<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body {
            font-family: "Microsoft YaHei", serif;
        }

        body, dl, dd, p, h1, h2, h3, h4, h5, h6 {
            margin: 0;
        }

        ol, ul, li {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        img {
            border: none
        }
        #wrap{
            width: 1080px;
            height: 350px;
            margin: 50px auto;
        }
        #wrap .nav{
            position: relative;
            width: 100%;
            height: 40px;
            background-color: #f5f5f5;
            line-height: 40px;
        }
        #wrap .nav p{
            position: absolute;
            top: 0;
            left: 0;
            width: 130px;
            height: 40px;
            background-color: #000;
            color: #fff;
            text-align: center;
        }
        #wrap .nav p::after{
            content: "";
        }
        #wrap .nav ul{
            box-sizing: border-box;
            width: 100%;
            padding-left: 200px;
        }
        #wrap .nav ul li{
            position: relative;
            float: left;
            margin-right: 32px;
            cursor: pointer;
            transition: color .3s;
        }
        #wrap .nav ul li:hover{
            color: #db3a45;
        }
        #wrap .nav ul li::after{
            position: absolute;
            left: 0;
            right: 0;
            bottom: 0;
            margin: auto;
            content: "";
            width: 0;
            height: 2px;
            background-color: #db3a45;
            transition: width .3s;
        }
        #wrap .nav ul li.active::after{
            width: 100%;
        }
        #wrap .content{
            width: 100%;
            height: 255px;
            margin-top: 20px;
        }
        #wrap .content>ul{
            position: relative;
            width: 100%;
            height: 100%;
        }
        #wrap .content>ul li.first{
            display: none;
            overflow: hidden;
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
        }
        #wrap .content>ul li.first.show{
            display: block;
        }
        #wrap .content>ul li.first ul{
            width: 150%;
        }
        #wrap .content>ul li.first ul li{
            float: left;
            width: 340px;
            height: 255px;
            margin-right: 20px;
        }
    </style>
</head>
<body>
<div id="wrap">
    <div class="nav">
        <p class="title">独家精品策划</p>
        <ul>
            <li class="active">全部</li>
            <li>题目一</li>
            <li>题目二</li>
            <li>题目三</li>
            <li>题目四</li>
        </ul>
    </div>

    <div class="content">
        <ul>
            <li class="first show">
                <ul>
                    <!--<li class="second"><img src="img/1.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/2.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/3.png" alt=""></li>-->
                </ul>
            </li>
            <li class="first">
                <ul>
                    <!--<li class="second"><img src="img/1.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/2.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/3.png" alt=""></li>-->
                </ul>
            </li>
            <li class="first">
                <ul>
                    <!--<li class="second"><img src="img/1.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/2.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/3.png" alt=""></li>-->
                </ul>
            </li>
            <li class="first">
                <ul>
                    <!--<li class="second"><img src="img/1.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/2.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/3.png" alt=""></li>-->
                </ul>
            </li>
            <li class="first">
                <ul>
                    <!--<li class="second"><img src="img/1.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/1.jpg" alt=""></li>-->
                    <!--<li class="second"><img src="img/1.jpg" alt=""></li>-->
                </ul>
            </li>
        </ul>
    </div>
</div>
<script>

    (function (data) {

        let aNavLi = document.querySelectorAll("#wrap .nav ul li");
        let secondUl = document.querySelectorAll("#wrap .first ul");
        let index = 0;

        // 生成content的内容
        for (let i=0;i<data.length;i++) {
            let thisData = data[i];
            let {type, id, src} = thisData;
            // let type = thisData.type;
            // let id = thisData.id;
            // let src = thisData.src;
            // 从第二个类别开始往后边算，第一个全部没有东西
            secondUl[type+1].innerHTML += `<li class="second"><img src="${src}" alt=""></li>`;
            // 直接把前三张放到第一个类别
            if(i<3){
                secondUl[0].innerHTML += `<li class="second"><img src="${src}" alt=""></li>`
            }
            // switch(type){
            //     case 0:
            //         secondUl[1].innerHTML += `<li class="second"><img src="${src}" alt=""></li>`;
            //         break;
            //     case 1:
            //         secondUl[2].innerHTML += `<li class="second"><img src="${src}" alt=""></li>`;
            //         break;
            //     case 2:
            //         secondUl[3].innerHTML += `<li class="second"><img src="${src}" alt=""></li>`;
            //         break;
            //     case 3:
            //         secondUl[4].innerHTML += `<li class="second"><img src="${src}" alt=""></li>`;
            //         break;
            // }
        }
        let aFirstLi = document.querySelectorAll("#wrap .first");
        for (let i=0,len=aNavLi.length;i<len;i++){
            aNavLi[i].onmouseenter = function () {
                aNavLi[index].classList.remove("active");
                aFirstLi[index].classList.remove("show");
                index = i;
                aNavLi[index].classList.add("active");
                aFirstLi[index].classList.add("show");
            }
        }

    })(
        [
            {
                id:0,
                src:"img/1.jpg",
                type:0
            },
            {
                id:0,
                src:"img/2.jpg",
                type:0
            },
            {
                id:0,
                src:"img/3.png",
                type:0
            },
            {
                id:0,
                src:"img/3.png",
                type:1
            },
            {
                id:0,
                src:"img/2.jpg",
                type:1
            },
            {
                id:0,
                src:"img/1.jpg",
                type:1
            },
            {
                id:0,
                src:"img/1.jpg",
                type:2
            },
            {
                id:0,
                src:"img/2.jpg",
                type:2
            },
            {
                id:0,
                src:"img/3.png",
                type:2
            },
            {
                id:0,
                src:"img/1.jpg",
                type:3
            },
            {
                id:0,
                src:"img/2.jpg",
                type:3
            },
            {
                id:0,
                src:"img/3.png",
                type:3
            }
        ]
    );
</script>
</body>
</html>