函数isValid始终在NodeJ上返回undefined

Question

所以我尝试调用函数isValid，它总是返回无效。我在返回之前放了一个console.log，它可以工作。

有效总是未定义的。我该怎么做才能解决这个问题？我用javascript非常棒。一切都很完美，只是函数dosnt返回数字i。

var valid = isValid(houseNew, gameID, 1);

function isValid(card, gameID, ph) {
var cardnumbers = 0;
con.query("SELECT * FROM games WHERE id = " + gameID, function (err, result) {
    if (err) throw err;
    var cards = [];
    cards.push(result[0].player1);
    cards.push(result[0].player2);
    cards.push(result[0].player3);
    cards.push(result[0].player4);
    cards.push(result[0].player5);
    cards.push(result[0].house1);
    cards.push(result[0].house2);
    cards.push(result[0].house3);
    cards.push(result[0].house4);
    cards.push(result[0].house5);
    for(var i = 0; i<10; i++)
    {
        if(cards[i] == card) {
            cardnumbers++;
        }
    }
    if(cardnumbers >= 4) {
        return 0;
    }
    else {
        if(ph == 0) {
            var lastCard;
            var i=0;
            lastCard = cards[i];
            i++;
            while(i<=4 && lastCard != 0) {
                lastCard = cards[i];
                i++;
            }
            if(lastCard == 0) {
                return i;
            }
            else {
                return 10;
            }
        } else if (ph == 1) {
            var lastCard;
            var i=0;
            lastCard = cards[i + 5];
            i++;
            while(i<=4 && lastCard != 0) {
                lastCard = cards[i + 5];
                i++;
            }
            if(lastCard == 0) {
                return i;
            }
            else {
                return 10;
            }
        }
    }
});

}