<!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>透明度动画</title>
<link rel="stylesheet" href="reset.css">
<style type="text/css">
.odiv{200px; height:200px; background:#f00; position:relative; left:0px; top:100px;opacity:0.3; filter:alpha(opacity:30); float:left; margin:10px;}
</style>
</head>
<body>
<div id="odiv" class="odiv"></div>
</body>
</html>
<script language="javascript">
window.onload = function(){
var odiv = document.getElementsByTagName('div');
for(var i=0;i<odiv.length;i++)
{
odiv[i].onmouseover = function(){
startOP(this,100);
}
odiv[i].onmouseout = function(){
startOP(this,30);
}
odiv[i].timer = null;//事先定义
odiv[i].alpha = null;//事先定义
//这里发现一个问题，对象的动画属性可以不定义，但是透明度属性必须定义，否则报错
}
}
function startOP(obj,utarget){
clearInterval(obj.timer);//先关闭定时器
obj.timer = setInterval(function(){
var speed = 0;
if(obj.alpha>utarget){
speed = -10;
}
else{
speed = 10;
}
obj.alpha = obj.alpha+speed;
if(obj.alpha == utarget){
clearInterval(obj.timer);
}
obj.style.filter = 'alpha(opacity:'+obj.alpha+')';//基于IE的
obj.style.opacity = parseInt(obj.alpha)/100;
},300);
}
</script>