CODEWITHSUNDEEP
javascriptarraysfunction
Bijay Timilsina
Bijay Timilsina

Reputation: 757

Updating an array returned by a function

I've been trying to implement some card game using Javascript. In the snippet below, I simply want to pull two cards from the top of the deck and give it to the player (simplified logic below) 

function deck() {
    var faceCards = [['jack', 11],['queen', 12],['king', 13]];
    return faceCards;
}
function removeCard() {
    var singleCard = deck().pop();
    var faceValue = singleCard[0];
    return faceValue;
}
var cardPair = [removeCard(),removeCard()];
console.log(cardPair);

However the faceCards array is still the same even after popping off its cards which means that the next card will be the same as well as seen in cardPair array.

I need to mirror the effects I used inside of the removeCard() function to reflect back in the deck() function.

I suppose I could either create the faceCards array in the global scope or use 'this' in some way (which I don't really want as I'm not much familiar with it). How can I update one function from inside another function? Thank you very much for reading this.

Upvotes: 1

Views: 53

Answers (2)

Alnitak
Alnitak

Reputation: 339836

Your error is here:

var singleCard = deck().pop()

The call to deck() creates a new array of cards every time it's called, and doesn't repeatedly return the same array.

If you don't want to go full OO yet, consider at least passing the deck as a parameter to the removeCard() function, i.e.

function removeCard(deck) {
    var singleCard = deck.pop();
    var faceValue = singleCard[0];
    return faceValue;
}

var deck = newDeck();
var pair = [ removeCard(deck), removeCard(deck) ];

but ultimately you should longer term be going for a full OO solution, where your usage might then become:

var deck = new Deck();
var pair = [ deck.takeCard(), deck.takeCard() ];

implementation of this is out of scope of this particular question.

Upvotes: 2

Stu
Stu

Reputation: 4150

You're creating a new array every time you run deck(). Try saving the deck in an array and running pop on this:

function deck() {
    var faceCards = [['jack', 11],['queen', 12],['king', 13]];
    return faceCards;
}
function removeCard(fromDeck) {
    var singleCard = fromDeck.pop();
    var faceValue = singleCard[0];
    return faceValue;
}
var thisDeck = deck();
var cardPair = [removeCard(thisDeck),removeCard(thisDeck)];
console.log(cardPair);

Upvotes: 2

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