使用运动框架为什么实现不了borderWidth 的变化功能，请高手指点。代码如下：-慕课网

使用运动框架为什么实现不了borderWidth 的变化功能，请高手指点。代码如下：

来源：9-18 浏览器窗口可视区域大小

慕虎5948952

2016-08-18 15:37

<!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=gb2312" />
<title>边框运动</title>
<style>
div{width:100px; height:100px; margin:20px; float:left; background:yellow; border:2px solid green;
    filter:alpha(opacity=30);
      opacity:0.3;
}
</style>
<script>
function getStyle(obj,name){
   if(obj.currentStyle){
       return obj.currentStyle[name]}else{
           return getComputedStyle(obj,false)[name];
           }

   }
window.onload=function(){
   var aDiv1=document.getElementById('div1');
;
var oTxt=document.getElementById('txt');
aDiv1.onmouseover=function(){
   startMove(this,'borderWidth',100);
   }
aDiv1.onmouseout=function(){
   startMove(this,'borderWidth',30);
   }
/*aDiv1.onmouseover=function(){
   startMove(this,'width',400);
   }
aDiv1.onmouseout=function(){
   startMove(this,'width',100);
   }*/

}

function startMove(obj,attr,iTarget){

   clearInterval(obj.timer);
   obj.timer=setInterval(function(){
               var cur=parseInt(getStyle(obj,attr))
       if(attr=='opacity'){
           cur=parseFloat(getStyle(obj,attr))*100;
           }else{
               cur=parseInt(getStyle(obj,attr));

               }

       var speed=(iTarget-cur)/4;
       speed=speed>0?Math.ceil(speed):Math.floor(speed);
if(cur==iTarget){
   clearInterval(obj.timer);}
   else{
       if(attr=='opacity'){
       obj.style.filter='alpha(opacity:'+cur+speed+')';
       obj.style.opacity=(cur+speed)/100;
       var oTxt=document.getElementById('txt');
       oTxt.value=   obj.style.opacity;


           }else{
   obj.style[attr]=cur+speed+'px';
   var oTxt=document.getElementById('txt');
   oTxt.value=   cur+speed;}
       }
       },30)
   }

</script>

</head>

<body>
<input id='txt' type="text" />
<div id='div1'>边框运动</div>
</body>
</html>