<style>
.box{width: 500px;height: 400px;border: solid 1px black;margin: 20px auto;}
.box ul{margin: 0;padding: 0;list-style: none;height: 40px;line-height
:40px;display: flex;background: #ccc;text-align: center;}
.box li{flex:1;border-left: solid 1px black;border-right: solid 1px black;}
.box li.active{background: red;}
.cont div{width: 500px;height: 360px;display: none;}
.cont .cont1{background: #f0f;display: block;}
.cont .cont2{background: #f00;}
.cont .cont3{background: #00f;}
</style>
<body>
<div class="box">
<ul><li class="active">新闻</li><li>招聘</li><li>广告</li></ul>
<div class="cont">
<div class="cont1">第一个选项卡的内容区域</div>
<div class="cont2">第二个选项卡的内容区域</div>
<div class="cont3">第三个选项卡的内容区域</div>
</div>
</div>
</body>
<script>
var ali = document.querySelectorAll(".box li");
var acont = document.querySelectorAll(".cont div");
for(var i=0;i<ali.length;i++){
ali[i].setAttribute("bianhao",i);
ali[i].onclick = function(){
for(var j=0;j<ali.length;j++){
ali[j].className = "";
acont[j].style.display = "none";
}
this.className = "active";
var dangQianLiDeBianHao = this.getAttribute("bianhao");
// console.log(dangQianLiDeBianHao);
acont[dangQianLiDeBianHao].style.display = "block";
}
}
</script>