JavaScript实现轮播图效果
要求:
- 鼠标经过轮播图模块,左右按钮显示,离开隐藏左右按钮
- 点击右侧按钮一次,图片往左播放一张,以此类推,左侧按钮同理
- 图片播放的同时,下面小圆圈模块跟随一起变化
- 点击小圆圈,可以播放相应图片
- 鼠标不经过轮播图,轮播图也会自动播放图片
- 鼠标经过,轮播图模块,自动播放停止
代码实现:
autoPlay.html(复制并保存为html文件,打开即可见效果):
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <link rel="stylesheet" href="https://blog-static.cnblogs.com/files/jacklzx/autoPlay.css" rel="external nofollow" > <script src="https://blog-static.cnblogs.com/files/jacklzx/animate.js"></script> <script src="https://blog-static.cnblogs.com/files/jacklzx/autoPlay.js"></script> </head> <body> <div class="focus"> <!-- 左侧按钮 --> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="arrow-l"><</a> <!-- 右侧按钮 --> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="arrow-r">></a> <!-- 滚动区域 --> <ul> <li> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ><img src="https://s1.ax1x.com/2020/10/12/0W1wlt.jpg" alt=""></a> </li> <li> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ><img src="https://s1.ax1x.com/2020/10/12/0W3nHS.jpg" alt=""></a> </li> <li> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ><img src="https://s1.ax1x.com/2020/10/12/0Wtrmq.jpg" alt=""></a> </li> <li> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ><img src="https://s1.ax1x.com/2020/10/12/0W1NYd.jpg" alt=""></a> </li> </ul> <!-- 小圆圈 --> <ol class="circle"> </ol> </div> </body> </html>
autoPlay.css:
li { list-style: none; } a { text-decoration: none; } * { margin: 0; padding: 0; } body { background-color: #00e1ff; } .focus { overflow: hidden; position: relative; width: 721px; height: 455px; margin: 100px auto; box-shadow: 10px 10px 20px rgba(0, 0, 0, 0.6); border-radius: 40px; } .focus ul { position: absolute; top: 0; left: 0; width: 600%; } .focus ul li { float: left; } .arrow-l { display: none; position: absolute; top: 50%; left: -12px; margin-top: -20px; width: 40px; height: 40px; background: rgba(0, 0, 0, .3); text-align: center; line-height: 40px; color: #fff; font-size: 18px; border-radius: 0 50% 50% 0; z-index: 999; } .arrow-r { display: none; position: absolute; top: 50%; right: -12px; margin-top: -20px; width: 40px; height: 40px; background: rgba(0, 0, 0, .3); text-align: center; line-height: 40px; color: #fff; font-size: 18px; border-radius: 50% 0 0 50%; z-index: 999; } .circle { position: absolute; bottom: 10px; left: 50%; transform: translateX(-50%); } .circle li { float: left; width: 12px; height: 12px; border: 2px solid rgba(255, 255, 255, .5); margin: 0 4px; border-radius: 50%; cursor: pointer; } .current { background-color: #fff; box-shadow: 0 0 10px #fff; }
autoPlay.js:
window.addEventListener('load', function() { // 获取元素 var arrow_l = document.querySelector('.arrow-l'); var arrow_r = document.querySelector('.arrow-r'); var focus = document.querySelector('.focus'); var focusWidth = focus.offsetWidth; // 自定义动画函数animate的参数,表示动画间隔 var step = 5; // 鼠标经过focus 就显示左右按钮,停止计时器 focus.addEventListener('mouseenter', function() { arrow_l.style.display = 'block'; arrow_r.style.display = 'block'; clearInterval(timer); timer = null; // 清空计时器 }); // 鼠标离开focus 就隐藏左右按钮,调用定时器 focus.addEventListener('mouseleave', function() { arrow_l.style.display = 'none'; arrow_r.style.display = 'none'; timer = setInterval(function() { // 手动调用点击事件 arrow_r.click(); }, 2000); }); var ul = focus.querySelector('ul'); var ol = focus.querySelector('.circle'); for (var i = 0; i < ul.children.length; i++) { // 创建 li var li = document.createElement('li'); // 设置自定义属性,记录小圆圈索引号 li.setAttribute('index', i); // li插入ol ol.appendChild(li); // 小圈圈排他思想 生成圈圈同时 直接绑定事件 li.addEventListener('click', function() { for (var i = 0; i < ol.children.length; i++) { ol.children[i].className = ''; } this.className = 'current'; // 点击小圈圈,移动图片,移动的是ul // 点击li,拿到当前的索引号 var index = this.getAttribute('index'); // 当点击了li之后,就要把index给num,实现同步 num = index; // 当点击了li之后,就要把index给circle,实现同步 circle = index; animate(ul, -index * focusWidth, step); }); } // ol里第一个li的类名设置为current ol.children[0].className = 'current'; var num = 0; // circle控制小圆圈的播放 var circle = 0; // 克隆第一章图片li,放到ul最后面 // 要在生成小圆圈之后克隆 var first = ul.children[0].cloneNode(true); ul.appendChild(first); // 点击右侧按钮,图片滚动 arrow_r.addEventListener('click', function() { // 如果到了最后一张图片,ul要快速复原:left改为0 if (num == ul.children.length - 1) { ul.style.left = 0; num = 0; } num++; animate(ul, -num * focusWidth, step); // circle控制小圆圈的播放 circle++; circle = circle == ol.children.length ? 0 : circle; circleChange(); }); // 点击左侧按钮,图片滚动 arrow_l.addEventListener('click', function() { if (num == 0) { num = ul.children.length - 1; ul.style.left = -num * focusWidth + 'px'; } num--; animate(ul, -num * focusWidth, step); // circle控制小圆圈的播放 circle--; circle = circle < 0 ? (ol.children.length - 1) : circle; circleChange(); }); // 小圈圈改变样式 function circleChange() { // 排他其他 for (var i = 0; i < ol.children.length; i++) { ol.children[i].className = ''; } // 留下自己 ol.children[circle].className = 'current'; } // 自动播放功能 var timer = setInterval(function() { // 手动调用点击事件 arrow_r.click(); }, 2000); });
animate.js:
function animate(obj, target, time, callback) { // 先清除以前的定时器,只保留当前的一个定时器执行 clearInterval(obj.timer); obj.timer = setInterval(function() { // 步长值写到定时器的里面,并设置为整数 var step = (target - obj.offsetLeft) / 10; step = step > 0 ? Math.ceil(step) : Math.floor(step); if (obj.offsetLeft == target) { clearInterval(obj.timer); // 回调函数写到定时器结束里面 callback && callback(); } obj.style.left = obj.offsetLeft + step + 'px'; }, time); }
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