สอบถามเกี่ยวกับ JS Alert: Page.ClientScript.RegisterStartupScript() ใน VB.NET ค่ะ

Protected Sub btnCancel_Click(ByVal sender As Object, ByVal e As System.EventArgs) 'Handles btnCancel.ServerClick
        Dim Cn As New OleDb.OleDbConnection(StrConn)
        Dim CnSeat As New OleDb.OleDbConnection(StrConn)

        'MsgBox("Confirm to delete your booking.", MsgBoxStyle.Exclamation + MsgBoxStyle.MsgBoxSetForeground + MsgBoxStyle.OkOnly, "Message from Air Bus Booking")
        'Alert
        'Response.Write("<script language='javascript'>window.alert('Confirm to delete your booking.');</script>")
        Page.ClientScript.RegisterStartupScript(btnCancel.GetType, "Alert", "alert('Confirm to delete your booking.');", True)

        DeleteData(Cn) 'Delete WEBAPPD.ABK010P
        DeleteSeat(CnSeat) 'Delete WEBAPPD.ABK020P

        Session("Ext") = Nothing
        Session("Bkk") = Nothing
        Session("DepartBkk") = Nothing
        Session("Lbe") = Nothing
        Session("DepartLbe") = Nothing
        Session("Lbm") = Nothing
        Session("DepartLbm") = Nothing

        'MsgBox("Delete your booking complete.", MsgBoxStyle.MsgBoxSetForeground + MsgBoxStyle.OkOnly, "Message from Air Bus Booking")
        'Alert
        'Response.Write("<script language='javascript'>window.alert('Delete your booking complete.');</script>")
        'Response.Write("<script language='javascript'>window.location.href('AirBusMenu.aspx');</script>")
        Page.ClientScript.RegisterStartupScript(****.GetType, "", "alert('Delete your booking complete.');location.href='AirBusMenu.aspx';", True)

        Exit Sub

    End Sub