vue.js 3.2.22：平滑回到顶部

一，代码：

GoTop.vue

<template>
  <div style="100%;height:100vh;background: #ffff00;display: flex;flex-direction: column;">
    <!--用来标记顶部位置的元素-->
    <div id="topdiv" style="0px;height:0px;"></div>
    <img style="100%;" src="http://www.chenmaner.com/images/portfolio/003.jpg" />
    <img style="100%;" src="http://www.chenmaner.com/images/portfolio/004.jpg" />
    <img style="100%;" src="http://www.chenmaner.com/images/portfolio/005.jpg" />
    <img style="100%;" src="http://www.chenmaner.com/images/portfolio/006.jpg" />
    <img style="100%;" src="http://www.chenmaner.com/images/portfolio/007.jpg" />
    <img style="100%;" src="http://www.chenmaner.com/images/portfolio/008.jpg" />
    <img style="100%;" src="http://www.chenmaner.com/images/portfolio/009.jpg" />
    <img style="100%;" src="http://www.chenmaner.com/images/portfolio/010.jpg" />

    <!--回到顶部的按钮-->
    <div @click="goTop" v-if="showToScroll" class="el-backtop" style="position:fixed;40px;height:40px;right: 40px; bottom: 40px;">
      <i class="el-icon el-backtop__icon">
        <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1024 1024"><path fill="#409eff" d="M512 320 192 704h639.936z"></path></svg>
      </i>
    </div>

  </div>
</template>

<script>
import {ref,onMounted,onUnmounted } from 'vue';
export default {
  name: "Image",
  setup() {
    onMounted(()=>{
      //添加滚动事件
      window.addEventListener('scroll',handleScroll,false)
    })
    onUnmounted(()=>{
      //移除滚动事件
      window.removeEventListener('scroll',handleScroll)
    })
    //回到顶部的按钮是否显示
    const showToScroll = ref(false);
    //处理滚动，决定回到顶部的按钮是否显示出来
    let handleScroll = () => {
      if (document.documentElement.scrollTop > 60) {
        showToScroll.value = true;
      } else {
        showToScroll.value = false;
      }
    }
    //回到顶部
    const goTop = () => {
      document.querySelector("#topdiv").scrollIntoView({
        behavior: "smooth",  // 平滑过渡
        block:    "start"  // 
      });
    }
    return {
      showToScroll,
      goTop,
    }
  }
}
</script>

<style scoped>
.el-backtop {
  position: fixed;
  background-color: #ffffff;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  color: #409eff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  box-shadow: 0 0 6px #0000001f;
  cursor: pointer;
  z-index: 5;
}
.el-backtop:hover {
  background-color: #f2f6fc;
}
.el-backtop__icon {
  font-size: 20px;
}

.el-icon {
  height: 1em;
  width: 1em;
  line-height: 1em;
  text-align: center;
  display: inline-block;
  position: relative;
  fill: currentColor;
  color: #409eff;
}
</style>

说明：刘宏缔的架构森林是一个专注架构的博客，地址：https://www.cnblogs.com/architectforest

         对应的源码可以访问这里获取： https://github.com/liuhongdi/
         或: https://gitee.com/liuhongdi

说明：作者:刘宏缔 邮箱: 371125307@qq.com

二，测试效果

位于顶部时：回到顶部的悬浮按钮默认不显示

滑动离开顶部时，按钮显示:

 此时点击按钮会滑动回顶部

三，查看vue的版本:

lazy@0.1.0 /data/vue/lazy
├─┬ @vue/cli-plugin-babel@4.5.15
│ └─┬ @vue/babel-preset-app@4.5.15
│   └── vue@3.2.22 deduped
└─┬ vue@3.2.22
    └─┬ @vue/server-renderer@3.2.22
      └── vue@3.2.22 deduped