$.ajax({
                 xhr: function () {
                     var xhr = new window.XMLHttpRequest();
                   
                     //Download progress
                     xhr.addEventListener("progress", function (evt) {
                         console.log("Event :"+evt.lengthComputable);
                         if (evt.lengthComputable) {
                             var percentComplete = evt.loaded / evt.total;
                             //Do something with download progress
                             console.log(percentComplete);
                         }
                     }, false);
                     return xhr;
                 },
                 type: 'POST',
                 url: "Downloader.ashx",
             
                 success: function (data) {
                     //Do something success-ish
                 }
             });

  public void ProcessRequest(HttpContext context)
        {
            DownLoadFilesFromFTp("MyFile.pdf", "Foldername");
            
        }
        public bool DownLoadFilesFromFTp(string fileName,string ftpFolder)
        {
            //Create FTP Request.
            try
            {
                string Ftp_Host = System.Configuration.ConfigurationManager.AppSettings["Ftp_Host"];
                string Ftp_UserName = System.Configuration.ConfigurationManager.AppSettings["Ftp_UserName"];
                string Password = System.Configuration.ConfigurationManager.AppSettings["Password"];
                string downloadpath= System.Configuration.ConfigurationManager.AppSettings["downloadpath"];
                //Fetch the Response and read it into a MemoryStream object.
                string ftpurl = Ftp_Host + ftpFolder + "/" + fileName;
                FtpWebRequest reqFTP;
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpurl));
                reqFTP.Credentials = new NetworkCredential(Ftp_UserName, Password);
                reqFTP.KeepAlive = false;
                reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
                reqFTP.UseBinary = true;
                reqFTP.Proxy = null;
                reqFTP.UsePassive = false;

                FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
                Stream responseStream = response.GetResponseStream();
                FileStream writeStream = null;
                //if (fileName.Substring(fileName.Length - 3, 3) == "pdf" || fileName.Substring(fileName.Length - 3, 3) == "PDF")
                //{
                writeStream = new FileStream(downloadpath + fileName, FileMode.Create);


                //}
                int Length = 2048;  // 2048;

                Byte[] buffer = new Byte[Length];
                int bytesRead = responseStream.Read(buffer, 0, Length);
                while (bytesRead > 0)
                {
                    writeStream.Write(buffer, 0, bytesRead);
                    bytesRead = responseStream.Read(buffer, 0, Length);
                }


                responseStream.Close();
                writeStream.Close();
                response.Close();
                return true;
            }
            catch (WebException wEx)
            {
                return false;

            }
            catch (Exception ex)
            {
                return false;

            }
        }