轮播图实现技巧-优快云博客

本文链接：https://blog.youkuaiyun.com/yinviolet/article/details/100556369
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>轮播图</title>
    <style>
        *{
            padding: 0;
            margin: 0;
        }
        .box{
            position: relative;
            width: 392px;
            height:300px;
            border:1px solid #333;
            margin: 150px auto;
            overflow: hidden;
            position: relative;
        }
        ul.ul{
            position: absolute;
            left: 0;
            top: 0;
            width:2744px;
            height: 300px;
        }
        li{
            list-style: none;
            float: left;
        }
        li img{
            width:392px;
            height: 300px;
        }
        .btns{
            width: 392px;
            height: 50px;
            position: absolute;
            top: 50%;
            margin-top: -25px;
        }
        .btns div{
            width: 30px;
            height: 100px;
            line-height: 50px;
            color: #333;
            text-align: center;
        }
        .leftBtn{
            float: left;
        }
        .rightBtn{
            float: right;
        }
        .clear:after{
            content: "";
            display: block;
            clear: both;
        }
        ul.cirs{
            position: absolute;
            bottom: 0;
            left:0;
            right: 0;
            height: 30px;
            display: flex;
            justify-content: center;
            align-items: center;
        }
        .cirs li{
            float: left;
            width: 10px;
            height: 10px;
            border-radius: 50%;
            margin: auto 10px;
            border: 1px solid #ff9;
        }
        .active{
            background: #99f;
        }
    </style>
</head>
<body>
    <div class="box clear">
        <ul class="clear ul">
            <li><img src="imags/t1.jpg"/></li>
            <li><img src="imags/t2.jpg"/></li>
            <li><img src="imags/t3.jpg"/></li>
            <li><img src="imags/t4.jpg"/></li>
            <li><img src="imags/t5.jpg"/></li>
            <li><img src="imags/t6.jpg"/></li>
            <li><img src="imags/t1.jpg"/></li>
        </ul>
        <ul class="cirs clear">
            <li class="active"></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
        </ul>
        <div class="btns clear">
            <div id="leftBtn" class="leftBtn">&lt;</div>
            <div id="rightBtn" class="rightBtn">&gt;</div>
        </div>
    </div>
    <script src="./value.js"></script>
    <script>
        // 获取元素
        var leftBtn = document.getElementById("leftBtn");
        var rightBtn = document.getElementById("rightBtn");
        var ul = document.getElementsByTagName("ul")[0];
        var box = document.getElementsByTagName("div")[0];
        var lis = document.querySelectorAll(".cirs li");
        // 定义一个变量，用来保存获取到的width
        var indanse = box.clientWidth;
        // 定义一个信号量
        var index = 0;
        // 先给右边的按钮设置点击事件
        rightBtn.onclick = function(){
            index++;
            move(ul,{left:-index * indanse},1000,function(){
                if(index === 6){
                        index = 0;
                        ul.style.left = 0;
                    }
                colorCirs();
                });
                
            }
        // 判断index，使其index能够在到达第五个之后能够跳转到第一个图片
        leftBtn.onclick = function(){
            index--;
            if(index < 0){
                index = 6;
                ul.style.left = -index * indanse + "px";
                index--;
            }
            move(ul,{left:-index * indanse},1000,function(){
                colorCirs();
            });
        }
    
        //利用for循环，给每一个li设置点击事件
        for(var i = 0;i < lis.length;i++){
            lis[i].onclick = function(){
                index = i;
                move(ul,{left:-index * indanse},1000,function(){
                    // 改变颜色，定义一个函数用于改变其颜色,并移除className
                    colorCirs();
                })
            }
        }
        function colorCirs(){
            for(let i = 0; i < lis.length;i++){
                lis[i].className = "";
            }
            lis[index].className = "active";
        }
    </script>
</body>