c#web控件FileUpload

Question

<script language="javascript" type="text/javascript">  
  function PreviewImg(imgFile)  
  {   
  var newPreview = document.getElementById("newPreview");  
  newPreview.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgFile.value;  
  newPreview.style.width = "80px";  
  newPreview.style.height = "60px";  
  }  
  </script>  
<asp:FileUpload ID="FileUpload1" runat="server" onchange="PreviewImg(this)" />  
<div id="newPreview"> </div>  
function $(o){return document.getElementById(o);}  
function CheckImg(o,img)  
{  
  if (!/\.((jpg)|(bmp)|(gif)|(png))$/ig.test(o.value))  
  {  
  alert('只能上传jpg,bmp,gif,png格式图片!');  
  o.outerHTML = o.outerHTML;  
  }  
  else  
  {  
  $(img).filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src=o.value;  
  }  
}  <asp:FileUpload ID="FileUpload1" runat="server" onchange="CheckImg(this, 'img');" />  
<div id="img" style="filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src= <%= pic%>,sizingMethod=scale);width:88px;height:113px;"> </div>  
public string pic="";