用html+css+js实现的一个简单的图片切换特效

<div class="wrapper">
<div id="focus">
<ul>
<li><a href="http://www.lanrentuku.com/" target="_blank"><img" width=100% src="img/01.jpg" alt="QQ商城焦点图效果下载" /></a></li>
<li><a href="http://www.lanrentuku.com/" target="_blank"><img" width=100% src="img/02.jpg" alt="QQ商城焦点图效果教程" /></a></li>
<li><a href="http://www.lanrentuku.com/" target="_blank"><img" width=100% src="img/03.jpg" alt="jquery商城焦点图效果" /></a></li>
<li><a href="http://www.lanrentuku.com/" target="_blank"><img" width=100% src="img/04.jpg" alt="jquery商城焦点图代码" /></a></li>
<li><a href="http://www.lanrentuku.com/" target="_blank"><img" width=100% src="img/05.jpg" alt="jquery商城焦点图源码" /></a></li>
</ul>
</div>

</div><!-- wrapper end -->
</body>

<style type="text/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;}

/* qqshop 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 div {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(img/sprite.png) no-repeat 0 0; cursor:pointer;}
#focus .pre {left:0;}
#focus .next {right:0; background-position:right top;}
</style>

$(function() {
var sWidth = $("#focus").width(); //获取焦点图的宽度（显示面积）
var len = $("#focus ul li").length; //获取焦点图个数
var index = 0;
var picTimer;

//以下代码添加数字按钮和按钮后的半透明条，还有上一页、下一页两个按钮
var btn = "<div class='btnBg'></div><div class='btn'>";
for(var i=0; i < len; i++) {
btn += "<span></span>";
}
btn += "</div><div class='preNext pre'></div><div class='preNext next'></div>";
$("#focus").append(btn);
$("#focus .btnBg").css("opacity",0.5);

//为小按钮添加鼠标滑入事件，以显示相应的内容
$("#focus .btn span").css("opacity",0.4).mouseenter(function() {
index = $("#focus .btn span").index(this);
showPics(index);
}).eq(0).trigger("mouseenter");

//上一页、下一页按钮透明度处理
$("#focus .preNext").css("opacity",0.2).hover(function() {
$(this).stop(true,false).animate({"opacity":"0.5"},300);
},function() {
$(this).stop(true,false).animate({"opacity":"0.2"},300);
});

//上一页按钮
$("#focus .pre").click(function() {
index -= 1;
if(index == -1) {index = len - 1;}
showPics(index);
});

//下一页按钮
$("#focus .next").click(function() {
index += 1;
if(index == len) {index = 0;}
showPics(index);
});

//本例为左右滚动，即所有li元素都是在同一排向左浮动，所以这里需要计算出外围ul元素的宽度
$("#focus ul").css("width",sWidth * (len));

//鼠标滑上焦点图时停止自动播放，滑出时开始自动播放
$("#focus").hover(function() {
clearInterval(picTimer);
},function() {
picTimer = setInterval(function() {
showPics(index);
index++;
if(index == len) {index = 0;}
},4000); //此4000代表自动播放的间隔，单位：毫秒
}).trigger("mouseleave");

//显示图片函数，根据接收的index值显示相应的内容
function showPics(index) { //普通切换
var nowLeft = -index*sWidth; //根据index值计算ul元素的left值
$("#focus ul").stop(true,false).animate({"left":nowLeft},300); //通过animate()调整ul元素滚动到计算出的position
//$("#focus .btn span").removeClass("on").eq(index).addClass("on"); //为当前的按钮切换到选中的效果
$("#focus .btn span").stop(true,false).animate({"opacity":"0.4"},300).eq(index).stop(true,false).animate({"opacity":"1"},300); //为当前的按钮切换到选中的效果
}
});