template模块代码

<template>
  <div>
    <div>
      <div ref="getheight" style="height:50px;background:#f00">固定栏</div>
      <van-tabs
        @click="onClick"
        :sticky="true"
        :duration="0"
        :swipe-threshold="5"
        :offset-top="this.heightall"
        class="seckilling-tab"
      >
        <van-tab v-for="(item,index) in tabs" :key="index" :title="tabs[index]">
          <div style="height:1000px">内容{{index}}</div>
        </van-tab>
      </van-tabs>
    </div>
  </div>
</template>

js模块代码

<script>
export default {
  data() {
    return {
      heightall: 0,
      tabs: {
        0: '选项0',
        1: '选项1',
        2: '选项2',
        3: '选项3',
        4: '选项4'
      }
    }
  },
  mounted() {
    this.$nextTick(function() {
      this.heightall = this.$refs.getheight.offsetHeight
      console.log(this.heightall)
    })
  },
  methods: {
    onClick(name) {}
  }
}
</script>

效果