Question

I am new to programming and javascript and i have a question ive been struggling with for a bit now. Im trying to build a card game and have a card object which returns a card representation of the format (card #,suit eg. 5,Hearts). I deal a card at the start of the program and validate that the card dealt is unique (ie not been used already). I have the following structure:

var usedCards= [];

function dealCards() {
  for (i = 0; i < 3; i++)
  { 
    var card = createUniqueCard();
    usedCards.push(card.cardRepresentation);
  }
}

function createUniqueCard() {
  do {
    var newCard = new Card();
  }
  while (usedCards.indexOf(newCard.cardRepresentation) != -1);

  return newCard;
}

This still returns me duplicate cards in my usedCards array. Can anyone point out my logic error?

Thanks

Answer 1

If newCard.cardRepresentation is an object then .indexOf() will never find a match because two object references are considered equal only if they refer to the same instance – you keep creating new instances with new Card().

If you can have newCard.cardRepresentation as a string it should work. Or if you write your own function to replace .indexOf(), where your function knows how to compare two .cardRepresentation objects…

I think a better solution is to begin by generating all possible cards, putting them in an array, and then your deal function could randomly select from that array.