I'm making a hangman game and I would like the ability to use the keyboard when guessing letters. The issue I'm stuck on is I'm not sure how to let the keys be triggered/pressed only one time. I'm using the Keypress library right now and can't seem to find a way to disable keys once they have been pressed. After googling for a while I found that maybe returning 'false' after the key is pressed will disable it but for some reason it only works on keys: 'a', 'g', and 'i'.

Code:
keypress.combo("a",  function(){
  letterClicked('a');
   return false;
    
});

keypress.combo("b", function(){
  letterClicked('b');
  return false;
});

keypress.combo("c", function(){
  letterClicked('c');
  return false;
});

keypress.combo("d", function(){
  letterClicked('d');
  return false;
   
});

keypress.combo("e", function(){
  letterClicked('e');
  return false;
}); ////............ and it goes like this for the rest of the alphabet.