【前端丨学习笔记】js实现轮播图

Amy · 发表于 2019-1-5 14:25:38

【前端丨学习笔记】js实现轮播图

【零基础学习web前端】教程目录导航

http://www.sufeinet.com/thread-24027-1-1.html

实现轮播图原理是将一些图片在一行中平铺，然后计算偏移量再利用定时器实现定时轮播。

[HTML] 纯文本查看 复制代码

<html>
<head>
    <meta charset="UTF-8">
    <title>轮播图</title>
    <style>
        * {
            margin:0;
            padding:0;
        }
        a{
            text-decoration: none;
        }
        .container {
            position: relative;
            width: 600px;
            height: 400px;
            margin:100px auto 0 auto;
            box-shadow: 0 0 5px green;
            overflow: hidden;
        }
        .container .wrap {
            position: absolute;
            width: 4200px;
            height: 400px;
            z-index: 1;
        }
        .container .wrap img {
            float: left;
            width: 600px;
            height: 400px;
        }
        .container .buttons {
            position: absolute;
            right: 5px;
            bottom:40px;
            width: 150px;
            height: 10px;
            z-index: 2;
        }
        .container .buttons span {
            margin-left: 5px;
            display: inline-block;
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background-color: #fff;
            text-align: center;
            color:black;
            cursor: pointer;
        }
        .container .buttons span.on{
            background-color: green;
            color: #fff;
        }
        .container .arrow {
            position: absolute;
            top: 35%;
            color: green;
            padding:0px 14px;
            border-radius: 50%;
            font-size: 50px;
            z-index: 2;
            display: none;
        }
        .container .arrow_left {
            left: 10px;
        }
        .container .arrow_right {
            right: 10px;
        }
        .container:hover .arrow {
            display: block;
        }
        .container .arrow:hover {
            background-color: rgba(0,0,0,0.2);
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="wrap" style="left: -600px;">
            <img src="./img/5.jpg" alt="">
            <img src="./img/1.jpg" alt="">
            <img src="./img/2.jpg" alt="">
            <img src="./img/3.jpg" alt="">
            <img src="./img/4.jpg" alt="">
            <img src="./img/5.jpg" alt="">
            <img src="./img/1.jpg" alt="">
        </div>
        <div class="buttons">
            <span class="on">1</span>
            <span>2</span>
            <span>3</span>
            <span>4</span>
            <span>5</span>
        </div>
        <a href="javascript:;" class="arrow arrow_left"><</a>
        <a href="javascript:;" class="arrow arrow_right">></a>
    </div>
    <script>
        var wrap = document.querySelector(".wrap");
        var next = document.querySelector(".arrow_right");
        var prev = document.querySelector(".arrow_left");
        next.onclick = function () {
            next_pic();
        }
        prev.onclick = function () {
            prev_pic();
        }
        function next_pic () {
            index++;
            if(index > 4){
                index = 0;
            }
            showCurrentDot();
            var newLeft;
            if(wrap.style.left === "-3600px"){
                newLeft = -1200;
            }else{
                newLeft = parseInt(wrap.style.left)-600;
            }
            wrap.style.left = newLeft + "px";
        }
        function prev_pic () {
            index--;
            if(index < 0){
                index = 4;
            }
            showCurrentDot();
            var newLeft;
            if(wrap.style.left === "0px"){
                newLeft = -2400;
            }else{
                newLeft = parseInt(wrap.style.left)+600;
            }
            wrap.style.left = newLeft + "px";
        }
        var timer = null;
        function autoPlay () {
            timer = setInterval(function () {
                next_pic();
            },2000);
        }
        autoPlay();

        var container = document.querySelector(".container");
        container.onmouseenter = function () {
            clearInterval(timer);
        }
        container.onmouseleave = function () {
            autoPlay();    
        }

        var index = 0;
        var dots = document.getElementsByTagName("span");
        function showCurrentDot () {
            for(var i = 0, len = dots.length; i < len; i++){
                dots[i].className = "";
            }
            dots[index].className = "on";
        }

        for (var i = 0, len = dots.length; i < len; i++){
            (function(i){
                dots[i].onclick = function () {
                    var dis = index - i;
                    if(index == 4 && parseInt(wrap.style.left)!==-3000){
                        dis = dis - 5;     
                    }
                    //和使用prev和next相同，在最开始的照片5和最终的照片1在使用时会出现问题，导致符号和位数的出错，做相应地处理即可
                    if(index == 0 && parseInt(wrap.style.left)!== -600){
                        dis = 5 + dis;
                    }
                    wrap.style.left = (parseInt(wrap.style.left) +  dis * 600)+"px";
                    index = i;
                    showCurrentDot();
                }
            })(i);            
        }
    </script>
</body>
</html>

运行后效果：

liu · 发表于 2019-1-5 14:42:50

强烈支持楼主ing……

站长苏飞 · 发表于 2019-1-5 14:49:58

我只是路过打酱油的。

竹林风 · 发表于 2019-1-5 14:56:47

我只是路过打酱油的。

范范 · 发表于 2019-1-5 20:48:31

无回帖，不论坛，这才是人道。

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[零基础学习web前端] 【前端丨学习笔记】js实现轮播图

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