求助！！！
<!DOCTYPE html>
<html>
<head>
<title></title>
<style type="text/css">
#div1{
background: red;
width: 100px;
height:100px;
border:2px solid gray;
}
</style>
<script type="text/javascript">
window.onload=function(){
var oDiv=document.getElementById("div1");
oDiv.onmouseover=function(){
startMove(0);
}
}
function startMove(iTarget){
var timer;
clearInterval(timer);
var oDiv=document.getElementById("div1");
timer=setInterval(function(){
oDiv.style.width=parseInt(getStyle(oDiv,width))-1+'px';
},50);
}
function getStyle(obj,attr){
if(obj.currentStyle){
return obj.currentStyle[attr];
}
else{
return getComputedStyle(obj,false)[attr];
}
}
</script>
</head>
<body>
<div id="div1"></div>
</body>
</html>为什么会显示
width is not defined
