Question

我不久前问了一个关于同一批代码的问题，但这次是一个不同的问题。使用我得到的关于这个不同问题的提示，我试图解决这个问题，这是我的JavaScript二十一点游戏中的得分功能。当我在Mozilla Scratchpad上测试时，我的分数功能可以打印出NaN。我已经尝试调整返回，合并两个for循环，甚至重命名我的交易函数中的变量，以确保它不会混淆其他变量，仍然没有。有人问过类似的问题，但这并没有解决我的问题。

function Card (s, n) {
    var suit = s;
    var number = n;
    this.getNumber = function () {
        return number;
    };
    this.getSuit = function () {
        return suit;
    };
    this.getValue = function () {
        if (number > 10) {
            return 10;
        } else if (number === 1) {
            return 11;
        } else {
            return number;
        }
    };
}

var cardNames = {1:"Ace", 2:"2", 3:"3", 4:"4", 5:"5", 6:"6", 7:"7", 8:"8", 9:"9", 10:"10", 11:"Joker", 12:"Queen", 13:"King"};
var suitNames = {1:"Clubs", 2:"Diamonds", 3:"Hearts", 4:"Spades"};

var deal = function () {
    var s = Math.floor(Math.random() * 4 + 1);
    var n = Math.floor(Math.random() * 13 + 1);
    return new Card(s, n);
};

function Hand(){
    var cards = [];
    var card1 = deal();
    var card2 = deal();
    cards = [card1, card2];
    this.getHand = function () {
        return cards;
    };
    this.score = function () {
        var points;
        for (i = 0; i < cards.length; i++) {
            points = points + cards[i].getValue();
        }
        for (i = 0; i < cards.length; i++) {
            if (points > 21 && cards[i].getValue() === 11) {
                points = points - 10;
            }
        } return points;
    };
    this.printHand = function () {
        for (i = 0; i < cards.length; i++) {
            var hand;
            if (i === 0) {
            hand = cardNames[cards[i].getNumber()] + " of " + suitNames[cards[i].getSuit()];
            } else {
            hand = hand + " and a " + cardNames[cards[i].getNumber()] + " of " + suitNames[cards[i].getSuit()];
            }
        } return hand;
    };
    this.hitMe = function () {
        cards.push(deal());
    };
}

var playAsDealer = function () {
    var playDealer = new Hand();
    while (playDealer.score() < 17) {
        playDealer.hitMe();
    }
    this.printHand = function () {
    return playDealer.printHand();
    };
    this.score = function () {
    return playDealer.score();
    };
    return playDealer;
};

var playAsUser = function () {
    var playUser = new Hand();
    var decision = confirm("Your hand is " + playUser.printHand() + ". Click OK to hit or Cancel to stand");
    for (i = 0; decision !== false; i++) {
        playUser.hitMe();
        decision = confirm("Your hand is " + playUser.printHand() + ". Click OK to hit or Cancel to stand");
    }
    this.printHand = function () {
    return playUser.printHand();
    };
    this.score = function () {
    return playUser.score();
    };
    return playUser;
};

var declareWinner = function (userHand, dealerHand) {
    if ((userHand.score < dealerHand.score) || userHand.score > 21) {
        alert("You lose.");
    } else if (userHand.score > dealerHand.score) {
        alert("You win.");
    } else {
        alert("You tied.");
    }
};

var playGame = function () {
    user = playAsUser();
    dealer = playAsDealer();
    declareWinner(user, dealer);
    alert("User got " + user.printHand() + " for a total score of " + user.score());
    alert("Dealer got " + dealer.printHand() + " for a total score of " + dealer.score());
};

playGame();

Answer 1

您只需在points函数中初始化score的值即可。将var points;更改为var points = 0;，您应该没问题。

编辑：由于我确定这是您的下一个问题，因此您还需要实际调用score中的declareWinner功能。您在多个地方使用player.score代替player.score()。

Answer 2

您在申报时绝不会初始化积分。最初将它们初始化为数字，因为当你执行points = points + cards[i].getValue() javascript所做的是它获取LHS和RHS的值然后将它们转换为基元，使得点为字符串''。此外，无论何时您想确保获得一个数字parseInt(arg, base)！

    var points = 0;
    for (i = 0; i < cards.length; i++) {
        points = points + cards[i].getValue();
    }
    for (i = 0; i < cards.length; i++) {
        if (points > 21 && cards[i].getValue() === 11) {
            points = points - 10;
        }
    } return points;

函数返回NaN

2 个答案: