Unable to access constructor's value from a prototype in javascript?

Question

JSFiddle

Question: Why is this.decks.push(data); coming up undefined? How can I get deckCtrl.decks to properly log out?

Error: Uncaught TypeError: Cannot read property 'push' of undefined

var DECK_DATA = {};
DECK_DATA.cards = [
    {
        faces: [
            {
                name: 'a',
                src: '',
                link: ''
            },
            {
                name: 'b',
                src: '',
                link: ''
            },
            {
                name: 'b',
                src: '',
                link: ''
            }
        ]
    },
    {
        faces: [
            {
                name: 'a',
                src: '',
                link: ''
            },
            {
                name: 'b',
                src: '',
                link: ''
            },
            {
                name: 'b',
                src: '',
                link: ''
            }
        ]
    }
];
//Classes
var Deck = (function () {
    function Deck(card) {
        this.cards = card;
    }
    return Deck;
})();
var DeckController = (function () {
    function DeckController() {
        this.decks = [];
    }
    DeckController.prototype.addDeck = function (data) {
        console.log(data, this.decks); //this.decks comes up undefined.
        this.decks.push(data);
    };
    return DeckController;
})();
//main
var deckBuilder = Deck;
var deckCtrl = DeckController;
DECK_DATA.cards.forEach(function (item) {
    deckCtrl.prototype.addDeck(new deckBuilder(item));
});
console.log(deckCtrl.decks);

Gavriel · Accepted Answer · 2016-02-07 03:24:01Z

2

You need to use new to create a new instance:

var deckBuilder = new Deck();
var deckCtrl = new DeckController();

And you want to use the addDeck of the instance, not of the prototype:

DECK_DATA.cards.forEach(function (item) {
    deckCtrl.addDeck(new deckBuilder(item));
});

answered Feb 7, 2016 at 3:24

Gavriel

19.3k13 gold badges73 silver badges116 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Unable to access constructor's value from a prototype in javascript?

JSFiddle

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related