function Player () {
  this.collection = []; // Cards
  this.decks = [
    // {
    //   name: 'Deck Name',
    //   cards: [], // Card ids
    // }
  ];
}
Player.prototype.checkCurrency = function (type) {
  if (typeof type !== 'undefined') {
    for (var i = 0; i < this.collection.length; i++) {

    }
  }
}