vue滚动tab跟随切换效果

mounted(){
 //记录每个内容对用的dom数组
 this.arrDom = document.getElementsByClassName("item-content");
 window.addEventListener('scroll', this.handleScroll);
 },
 
 destroyed(){
 window.removeEventListener('scroll', this.handleScroll);
 },

tabList:[{
 id:1,
 name:'详情'
 },{
 id:2,
 name:'评论'
 },{
 id:3,
 name:'新闻'
 },{
 id:4,
 name:'关于'
 },{
 id:5,
 name:'相关'
 }],

 
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handleScroll(){
 let scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop;
 this.headerFixed = scrollTop > this.offsetTop;
 for (let i = 0; i 80){
  if(this.arrDom[i].offsetTop-scrollTop<=80&&this.arrDom[i+1].offsetTop-scrollTop>80){
  this.active = i+1
  }
 }else{
  this.active = this.arrDom.length;
 }
 
 }
 },