Javascript - Loop through object with array property

Question

I am trying out a simple BlackJack game with JS. Here are some of my codes:

 function card(suit, face) {
    this.suit = suit;
    this.face = face;

    switch (face) {
        case "A":
            this.faceValue = 11;
            break;
        case "J":
        case "Q":
        case "K":
            this.faceValue = 10;
            break;
        default:
            this.faceValue = parseInt(face);
            break;
    }
};

const player = {
    cards: [],
    handValue: 0
}

const dealOneCardToPlayer = () => {     
    tempCard = deck.cards.splice(0, 1);
    player.cards.push(tempCard);
    player.handValue = countHandValue(player.cards);
}

I am stuck with countHandValue method which I couldn't get the faceValue of Cards for player object. I try with several types of for loop but with no success still. Once I can get the faceValue, then I can sum it up and assign to handValue property.

const countHandValue = (cardsOnHand) => {    
    for (const key of cardsOnHand) {
        console.log(key.faceValue);
    }

    for (const key in cardsOnHand) {
        console.log(key.faceValue);
    }
}

[Code Edited]I searched and found this code which i can retrieve my faceValue property but I believe there are much extra code:

    const countHandValue = (cardsOnHand) => {
    let sum = 0;
    for (var key in cardsOnHand) {
        var arr = cardsOnHand[key];
        for (var i = 0; i < arr.length; i++) {
            var obj = arr[i];
            for (var prop in obj) {
                if (prop === "faceValue") {
                    console.log(prop + " = " + obj[prop]);
                    sum = sum + obj[prop];                        
                }                    
            }
        }
    }        
    return sum;
}

Answer 1

您可以只使用reduce ：

const coundHandValue = cards => cards.reduce((acc, { faceValue }) => acc + faceValue, 0);

Answer 2

Do consider that A can score as 1 or 11. This program shows you how to handle that -

 const add = (x = 0, y = 0) => x + y const sum = (a = []) => a .reduce (add, 0) const scoreCard = (face = "") => face === "A" ? [ 11, 1 ] : (face === "K") || (face === "Q") || (face === "J") ? [ 10 ] : [ Number (face) ] const allScores = ([ face = "", ...more ]) => face === "" ? [ scoreCard (face) ] : allScores (more) .flatMap ( hand => scoreCard (face) .map (v => [ v, ...hand ]) ) const scoreHand = (...hand) => { const [ best = "Bust" ] = allScores (hand) .map (sum) .filter (score => score <= 21) if (best === 21) return "Blackjack!" else return String (best) } console .log ( scoreHand ("A", "K") // Blackjack! , scoreHand ("A", "A", "K") // 12 , scoreHand ("A", "A", "K", "7") // 19 , scoreHand ("J", "4", "K") // Bust , scoreHand ("A", "A", "A", "A", "K", "7") // Blackjack! )