ASP.NET

Like in the below function I need to set the value of the file upload to "No file chosen", if I try to set it up its not setting with value or val property.
    <script type="text/javascript">
        function CheckImageTypeAndSize() {
            var aspFileUpload = document.getElementById("FileUpload1");
            var errorLabel = document.getElementById("lbl_uploadMessage");
            var img = document.getElementById("imgUploadThumbnail");           

<pre>
        var fileName = aspFileUpload.value;<br />
        var fileSize; errorLabel.innerHTML = "";

        try {
            fileSize = aspFileUpload.files[0].size; // Size returned in bytes.
        } catch (e) {
            var objFSO = new ActiveXObject("Scripting.FileSystemObject");
            var e = objFSO.getFile(aspFileUpload.value);
            fileSize = e.size;<br />
        }            

        var ext = fileName.substr(fileName.lastIndexOf('.') + 1).toLowerCase();
        if (!(ext == "docx" || ext == "doc" || ext == "pdf")) {
            errorLabel.innerHTML = "Invalid image file, must select a *.doc, *.docx, or *.pdf file.";
            return false;
        }
        if (img.fileSize == -1) {
            errorLabel.innerHTML = "Couldn't load doc file size.  Please try to save again.";
            return false;
        }
        else if (img.fileSize <= 2097152) {
            errorLabel.innerHTML = fileName;
            return true;
        }
        else {                
            var fileSize = (fileSize / 1048576);
            errorLabel.innerHTML = "File is too large, must select file under 20 Mb. File  Size: " + fileSize.toFixed(1).toString() + " Mb";
            return false;
        }
    }

smtp.Host = "localhost";
smtp.Port = 25;

public ActionResult Details(int? id)
{
    if (id == null)
    {
        return View("EmptyPage");
    }
    
    // do something
}

return View("~/Views/Common/EmptyPage.cshtml");