如何用JS判断一个网页中的图片是否下载结束

<img   src=http://expert.csdn.net/images/csdn.gif   border=0  
    onload="alert('图片加载完毕')"   onerror="alert('图片加载错误')">

 

 

 

 

 

 

 

<script>  
  var   oImage   =   new   Image();  
  oImage.src="xxxx.gif";  
  if(oImage.readyState   ==   "complete")  
  alert("complete.");  
  else   if(oImage.readyState   ==   "uninitialized")  
  alert("uninitialized");  
  </script>