鼠标放上去图片慢慢变大js 或变大

<!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>
     <title>鼠标放上去图片慢慢变大</title>
<script>
var oimage = null;
function zoom()
{
if (arguments.length > 0)
   oimage = arguments[0];
if(oimage.height<oimage.oldheight * 4 || oimage.width < oimage.oldwidth * 4)
{
   if(oimage.height < oimage.oldheight * 4) oimage.height+=10;
   if(oimage.width < oimage.oldwidth * 4) oimage.width+=10;
   z = setTimeout("zoom()",100);
}
else clearTimeout(z);
}

var oimage = null;
function zoom()
{
if (arguments.length > 0)
    oimage = arguments[0];
    oimage.height+=1;
    oimage.width+=1;

}

</script>

</head>
<body>
<img src="user/image/butongyi.gif"

oldwidth="100" oldheight="75" onmouseover="zoom(this)" onmouseout="clearTimeout(z);this.width = this.getAttribute(\'oldwidth\'); this.height = this.getAttribute(\'oldheight\');" ></a>
</body>
</html>