vue回到顶部监听滚动事件详解

<template><div class="tools"><ul @mouseleave="mouseLeave()"><li @click="toTop(step)">回到顶部</li><li @mouseover="mouseOver(1)">QQ</li><li @mouseover="mouseOver(2)">微信</li></ul><div v-if="showIndex === 1">玩QQ</div><div v-if="showIndex === 2">玩微信</div></div></template>

<script>export default { name: 'FloatTools', props: { step: { //此数据是控制动画快慢的  type: Number,  default: 50 } }, data() { return {  isActive: false,  showIndex:0//默认显示下标 } }, methods: { toTop(i) {  //参数i表示间隔的幅度大小，以此来控制速度   document.documentElement.scrollTop -= i;  if (document.documentElement.scrollTop > 0) {  var c = setTimeout(() => this.toTop(i), 16);  } else {  clearTimeout(c);  } }, handleScroll() {  //获取滚动距顶部的距离，显示  let scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop；  if (scrollTop > 60) {  this.isActive = true;  } else {  this.isActive = false;  } }, mouseOver(index) { //鼠标移到哪个工具上，对应内容显示出来  this.showIndex = index; }, mouseLeave(){ //鼠标移出工具区域后1秒，内容区域消失   let timer = setTimeout(() => {   this.showIndex = 0;   clearTimeout(timer)  }, 500); } }, mounted: function () { window.addEventListener('scroll', this.handleScroll, true); // 监听（绑定）滚轮滚动事件 }, destroyed() { window.removeEventListener('scroll', this.handleScroll); //离开页面需要移除这个监听的事件 }}</script>