JS+CSS实现淡入式焦点图片幻灯切换效果的方法

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：

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 class="list">
        <li class="current"><img src="/images/m01.jpg" width="320" height="240" /></li>
        <li><img src="/images/m02.jpg" width="320" height="240" /></li>
        <li><img src="/images/m03.jpg" width="320" height="240" /></li>
        <li><img src="/images/m04.jpg" width="320" height="240" /></li>
        <li><img src="/images/m05.jpg" width="320" height="240" /></li>
    </ul>
    <ul class="count">
        <li class="current">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。