无法执行链式运动，还报错了
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>多物体运动</title>
<style type="text/css">
*{margin: 0;padding: 0;}
li{list-style:none;width: 200px;height: 100px;background: black;margin-bottom: 20px;border: 1px solid #f00;
filter: alpha(opacity:30);opacity: 0.3;}
</style>
<script type="text/javascript">
window.onload=function(){
var li=document.getElementsByTagName('li');
for(var i=0;i<li.length;i++){
li[i].timer=null;
li[i].onmouseover=function(){
startMove(this,{width:400,height:200},function(){
startMove(this,{opacity:100});
});
}
li[i].onmouseout=function(){
startMove(this,{width:200,height:100,opacity:30});
}
}
function getStyle (obj,attr){ return obj.currentStyle?obj.currentStyle[attr] : getComputedStyle( obj )[attr]; }
function startMove(obj,json,fn){
clearInterval(obj.timer);
obj.timer=setInterval(function(){
var iFlag=true;//假设所有运动都到达目标
for(var attr in json){
//1.取当前值
var icur=0;
attr=='opacity'? icur=Math.round(parseFloat(getStyle(obj,attr))*100) : icur=parseInt(getStyle(obj,attr));
//2.计算速度
var speed=(json[attr]-icur)/10;
speed=speed>0?Math.ceil(speed):Math.floor(speed);
//3.检测停止
if(icur!=json[attr]){
iFlag=false;
}
if(attr=='opacity'){
obj.style.filter='alpha(opacity:'+icur+speed+')';
obj.style.opacity=(icur+speed)/100;
}else{
obj.style[attr]=icur+speed+'px';
}
}
if(iFlag){
clearInterval(obj.timer);
fn && fn();
}
},30)
}
}
</script>
</head>
<body>
<ul>
<li></li>
<li></li>
<li></li>
</ul>
</body>
</html>
哪位兄弟帮我看下
