<h3>Upload File using Jquery AJAX in Asp.net</h3>

    <table>

        <tr>

        <td>File:</td>

        <td>

            <asp:FileUpload ID="fupload" runat="server"  onchange='prvimg.UpdatePreview(this)' /></td>

        <td><asp:Image ID="imgprv" runat="server" Height="90px" Width="75px"  /></td>

        </tr>

        <tr>

        <td></td>

        <td><asp:Button ID="btnUpload" runat="server" cssClass="button" Text="Upload Selected File" /></td>

        </tr>

    </table>

$("#btnUpload").click(function (evt) {

            var fileUpload = $("#fupload").get(0);

            var files = fileUpload.files;  

            var data = new FormData();

            for (var i = 0; i < files.length; i++) {

                data.append(files[i].name, files[i]);

            }  

            $.ajax({

                url: "FileUploadHandler.ashx",

                type: "POST",

                data: data,

                contentType: false,

                processData: false,

                success: function (result) { alert(result); },

                error: function (err) {

                    alert(err.statusText)

                }

            });  

            evt.preventDefault();

        });  

<%@ WebHandler Language="C#" Class="FileUploadHandler" %>    

using System;

using System.Web;    

public class FileUploadHandler : IHttpHandler

{    

    public void ProcessRequest (HttpContext context)

    {

        if (context.Request.Files.Count > )

        {

            HttpFileCollection files = context.Request.Files;

            for (int i = ; i < files.Count; i++)

            {

                HttpPostedFile file = files[i];

                string fname = context.Server.MapPath("~/uploads/" + file.FileName);

                file.SaveAs(fname);

            }

            context.Response.ContentType = "text/plain";

            context.Response.Write("File Uploaded Successfully!");

        }    

    }    

    public bool IsReusable

    {

        get

        {

            return false;

        }

    }    

}