function doKey(const AEvent: THandle): Boolean;
 begin
  result := PerformKeyPress(AEvent.keyCode);
 end;

asm
   document.addEventListener('keydown', (event) => {
     if (@doKey(event)) {
      event.preventDefault();
     }
    });
  end;

I am aware that this might not be the best way, but can easily hook the keyboard event.