get clicked element id with javascript not jquery - asp.net-mvc

Question

I have 2 buttons that are in a popup.when each button clicked, popup perform callback .
my problem is when popup make callback i want to know which button clicked and Causes callback
i wrote this code but it don't work , Because in BeginCallback property S.name is the name of popup also e.buttonID is null Because Html.DevExpress().Button dont render input with button type ,it render td and div tag
please help me.
#Html.DevExpress().PopupControl(
settings =>
{
settings.Name = "GetDatepopUp";
settings.PopupElementID = "GetDate";
settings.PopupAction = PopupAction.LeftMouseClick;
settings.CloseAction = CloseAction.CloseButton;
settings.Modal = true;
settings.ShowOnPageLoad = false;
settings.LoadContentViaCallback = LoadContentViaCallback.OnPageLoad;
settings.SetContent(() =>
{
#Html.RenderPartial("CalenderContainerPartialView", "Message");
});
settings.CallbackRouteValues =
new { Controller = "Message", Action = "Calender" };
settings.ClientSideEvents.BeginCallback =
"function(s,e) { e.customArgs['btnName'] = s.name; }";
settings.SetFooterTemplateContent(c =>
{
ViewContext.Writer.Write("<Table style='width:100%'><tr><td>");
Html.DevExpress().Button(buttonsettings =>
{
buttonsettings.Name = "btnNext";
buttonsettings.Text = "<<";
buttonsettings.ClientSideEvents.Click =
"function(s, e) { GetDatepopUp.PerformCallback(); }";
}).Render();
ViewContext.Writer.Write("</td><td>");
Html.DevExpress().Button(buttonsettings =>
{
buttonsettings.Name = "btnPrevious";
buttonsettings.Text = ">>";
buttonsettings.ClientSideEvents.Click =
"function(s, e) { GetDatepopUp.PerformCallback(); }";
}).Render();
ViewContext.Writer.Write("</td></tr></table>");
});
}).GetHtml()

Answer 1

try changing:
GetDatepopUp.PerformCallback();
to this:
GetDatepopUp.PerformCallback('btnPrevious');