利用JavaScript实现上传图片预览

<script >
function showimage()
{ 
       //IMG1为图片控件或Div,File1为上传文件控件
document.getElementById("IMG1"). src = document.getElementById("File1").value;
}
</script >
控件中引用:
<input id="File1" runat="server" type="file"  onchange="showimage()"/>
IE7.0中由于不支持绝对路径,会出现图片显示错误.解决办法:
<script >
function showimage()
  {  
          document.getElementById("IMG1").filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src =
          document.getElementById ("File1").value;
  }
</script >
控件中引用:
<input id="File1" runat="server" type="file"  onchange="showimage()"/>
另外需在IMG或DIV样式中修改:
<div id="IMG1" style="filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);width:400px;height:200px;" runat="server" src="" /></div>