tab切换案例

<!DOCTYPE html>
<html>
<head lang="en">
  <meta charset="UTF-8">
  <title></title>
  <style>
    * {
      margin: 0;
      padding: 0;
    }

    ul {
      list-style-type: none;
    }

    .box {
      width: 400px;
      height: 300px;
      border: 1px solid #ccc;
      margin: 100px auto;
      overflow: hidden;
    }

    .hd {
      height: 45px;
    }

    .hd span {
      display: inline-block;
      width: 90px;
      background-color: pink;
      line-height: 45px;
      text-align: center;
      cursor: pointer;
    }

    .hd span.current {
      background-color: purple;
    }

    .bd li {
      height: 255px;
      background-color: purple;
      display: none;
    }

    .bd li.current {
      display: block;
    }
  </style>

</head>
<body>
<div class="box" id="box">
  <div class="hd">
    <span class="current">体育</span>
    <span>娱乐</span>
    <span>新闻</span>
    <span>综合</span>
  </div>
  <div class="bd">
    <ul>
      <li class="current">我是体育模块</li>
      <li>我是娱乐模块</li>
      <li>我是新闻模块</li>
      <li>我是综合模块</li>
    </ul>
  </div>
</div>
<script>
  var box=document.getElementById("box");
  var hd=box.getElementsByTagName("div")[0];
  var bd=box.getElementsByTagName("div")[1];
  var list=bd.getElementsByTagName("li");
  var spans=hd.getElementsByTagName("span");
  for(var i=0;i<spans.length;i++){
  //在点击之前就把索引保存在span标签中
    spans[i].setAttribute("index",i);
    spans[i].onclick=function () {
      for(var j=0;j<spans.length;j++){
      //第一件事,所有的span的类样式全部移除
        spans[j].removeAttribute("class");
      }
      //第二件事,当前被点击的span应用类样式
      this.className="current";
      //span被点击的时候获取存储的索引值
      var num=this.getAttribute("index");
      //获取所有的li标签,每个li标签先全部隐藏
      for(var k=0;k<list.length;k++){
        list[k].removeAttribute("class");
      }
      //当前被点击的span对应的li标签显示
      list[num].className="current";
    };
  }
</script>
</body>
</html>