选项卡

代码
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin:0;
            padding:0;
        }
        ul, ul li{
            list-style:none;
        }
        #box{
            width:400px;
            height:300px;
            border:1px solid #000;
            margin:50px auto;
        }
        #list{
            display:flex;
            border-bottom:1px solid #000;
            box-sizing:border-box;
        }
        #list li{
            flex:1;
            text-align:center;
            border-right:1px solid #000;
            line-height:30px;
            box-sizing: border-box;
            cursor: pointer;
        }
        #list li:last-child{
            border:none;
        }
        .item{
            height:270px;
            display:none;
        }
        .active{
            background:pink;
            color:#fff;
        }
    </style>
</head>
<body>
    <div id="box">
        <!-- 选项卡按钮 -->
        <ul id="list">
            <li class="active">食品</li>
            <li>服饰</li>
            <li>家电</li>
            <li>运动</li>
        </ul>
        <!-- 板块 -->
        <div class="item" style="display:block">食品板块</div>
        <div class="item">服饰板块</div>
        <div class="item">家电板块</div>
        <div class="item">运动板块</div>
    </div>


    <script>
        var lis = document.getElementsByTagName('li');  // 4
        var items = document.getElementsByClassName('item'); // 4
        for(var i=0;i<lis.length;i++){
            // 给每个按钮添加索引
            lis[i].index = i;
            lis[i].onclick = function(){
                // 先把所有样式清空  先让所有板块隐藏
                for(var j=0;j<lis.length;j++){
                    lis[j].className = '';
                    items[j].style.display = 'none';
                }
                // 只给当前选中按钮添加样式
                this.className ='active';
                // 只给当前对应板块展示
                items[this.index].style.display = 'block';
            }
        }
    </script>
</body>
</html>
效果