定义一个组件，然后监听滚动事件

<template>
  <div class="nav-bar" :class="{'is_fixed':isFixed}">
    <div class="container">
      <div class="pro-title">
        小米8
      </div>
      <div class="pro-param">
        <a href="javascript:;">概述</a>
        <a href="javascript:;">参数</a>
        <a href="javascript:;">用户评价</a>
        <slot name="buy"></slot>
      </div>
    </div>
  </div>
</template>

<script>
// scoped
export default {
  name: 'productParam',
  props: {
    title: String
  },
  data () {
    return {
      isFixed: false
    }
  },
  methods: {
    initHeight () {
      const scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop
      if (scrollTop > 152) {
        this.isFixed = true
      } else {
        this.isFixed = false
      }
    }
  },
  mounted () {
    window.addEventListener('scroll', this.initHeight)
  },
  unmounted () {
    // false 冒泡
    window.removeEventListener('scroll', this.initHeight, false)
  }
}
</script>

<style lang="scss">
@import '../assets/scss/config.scss';
@import '../assets/scss/mixin.scss';
  .nav-bar {
    height: 70px;
    line-height: 70px;
    border-top: 1px solid $colorH;
    background-color: $colorG;
    &.is_fixed {
      position: fixed;
      top: 0;
      width: 100%;
      box-shadow: 0 5px 5px $colorE;
    }
    .container {
      @include flex();
      .pro-title {
        font-size: $fontH;
        color: $colorB;
        font-weight: 700;
      }
      .pro-param {
        font-size: $fontJ;
        a {
          color: $colorC;
          position: relative;
          margin-right: 14px;
          &::after {
            content: '';
            position: absolute;
            top: 3px;
            left: -7px;
            width: 1px;
            height: 10px;
            background-color: $colorC;
          }
          &:first-child::after {
              display: none;
          }
        }
      }
    }
  }

</style>

插槽用法

<template>
  <div class="product">
    <product-param>
      <template v-slot:buy>
        <button class="btn">立即购买</button>
      </template>
    </product-param>
    <div class="h">123</div>
    </div>
</template>