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unit Singleton.Example;

interface

type
  TMyClass = class
  strict private
    class var FInstance : TMyClass;
  private
    class procedure ReleaseInstance();

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{
  In the Main Form of application
}

procedure TMainUI.DoEnterAsTab(var Msg: TMsg; var Handled: Boolean);
begin
  if Msg.Message = WM_KEYDOWN then
  begin
    if (not (Screen.ActiveControl is TCustomMemo)) and (not (Screen.ActiveControl is TButtonControl)) then
    begin

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program Project1;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils,
  uSingletonGeneric in 'uSingletonGeneric.pas',
  uMyClass in 'uMyClass.pas';

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List of Delphi product/compiler versions and conditional directives:

Product	Product Version	CompilerVersion	Directive
Delphi 10.2 Tokyo	25	32	VER320
Delphi 10.1 Berlin	24	31	VER310
Delphi 10 Seattle	23	30	VER300
Delphi XE8	22	29	VER290
Delphi XE7	21	28	VER280
Delphi XE6	20	27	VER270

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// uses RegularExpressions;

function ValidateEmail(const emailAddress: string): Boolean;
var
  RegEx: TRegEx;
begin
  RegEx := TRegex.Create('^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]*[a-zA-Z0-9]+$');
  Result := RegEx.Match(emailAddress).Success;
end;

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BDS # HKCU/HKLM registry path        Name                                  CompilerVersion RTLVersion Define               Characterset Frameworks DllSuffix ProjectVersion Architectures                                     HKCU                                HKLM                               
----- -----------------------        ----                                  --------------- ---------- ------               ------------ ---------- --------- -------------- -------------                                     ----                                ----                               
    1 \Software\Borland\BDS\1.0      Borland C# Builder 1                  C#              C#         C#                   Unicode      .NET       ????      ????           C# .NET 1                                         hkcu:\Software\Borland\BDS\1.0      hklm:\Software\Borland\BDS\1.0     
    2 \Software\Borland\BDS\2.0      Borland Delphi 8                      none/16.0       none/16.0  VER160/VER160        Ansi/Unicode VCL/.

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{$IFDEF VER80} ShowMessage('Delphi 1');{$ENDIF}
{$IFDEF VER90} ShowMessage('Delphi 2');{$ENDIF}
{$IFDEF VER100} ShowMessage('Delphi 3');{$ENDIF}
{$IFDEF VER120} ShowMessage('Delphi 4');{$ENDIF}
{$IFDEF VER130} ShowMessage('Delphi 5');{$ENDIF}
{$IFDEF VER140} ShowMessage('Delphi 6');{$ENDIF}
{$IFDEF VER150} ShowMessage('Delphi 7');{$ENDIF}
{$IFDEF VER160} ShowMessage('Delphi 8');{$ENDIF}
{$IFDEF VER170} ShowMessage('Delphi 2005');{$ENDIF}
{$IFDEF VER180} ShowMessage('Delphi 2006');{$ENDIF}

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1. Place server.js and sse.html in the same directory
2. npm install hapi nipple
3. node server.js
4. In browser that supports Server Sent Events, navigate to http://localhost:3000/sse.html

• Navigating to this page triggers a connection to /stream.
• /stream connects to /events and proxies the data back to the client.
• /events provides the actual Server Sent Events stream.

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var Hapi = require('hapi');
var stream = require('stream');

// Create a server
var server = Hapi.createServer('localhost', 8000);

// Add a route
server.route({
  method: 'GET',
  path: '/hello',

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Problem

While building a JavaScript single page app that acts as a front-end to multiple backend servers, even if they are on the same host as the web app - but on different ports, you come across CORS issues.

Solution

Use a simple node.js + hapi.js server to:

1. Serve your static single page app
2. Act as proxy to the backend servers