图片轮番显示效果

下面为效果显示

脚本说明:
把如下代码加入<body>区域中
<style type="text/css">
#img1 {position:absolute; width:300px; height:100px; left:220px; top:125px; z-index:1; visibility:hidden;}
#img2 {position:absolute; width:300px; height:100px; left:220px; top:125px; z-index:2}
</style>

<SCRIPT LANGUAGE="JavaScript">
<!-- Begin
var ie5=(document.getElementById && document.all);
var ns6=(document.getElementById && !document.all);

nPlus = 5   //the % of fading for each step
speed = 50  //the speed

// You don't have to edit below this line
nOpac = 100
function FadeImg(){
    if(document.getElementById){
        document.getElementById('img1').style.visibility="visible";
        imgs = document.getElementById('img2');
	opacity = nOpac+nPlus;
	nOpac = opacity;
	setTimeout('FadeImg()',speed);
    if(opacity>100 || opacity<0){
        nPlus=-nPlus;
    }
    if(ie5){
        imgs.style.filter="alpha(opacity=0)";
	imgs.filters.alpha.opacity = opacity;
    }
    if(ns6){
        imgs.style.MozOpacity = 0 + '%';
	imgs.style.MozOpacity = opacity + '%';
    }
  }
}
onload=FadeImg;
//  End -->
</script>
<div id="img1">
  <img src="img1.gif" border=0 width=300 height=100>
</div>
<div id="img2">
  <img src="img2.gif" border=0 width=300 height=100>
</div>