String representation of an object - deck cards

Question

I am looking to build a function containing two string variables, and return the combination to each card of a deck.

    playCard({ suit: 'HEARTS', value: 2 }) to return 2♥
    playCard({ suit: 'SPADES', value: 10 }) to return T♠
    playCard({ suit: 'SPADES', value: 11 }) to return J♠

Answer 1

You could do this with 2 simple lookup tables, or associative arrays

const suitsMap = {
  'HEARTS' : '♥',
  'SPADES' : '♠'
  // etc
}

const valuesMap = {
  2 : '2',
  10: 'T',
  11: 'J'
  // etc
}

function playCard({value,suit}){
  return valuesMap[value] + suitsMap[suit];
}

console.log(playCard({ suit: 'HEARTS', value: 2 }))
console.log(playCard({ suit: 'SPADES', value: 10 }))
console.log(playCard({ suit: 'SPADES', value: 11 }))

playCard could have also be written like this:

function playCard(card){
  return valuesMap[card.value] + suitsMap[card.suit];
}

In my example above it simply used object destructuring assignment: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment

Answer 2

I wrote a card game to share with my friends who used to play in person before the epidemic. It uses firebase for real-time state between the players, and it uses these Card and Deck classes to which you're welcome.

The answer to rendering a card as a string (asString()) matches the perfectly acceptable already posted answer, looking up suit and value in a map.

We sometimes have too many players playing large, card-wasting games, so I added a deckId to the Card object and let the Deck object deal through multiple 'shoes'.

class Card {
  constructor(suit, value, deckId) {
    this.suit = suit
    this.value = value
    this.deckId = deckId
  }

  static isEqual(card) {
    return this.value === card.value && this.suit === card.suit && this.deckId === card.deckId
  }

  asString() {
    const valueNames = { 1:'A', 2:'2', 3:'3', 4:'4', 5:'5', 6:'6', 7:'7', 8:'8', 9:'9', 10:'19', 11:'J', 12:'Q', 13:'K' }
    // feel free to replace these with unicode equivalents (my UI uses images)
    const suitNames = { 'h': 'hearts', 'd': 'diamonds', 'c':'clubs', 's':'spades' }
    return `${valuesNames[this.value]} of ${suitNames[this.suit]}`
  }
}

class Deck {
  constructor() {
    this.deckId = this.randomId()
    this.cards = this.freshDeck()
  }

  static randomId () {
    let chars ='abcdefghijklmnopqrstuvwxyz0123456789'.split('')
    this.shuffle(chars)
    return chars.join('').substring(0,8)
  }

  freshDeck () {
    let cards = []
    let suits = ['h', 'c', 'd', 's']
    suits.forEach(suit => {
      for (let value = 1; value <= 13; value++) {
        cards.push(new Card(suit, value, this.deckId))
      }
    })
    return cards
  }

  // fischer-yates shuffle
  static shuffle (array) {
    let currentIndex = array.length, temp, randomIndex;
    while (0 !== currentIndex) {
      randomIndex = Math.floor(Math.random() * currentIndex)
      currentIndex -= 1
      temp = array[currentIndex]
      array[currentIndex] = array[randomIndex]
      array[randomIndex] = temp
    }
  }

  shuffle () {
    Deck.shuffle(this.cards)
    return this
  }

  dealOne () {
    if (this.cards.length === 0) {
      this.deckId = this.randomId()
      this.cards = this.freshDeck()
      this.shuffle()
    }
    let card = this.cards[0]
    this.cards = this.cards.slice(1)
    return card
  }
}