圖片上傳預覽

 <td></td>
        <td colspan="4"> <asp:Image ID="Image1" runat="server" Width="94%"  Height="100PX"/></td>
        
                          
        <td style="width: 5px"></td>
       </tr>
       <tr height="25">
   <td></td>
        <td>圖片上傳：</td>
        <td colspan="3"><asp:FileUpload ID="FileUpload1" runat="server" Width="90%" TabIndex="66" />
        <script language="javascript" type="text/javascript">
        var showPic = function(obj){
                var fileURLSplit = obj.value.split(".");
                var fileExt=fileURLSplit[fileURLSplit.length-1].toLowerCase();
                if(fileExt=="jpg" || fileExt=="gif" ||fileExt=="bmp")
                {
                    var img = document.getElementById("Image1");
                    img.src = "file:///" + obj.value;
                    img.onerror = function(){
                        alert("請選擇一個圖片文件！");
                    }
                }
                else
                {
                    obj.value = " ";
                    alert("請選擇jpg、gif或bmp圖片文件");
                }
              
               
     
}
</script>

 

後臺代碼：

  FileUpload1.Attributes["onchange"] = "showPic(this)";