Page Load is not ending after exporting gridview to Excel

Question

I am trying to export gridview data to the excel. Everything is alright for exporting but after that page load is not ending.

This is the script for "Please wait" in the master page (It shows a gif and says "Please wait while page is loading") :

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
    function ShowProgress() {
        setTimeout(function () {
            var modal = $('<div />');
            modal.addClass("modal");
            $('body').append(modal);
            var loading = $(".loading");
            loading.show();
            var top = Math.max($(window).height() / 2 - loading[0].offsetHeight / 2, 0);
            var left = Math.max($(window).width() / 2 - loading[0].offsetWidth / 2, 0);
            loading.css({ top: top, left: left });
        }, 200);
    }
    $('form').live("submit", function () {
        ShowProgress();
    });
</script>

This is the class where I do export :

public static void Export(string fileName, GridView gv)
{
    HttpContext.Current.Response.Clear();
    HttpContext.Current.Response.AddHeader(
        "content-disposition", string.Format("attachment; filename={0}", fileName));
    HttpContext.Current.Response.ContentType = "application/ms-excel";

    using (StringWriter sw = new StringWriter())
    {
        using (HtmlTextWriter htw = new HtmlTextWriter(sw))
        {
            //  Create a form  to contain the grid
            Table table = new Table();

            //  add  the header row to the table
            if (gv.HeaderRow != null)
            {

                GridViewExportUtil.PrepareControlForExport(gv.HeaderRow);
                table.Rows.Add(gv.HeaderRow);
                //color the header
                table.Rows[0].BackColor = gv.HeaderStyle.BackColor;
                table.Rows[0].ForeColor = gv.HeaderStyle.ForeColor;
            }

            //  add each of the data  rows to the table
            foreach (GridViewRow row in gv.Rows)
            {
                GridViewExportUtil.PrepareControlForExport(row);
                table.Rows.Add(row);
            }

            //  add the footer row to the table
            if (gv.FooterRow != null)
            {
                GridViewExportUtil.PrepareControlForExport(gv.FooterRow);
                table.Rows.Add(gv.FooterRow);
            }


            table.GridLines = gv.GridLines;
            //  render the table into the htmlwriter

            table.RenderControl(htw);
            //  render the htmlwriter into the response
            HttpContext.Current.Response.Write(sw.ToString());
            HttpContext.Current.Response.End();

        }
    }

And this is where I call the method in the master page :

    GridView gridview = (GridView)ContentPlaceHolder1.FindControl("gridview_sales");
    gridview.AllowPaging = false;
    gridview.DataBind();
    GridViewExportUtil.Export("SalesList.xls", gridview);

Answer 1

This is because there can only be on response from the server side. In you case, that response is in a form of an excel file. One way to get around this by setting a timeout in your JavaScript with the code to remove the "Please wait" gif.