下面看下js轮播图的实现代码，具体代码如下所示：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title></title> <style type="text/css"> * { padding: 0; margin: 0; list-style: none; border: 0; } .all { width: 500px; height: 200px; padding: 7px; border: 1px solid #ccc; margin: 100px auto; position: relative; } .screen { width: 500px; height: 200px; overflow: hidden; position: relative; } .screen li { width: 500px; height: 200px; overflow: hidden; float: left; } .screen ul { position: absolute; left: 0; top: 0px; width: 3000px; } .all ol { position: absolute; right: 10px; bottom: 10px; line-height: 20px; text-align: center; } .all ol li { float: left; width: 20px; height: 20px; background: #fff; border: 1px solid #ccc; margin-left: 10px; cursor: pointer; } .all ol li.current { background: yellow; } #arr { display: none; } #arr span { width: 40px; height: 40px; position: absolute; left: 5px; top: 50%; margin-top: -20px; background: #000; cursor: pointer; line-height: 40px; text-align: center; font-weight: bold; font-family: '黑体'; font-size: 30px; color: #fff; opacity: 0.3; border: 1px solid #fff; } #arr #right { right: 5px; left: auto; } </style> </head> <body> <div> <div> <ul> <li><img src="https://www.jb51.net/images/1.jpg"/></li> <li><img src="https://www.jb51.net/images/2.jpg"/></li> <li><img src="https://www.jb51.net/images/3.jpg"/></li> <li><img src="https://www.jb51.net/images/4.jpg"/></li> <li><img src="https://www.jb51.net/images/5.jpg"/></li> </ul> <ol> </ol> </div> <div><span><</span><span>></span></div> </div> <script> function $(element) { return document.getElementById(element); } var box = $("box"); var screen = box.children[0]; var ul = screen.children[0]; var ulLis = ul.children; var ol = screen.children[1]; var arr = $("arr"); var left = $("left"); var right = $("right"); //动态创建小图标 for (var i = 0; i < ulLis.length; i++) { var li = document.createElement("li"); li.innerHTML = i + 1; ol.appendChild(li); } //设置这些个小图标 var olLis = ol.children; var imgWidth = screen.offsetWidth; for (var j = 0; j < olLis.length; j++) { olLis[j].index = j; olLis[j].onmouseover = function () { //排他思想 for (var i = 0; i < olLis.length; i++) { olLis[i].className = ""; } this.className = "current"; var target = -imgWidth * this.index; cutton(ul, target, 20); //为了让点击事件和小面的小图标能够一一对应，设置他们的索引值相同 pic = square = this.index; } } //给小图标设置一个初始样式 ol.children[0].className = "current"; //给ul追加一张图 ul.appendChild(ul.children[0].cloneNode(true)); //设置箭头的显示与隐藏 box.onmouseover = function () { arr.style.display = "block"; //鼠标放上去的时候，不再自动滚动 clearInterval(timer); } box.onmouseout = function () { arr.style.display = "none"; //鼠标离开的时候，继续自动滚动 timer = setInterval(playNext, 1000); } //设置点击左右小箭头的事件且要求小图标要跟着变化 //1.设置点击右侧箭头 var pic = 0;//记录当前为第几项用 var square = 0;//记录小图标的索引值 /* right.onclick = function () {//存在的问题是当移动到最后一张的时候，无法跳转到第一张 pic++; var target = -pic * imgWidth; cutton(ul, target, 20); }*/ //方法改进 /*right.onclick = function () { //先对pic做一个判断，当pic的值为5的时候，实现一个跳转 if (pic == ulLis.length - 1) { ul.style.left = 0; pic = 0; } pic++; var target = -pic * imgWidth; cutton(ul, target, 20); if (square == olLis.length - 1) { square = -1;//下面会加一，就变成了0 } square++; //排他思想 for (var i = 0; i < olLis.length; i++) { olLis[i].className = ""; } olLis[square].className = "current"; }*/ //使用封装函数 right.onclick = function () { playNext(); } //2.设置点击左侧箭头 left.onclick = function () {//要判断一下当pic为零时的情况 if (pic == 0) { ul.style.left = -imgWidth * (ulLis.length - 1) + "px";//要记得加单位 pic = ulLis.length - 1;//给pic重新赋一个值 } pic--; var target = -pic * imgWidth; cutton(ul, target, 20); //设置小图标样式 if (square == 0) { square = olLis.length; } square--; for (var i = 0; i < olLis.length; i++) { olLis[i].className = ""; } olLis[square].className = "current"; } //设置自动滚动 //1.封装点击右侧小箭头事件 function playNext() { //先对pic做一个判断，当pic的值为5的时候，实现一个跳转 if (pic == ulLis.length - 1) { ul.style.left = 0; pic = 0; } pic++; var target = -pic * imgWidth; cutton(ul, target, 20); if (square == olLis.length - 1) { square = -1;//下面会加一，就变成了0 } square++; //排他思想 for (var i = 0; i < olLis.length; i++) { olLis[i].className = ""; } olLis[square].className = "current"; } //2.调用这个封装的函数，并且设置一个间歇性计时器 var timer = null; timer = setInterval(playNext, 1000); //封装函数 function cutton(obj, target, stp) { clearInterval(obj.timer); obj.timer = setInterval(function () { var step = stp; step = obj.offsetLeft > target ? -step : step; if (Math.abs(obj.offsetLeft - target) >= Math.abs(step)) { obj.style.left = obj.offsetLeft + step + "px"; } else { obj.style.left = target + "px"; clearInterval(obj.timer); } }, 15) } </script> </body> </html>
补充：原生javascript实现banner图自动轮播切换