file upload using Uploadify

<link href="~/Uploadify/uploadify.css" rel="stylesheet" />
   <script src="~/Uploadify/jquery-1.4.1.js"></script>
   <script src="~/Uploadify/jquery.uploadify.v2.1.4.min.js"></script>
   <script src="~/Uploadify/swfobject.js"></script>

this is my controller Class

public ActionResult UploadAsync()
       {<<br mode="hold" />var model = new ListingModel();
List<string> imgNames;
if (Session["images"] == null)
{
imgNames = new List<string>();
}
else
{
imgNames = (List<string>)Session["images"];
}
string name = string.Empty;
if (Request.Files.Count > 0)
{
List<string> exts = new List<string>();
exts.Add(".gif");
exts.Add(".jpg");
exts.Add(".jpeg");
exts.Add(".bmp");
var file = Request.Files[0];
if (exts.Contains(System.IO.Path.GetExtension(file.FileName).ToLower()))
{
Random rnd = new Random();
name = rnd.Next(111, 9999).ToString() + "_" + System.IO.Path.GetFileName(file.FileName);
imgNames.Add(name);
string fullPath = Path.Combine(Server.MapPath("~/Content/AdImages"), name);
file.SaveAs(fullPath);
Session["images"] = imgNames;
}
else
{
name = "error";
}
// model.Images = imgNames;
}

return Json(name, JsonRequestBehavior.AllowGet); 
}



this is the javascript


<script type="text/javascript">
 $(document).ready(function () {
$('#File1').uploadify({
'uploader': '@Url.Content("~/Content/Uploadify/uploadify.swf")',
'script': '@Url.Content("~/Listing/UploadAsync/")',
'cancelImg': '@Url.Content("~/Content/Uploadify/cancel-uploading.png")',
'auto': true,
"buttonText": "Upload Image",
"scriptData": {},
"multi": true,
"onComplete": function (event, ID, fileObj, response, data) {
var json = jQuery.parseJSON(response);
if (json == 'error') {
$("#error").html('extension not supported');
}
else {
// $("#error").html('photo Uploaded');
$("#error").html('');
var imgs = document.getElementById('Images');
var thumbs = document.getElementById('thumbnails');
// imgs.value = json + '~' + imgs.value;
if (imgs.value != null)
imgs.value = imgs.value + '~' + json;
else
imgs.value = json;

var myTr = document.getElementById('trPreview');
var td0 = document.createElement('td');
td0.setAttribute("align", "center");
var img0 = document.createElement('img');
img0.setAttribute("id", json);
var src0 = '@Url.Content("~/Content/AdImages")' + '/' + json;
img0.setAttribute("src", src0);
img0.setAttribute("height", "100");
img0.setAttribute("width", "100");
td0.appendChild(img0);
var br0 = document.createElement('br');
td0.appendChild(br0);
myTr.appendChild(td0);
// var br = document.createElement('br');
// myTr.appendChild(br);
var btn = document.createElement('input');
btn.setAttribute("type", "button");
btn.setAttribute("value", "Remove");
btn.setAttribute("class", "t-button");
var btnId = "btn" + json + "";
btn.setAttribute("id", btnId);
var func = "removeimg('" + json + "','" + btnId + "')";
btn.setAttribute("onclick", func);
td0.appendChild(btn);
myTr.appendChild(td1);
thumbs.appendChild(tbl1);

}

}
});
if ($("#File1Queue") != null) {
$("#File1Queue").hide();
}
}); 
</script></string></string></string></string></string>