1、绑定点击事件

 <!-- 按钮 -->
    <div class="back">
      <van-button type="primary" @click="toTop">回到顶部</van-button>
    </div>
    <!-- 按钮 end-->

2、方法

export default {
  data() {
    return {
      gotop: false
    };
  },
  mounted() {
    //此处true 需要加上 不加滚动事件可能绑定不成功
    window.addEventListener("scroll", this.handleScroll, true);
  },
  methods: {
    handleScroll() {
      let scrolltop =
        document.documentElement.scrolltop || document.body.scrollTop;
      scrolltop > 30 ? (this.gotop = true) : (this.gotop = false);
    },
    toTop() {
      let top = document.documentElement.scrollTop || document.body.scrollTop;
      //实现滚动效果
      const timeTop = setInterval(() => {
        document.body.scrollTop = document.documentElement.scrollTop = top -= 50;
        if (top <= 0) {
          clearInterval(timeTop);
        }
      }, 10);
    }
  }
};