Want simple JS demo

[Kristy]

Thanks Alexandre, it's work now.
I add comment for it.
(Hope this forum support monospaced font)
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implementation

{$R *.dfm}
var user_TZOS : string; // for global used

procedure TIWForm1.IWAppFormCreate(Sender: TObject);
begin
  HIDDEN_TZOS_EDIT.Text := 'No Changed';
  user_TZOS            := 'No Changed';

// On Create, run the javascript and DISPLAY UnControllable ajax value to EDIT field (Its not real value in EDIT.TEXT)
// (The FIELD NAME must all Upper case characters)
  Self.JavaScript.Add('document.addEventListener("DOMContentLoaded", function() {' + sLineBreak +
  'var d = new Date();' + sLineBreak +
  'var tn = d.getTimezoneOffset();' + sLineBreak +
  'document.getElementById("HIDDEN_TZOS_EDIT").value = tn;' + sLineBreak +
  '});');

// Make an event call to FIRE 'AJAX_Func' function, by Pre-Defined Tstrings(use of Javascript) "timeZoneOffset" variable
  IWButton1.ScriptEvents.HookEvent('onclick', 'ajaxCall("AJAX_Func", "timeZoneOffset=" + IW.$("HIDDEN_TZOS_EDIT").value);');

// Registed ajax function and define Converting Procedure
  WebApplication.RegisterCallBack('AJAX_Func', procedure (aParams: TStrings)
                                                  begin
                                                    // Let the EDIT.TEXT display value to be real controllable
                                                    HIDDEN_TZOS_EDIT.Text := aParams.Values['timeZoneOffset'];
                                                    user_TZOS := aParams.Values['timeZoneOffset'];
                                                  end);
end;

procedure TIWForm1.IWButton2AsyncClick(Sender: TObject; EventParams: TStringList);
begin
  Webapplication.ShowMessage('HIDDEN_TZOS_EDIT : ' + HIDDEN_TZOS_EDIT.Text);
  Webapplication.ShowMessage('Global variable user_TZOS : ' + user_TZOS);
end;


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More ! For remark...

HTTP.sys isn't compatible with the ASP.NET Core Module and can't be used with IIS or IIS Express.
https://docs.microsoft.com/en-us/aspnet/...etcore-2.2

Hope no need to touch that
https://support.microsoft.com/en-us/help...or-windows

(My IIS uninstallation may be not clear enough, still finding out how)