjTop:0,
        activeIndex:1
      }
    },
    mounted() {
      this.init()
    },
    onPageScroll(e) {
        // e.scrollTop 是页面在垂直方向已滚动的距离（单位px）
        // console.log(e.scrollTop);
      if(e.scrollTop<this.lcsyTop){
        if(this.activeIndex!=1) this.activeIndex = 1
      }else if(e.scrollTop<this.ztxxTop){
        if(this.activeIndex!=2) this.activeIndex = 2
      }else if(e.scrollTop<this.yptjTop){
        if(this.activeIndex!=3) this.activeIndex = 3
      }else if(this.activeIndex!=4){
        if(this.activeIndex!=4) this.activeIndex = 4
      }
    },
    methods:{
      init(){
        this.getTopNumber()
      },
      getTopNumber(){
        // 创建查询对象
        const query = uni.createSelectorQuery().in(this);
        // 选择目标元素并获取其位置信息
        query.select('#cpxq').boundingClientRect(data => {
          if (data) {
            console.log(data,1);
          this.cpxqTop = data.top-30
          }
        }); // 执行查询
        query.select('#lcsy').boundingClientRect(data => {
          if (data) {
            console.log(data,2);
          this.lcsyTop = data.top-30//30为tab的高度
          }
        }); // 执行查询
        query.select('#ztxx').boundingClientRect(data => {
          if (data) {
            console.log(data,3);
          this.ztxxTop = data.top-30
          }
        }); // 执行查询
        query.select('#yptj').boundingClientRect(data => {
          if (data) {
            console.log(data,4);
          this.yptjTop = data.top-30
          }
        }).exec(); // 执行查询
      },
      scrollToTarget(i) {
        console.log(i);
        let number = ''
        if(i==1){
          number = this.cpxqTop
        }else if(i==2){
          number = this.lcsyTop
        }else if(i==3){
          number = this.ztxxTop
        }else if(i==4){
          number = this.yptjTop
        }
          uni.pageScrollTo({
            scrollTop: number, // pageScrollTop为页面当前已滚动的距离
            duration: 300 // 滚动动画时长
          });
      }
    }
  }
</script>

<style scoped lang="scss">
  .title{
    text-align: center;
  }
</style>

吸顶按钮组件代码

<template>
  <view class="tab-list">
    <view 
    :class="item.index==value?'tab-active': 'tab'" 
    v-for="(item,index) in list"
    @click="btnClick(item.index)">
      {{item.name}}
    </view>
  </view>
</template>

<script>
  export default {
    props:{
      value:{
        typeof:Number,
        default:1
      }
    },
    data(){
      return{
        list:[
          {
            index:1,
            name:'产品详情'
          },
          {
            index:2,
            name:'流程溯源'
          },
          {
            index:3,
            name:'主体信息'
          },
          {
            index:4,
            name:'优品推荐'
          }
        ]
      }
    },
    methods:{
      btnClick(i){
        this.$emit("input", i)
        this.$emit("change", i)
      }
    }
  }
</script>

<style scoped lang="scss">
  .tab-list{
    position: sticky;
    top: 0;
    z-index: 999;
    margin: 0 31rpx;
    height: 79rpx;
    padding: 0 17rpx;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: red;
    background-size: 100% 100%;
    .tab-active {
      position: relative;
      height: 44rpx;
      font-family: YouSheBiaoTiHei;
      font-size: 35rpx;
      color: #FEE858;
      line-height: 44rpx;
      text-align: center;
      font-style: normal;
    }
    .tab {
      position: relative;
      height: 44rpx;
      font-family: YouSheBiaoTiHei;
      font-size: 35rpx;
      color: #FFFFFF;
      line-height: 44rpx;
      text-align: center;
      font-style: normal;
    }
  }
</style>