<!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>无标题文档</title>
<style type="text/css">
#boss{
width:300px;
height:300px;
background:#CF3;
opacity:0.3}
</style>
<script type="text/javascript">
window.onload=function(){
var boss=document.getElementById('boss'),timer=null,alpha=30;
boss.onmouseover=function()
{
opa(100);
}
boss.onmouseout=function()
{
opa(30);
}
function opa(itarget){
clearInterval(timer);
timer=setInterval(function(){
var speed=0;
if(alpha>itarget)
speed=-10;
else
speed=10;
if(boss.style.opacity==itarget)
clearInterval(timer);
else{
alpha+=speed;
boss.style.filter='alpha(opactiy:'+alpha+');'
boss.style.opacity=alpha/100;
}
},30)
}
}
</script>
</head>
<body>
<div id="boss">
</div>
</body>
</html>
我的代码，和老师讲的几乎一样啊，为什么透明度在1和0.3左右的一直在变
if(boss.style.opacity==itarget)
clearInterval(timer);
这块没能清除 计时器，
boss.style.opacity 他算出的是浮点数就是0.3不可能等于itarget30。把他换成alpha 就好了。