在浏览各大商城网站的时候，或者某些网站的首页，都会展示与本网站相关的一些实时切换的图片， 本文就给大家分享一个用jQuery实现图片自动切换的例子。
主页核心代码（Default.aspx）：
<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>jQuery实现图片切换</title> <script type="text/javascript" src="js/jquery-1.4.2.min.js"></script> <script type="text/javascript" src="js/tupianqiehuan.js"></script> <link rel="stylesheet" type="text/css" href="css/tupianqiehuan.css"> </head> <body> <p class="wrapper"> <h1>jquer实现图片切换</h1> <p id="focus"> <ul> <li><a href="#" target="_blank"><img src="images/01.jpg" alt="" /></a></li> <li><a href="#" target="_blank"><img src="images/02.jpg" alt="" /></a></li> <li><a href="#" target="_blank"><img src="images/03.jpg" alt="" /></a></li> <li><a href="#" target="_blank"><img src="images/04.jpg" alt="" /></a></li><span style="white-space:pre"> </ul> </p> </p> </body> </html>
CSS代码（tupianqiehuan.css）：
*{margin:0;padding:0;}
body{font-size:12px;color:#222;font-family:Verdana,Arial,Helvetica,sans-serif;background:#f0f0f0;}
.clearfix:after{content: ".";display: block;height: 0;clear: both;visibility: hidden;}
.clearfix{zoom:1;}
ul,li{list-style:none;}
img{border:0;}
.wrapper{width:800px;margin:0 auto;padding-bottom:50px;}
h1{height:50px;line-height:50px;font-size:22px;font-weight:normal;font-family:"Microsoft YaHei",SimHei;margin-bottom:20px;}
/* focus */
#focus{width:800px;height:280px;overflow:hidden;position:relative;}
#focus ul{height:380px;position:absolute;}
#focus ul li{float:left;width:800px;height:280px;overflow:hidden;position:relative;background:#000;}
#focus ul li p{position:absolute;overflow:hidden;}
#focus .btnBg{position:absolute;width:800px;height:20px;left:0;bottom:0;background:#000;}
#focus .btn{position:absolute;width:780px;height:10px;padding:5px 10px;right:0;bottom:0;text-align:right;}
#focus .btn span{display:inline-block;_display:inline;_zoom:1;width:25px;height:10px;_font-size:0;margin-left:5px;cursor:pointer;background:#fff;}
#focus .btn span.on{background:#fff;}
#focus .preNext{width:45px;height:100px;position:absolute;top:90px;background:url(http://sandbox.runjs.cn/uploads/rs/475/xaqlrnnr/sprite.png) no-repeat 0 0;cursor:pointer;}
#focus .pre{left:0;}
#focus .next{right:0;background-position:right top;}JS代码（tupianqiehuan.js）：