本文实例讲述了JS+CSS实现淡入式焦点图片幻灯切换效果的方法。分享给大家供大家参考。具体实现方法如下：
复制代码 代码如下:<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>一款JS+CSS淡入式焦点图片幻灯切换效果</title>
<style>
body,div,ul,li{margin:0;padding:0;}
ul{list-style-type:none;}
body{background:#000;text-align:center;font:12px/20px Arial;}
#box{position:relative;width:322px;height:172px;background:#fff;border-radius:5px;border:8px solid #fff;margin:10px auto;}
#box .list{position:relative;width:320px;height:240px;overflow:hidden;border:1px solid #ccc;}
#box .list li{position:absolute;top:0;left:0;width:320px;height:240px;opacity:0;filter:alpha(opacity=0);}
#box .list li.current{opacity:1;filter:alpha(opacity=100);}
#box .count{position:absolute;right:0;bottom:5px;}
#box .count li{color:#fff;float:left;width:20px;height:20px;cursor:pointer;margin-right:5px;overflow:hidden;background:#F90;opacity:0.7;filter:alpha(opacity=70);border-radius:20px;}
#box .count li.current{color:#fff;opacity:1;filter:alpha(opacity=100);font-weight:700;background:#f60;}
#tmp{width:100px;height:100px;background:red;position:absolute;}
</style>
<script type="text/javascript">
window.onload = function ()
{
var oBox = document.getElementById("box");
var aUl = document.getElementsByTagName("ul");
var aImg = aUl[0].getElementsByTagName("li");
var aNum = aUl[1].getElementsByTagName("li");
var timer = play = null;
var i = index = 0;
//切换按钮
for (i = 0; i < aNum.length; i++)
{
aNum[i].index = i;
aNum[i].onmouseover = function ()
{
show(this.index)
}
}
//鼠标划过关闭定时器
oBox.onmouseover = function ()
{
clearInterval(play)
};
//鼠标离开启动自动播放
oBox.onmouseout = function ()
{
autoPlay()
};
//自动播放函数
function autoPlay ()
{
play = setInterval(function () {
index++;
index >= aImg.length && (index = 0);
show(index);
},2000);
}
autoPlay();//应用图片切换 淡入淡出效果
function show (a)
{
index = a;
var alpha = 0;
for (i = 0; i < aNum.length; i++)aNum[i].className = "";
aNum[index].className = "current";
clearInterval(timer);
for (i = 0; i < aImg.length; i++)
{
aImg[i].style.opacity = 0;
aImg[i].style.filter = "alpha(opacity=0)";
}
timer = setInterval(function () {
alpha += 2;
alpha > 100 && (alpha =100);
aImg[index].style.opacity = alpha / 100;
aImg[index].style.filter = "alpha(opacity = " + alpha + ")";
alpha == 100 && clearInterval(timer)
},20);
}
};
</script>
</head>
<body>
<div id="box">
<ul>
<li><img src="http://www.jb51.netimages/m01.jpg" width="320" height="240" /></li>
<li><img src="http://www.jb51.netimages/m02.jpg" width="320" height="240" /></li>
<li><img src="http://www.jb51.netimages/m03.jpg" width="320" height="240" /></li>
<li><img src="http://www.jb51.netimages/m04.jpg" width="320" height="240" /></li>
<li><img src="http://www.jb51.netimages/m05.jpg" width="320" height="240" /></li>
</ul>
<ul>
<li>1</li>
<li>2</li>
<li>3</li>
<li>4</li>
<li>5</li>
</ul>
</div>
</body>
</html>
希望本文所述对大家的javascript程序设计有所帮助。