generating report in excel

[WebMethod]
    [System.Web.Script.Services.ScriptMethod(ResponseFormat = System.Web.Script.Services.ResponseFormat.Json)]
    public void ExportToExcel(FormFieldsInfo objFF)
    {
        try
        {
            //FormBuilderDataProvider.ExportToExcel(objFF);

            HttpContext.Current.Response.Clear();
            HttpContext.Current.Response.ClearContent();
            HttpContext.Current.Response.ClearHeaders();

            HttpContext.Current.Response.AddHeader("content-disposition", "attachment;filename=" + objFF.FieldName + "_" + DateTime.Now.ToString("M_dd_yyyy_H_M_s") + ".xls");
            HttpContext.Current.Response.ContentType = "text/xls";
            HttpContext.Current.Response.Write(objFF.FieldHtml);
            HttpContext.Current.Response.Flush();
            HttpContext.Current.Response.End();
            //HttpContext.Current.ApplicationInstance.CompleteRequest();
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

GetFormReport: function(fileName) {

                    var html = '<table><tr><th>Name</th><th>Age</th></tr><tr><td>shyam</td><td>27</td></tr><tr><td>sujan</td><td>30</td></tr><tr><td>dhrub</td><td>25</td></tr></table>';

                    var tableContent = {
                        FormFieldsInfo: { FieldHtml: html, FieldName: fileName }
                    }
                    this.config.method = "ExportToExcel";
                    this.config.url = this.config.baseURL + this.config.method;
                    this.config.data = JSON2.stringify({ "objFF": tableContent.FormFieldsInfo });
                    this.config.ajaxCallMode = 4;
                    this.ajaxCall(this.config);
                }