Export Report as CSV or XLSX or XLS from ReportViewer in ASP.NET

<script type="text/javascript">
$(document).ready(function () {
if ($("#rptScheduledClinicsReport_ctl06_ctl04_ctl00_Menu") != null 
	&& $("#rptScheduledClinicsReport_ctl06_ctl04_ctl00_Menu") != undefined) {
	$('#rptScheduledClinicsReport_ctl06_ctl04_ctl00_Menu').find('div').first().remove();
	$("#rptScheduledClinicsReport_ctl06_ctl04_ctl00_Menu")
	.prepend("<div style='border:1px transparent Solid;'><a onclick='ExportExcelReport();' 
	href='javascript:void(0)' style='color:#3366CC;font-family:Verdana;font-size:8pt;padding:3px 8px 3px 8px;display:block;
	white-space:nowrap;text-decoration:none;'>Excel</a></div>");
	$("#rptScheduledClinicsReport_ctl06_ctl04_ctl00_Menu").prepend("<div style='border:1px transparent Solid;
	'><a onclick='ExportCSVReport();' href='javascript:void(0)' 
	style='color:#3366CC;font-family:Verdana;font-size:8pt;padding:3px 8px 3px 8px;display:block;
	white-space:nowrap;text-decoration:none;'>CSV</a></div>");
}
}
</script>

function ExportCSVReport() {
	__doPostBack("typeCSV", "csv");
}
function ExportExcelReport() {
	__doPostBack("typeExcel", "excel");
}

protected void Page_Load(object sender, EventArgs e)
{
	if (!IsPostBack)
	{
		//To bind RDLC report with data source.
		this.reportBind();
	}
	if (Page.IsPostBack)
	{
		string contact_args = Request["__EVENTARGUMENT"];
		if (!string.IsNullOrEmpty(contact_args) && contact_args.ToLower() == "csv")
			this.ExportCSVReport();	//Exporting CSV from datatable
		if (!string.IsNullOrEmpty(contact_args) && contact_args.ToLower() == "excel")
			this.ExportExcelReport(); //Exporting Excel from ReportViewer
	}
}

/// <summary>
/// This method will be use to download Excel report from ReportViewer
/// </summary>
private void ExportExcelReport()
{
	byte[] bytes = rptEmployeeReport.LocalReport.Render("Excel");
	this.downloadReport(bytes, "xls");
}

/// <summary>
/// This method will use to download CSV format report from DataTable
/// </summary>
protected void ExportCSVReport()
{
	DataTable dt_sc_report = new DataTable();
	DataAccessLib db = new DataAccessLib();
	dt_sc_report = db.getEmployeeReport();

	var export = new ExportToCSV();
	foreach (DataRow row in dt_sc_report.Rows)
	{
		export.AddRow();
		foreach (DataColumn column in dt_sc_report.Columns)
		{
			export[column.ColumnName] = row[column].ToString();
		}
	}

	byte[] csv_data = export.ExportToBytes();
	this.downloadReport(csv_data, "csv");
}

/// <summary>
/// This common function for download report
/// </summary>
/// <param name="data"></param>
/// <param name="format"></param>
private void downloadReport(byte[] data, string format)
{
	Stream stream = new MemoryStream(data);

	byte[] buffer = new Byte[10000];
	int length;
	long data_length;
	try
	{
		data_length = stream.Length;
		Response.ContentType = "application/octet-stream";
		Response.AddHeader("Content-Disposition", "attachment; filename=confirmClinicDetails." + format);

		while (data_length > 0)
		{
			if (Response.IsClientConnected)
			{
				length = stream.Read(buffer, 0, 10000);
				Response.OutputStream.Write(buffer, 0, length);
				Response.Flush();
				buffer = new Byte[10000];
				data_length = data_length - length;
			}
			else
			{
				data_length = -1;
			}
		}
	}
	finally
	{
		if (stream != null) { stream.Close(); }
		Response.Close();
	}
}