物体不运动，不知道问题出在哪儿？报错信息是Uncaught TypeError: Cannot set property 'width' of undefined
<html>
<head>
<title>多物体运动</title>
<meta charset="utf-8">
<style type="text/css">
*{
margin: 0;
padding: 0;
}
ul,li{
list-style: none;
}
ul li{
width: 200px;
height:100px;
background: yellow;
margin-bottom: 20px;
}
</style>
<script type="text/javascript">
window.onload=function(){
var lis=document.getElementsByTagName('li');
for(var i=0;i<lis.length;i++){
lis[i].onmouseover=function(){
startMove(this,400);
}
lis[i].onmouseout=function(){
startMove(this,200);
}
}
}
var timer=null;
function startMove(obj,iTarget){
clearInterval(timer);
timer=setInterval(function(){
var speed=(iTarget-obj.offsetWidth)/10;
speed=speed>0?Math.ceil(speed):Math.floor(speed);
if (obj.offsetWidth==iTarget) {
clearInterval(timer);
}
else{
obj.sytle.width=obj.offsetWidth+speed+'px';
}
},50)
}
</script>
</head>
<body>
<ul>
<li></li>
<li></li>
<li></li>
</ul>
</body>
</html>
