In Javascript, you can define an anonymous function that can be executed immediately. It is called an Immediate Invocation Function Expression, aka IIFE.

First, you declare the function, like so:

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function () {
    console.log('Immediately invoked function execution');
}

Then, you wrap it up in ():

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(function () {
    console.log('Immediately invoked function execution');
})

Finally, you add another () to execute it:

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(function () {
    console.log('Immediately invoked function execution');
})()

In Delphi, similarly, you can define an anonymous method:

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procedure begin
  WriteLn('Hello world');
end

Then, you wrap it up with ():

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(procedure begin
  WriteLn('Hello world');
end)

And finally, execute it!

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(procedure begin
  WriteLn('Hello world');
end)();

Here's another example:

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WriteLn((function (const X: string): Boolean
   begin
     WriteLn(X);
     Result := True;
   end)('Hello'));

The output for this shows the following x:

Hello
TRUE