JavaScript函数不返回任何内容

Question

我做了一个函数，可以减少两个数字之间的分数关系。 它可以完美工作，但问题是它不会返回该值。 我已经尝试了各种方法，例如声明一个新变量然后返回它，但是它不起作用。 我还添加了几个console.logs来查看它是否在某个特定位置停止，但是什么也没有，只是没有返回任何东西。

这是我的代码：

function reduceFraction(n, d) {
    var numerator = n;
    var denominator = d;

    if (n % 7 === 0 && d % 7 === 0) {
        numerator /= 7;
        denominator /= 7;
        console.log('Divided by 7');
        reduceFraction(numerator, denominator);
    } else {
        if (n % 5 === 0 && d % 5 === 0) {
            numerator /= 5;
            denominator /= 5;
            console.log('Divided by 5');
            reduceFraction(numerator, denominator);
        } else {
            if (n % 3 === 0 && d % 3 === 0) {
                numerator /= 3;
                denominator /= 3;
                console.log('Divided by 3');
                reduceFraction(numerator, denominator);
            } else {
                if (n % 2 === 0 && d % 2 === 0) {
                    numerator /= 2;
                    denominator /= 2;
                    console.log('Divided by 2');
                    reduceFraction(numerator, denominator);
                } else {
                    console.log('Was not divided by anything');
                    var reduced = numerator + "/" + denominator;
                    return reduced; //console.log(numerator + "/" + denominator); logs 1/18
                }
            }
        }
    }
}
reduceFraction(3, 54);

我不知道是否嵌套一堆if语句必须对此做任何事情，但这是（我能想到的）目前唯一的方法，它将减少一小部分...预先感谢。

Answer 1

在递归函数中，您也需要return ：

更换所有

    reduceFraction(numerator, denominator);

像这样 ：

    return reduceFraction(numerator, denominator);

Answer 2

你必须退还它

 function reduceFraction(n, d) {
    var numerator = n;
    var denominator = d;

    if (n % 7 === 0 && d % 7 === 0) {
        numerator /= 7;
        denominator /= 7;
        console.log('Divided by 7');
        return reduceFraction(numerator, denominator);
    } else {
        if (n % 5 === 0 && d % 5 === 0) {
            numerator /= 5;
            denominator /= 5;
            console.log('Divided by 5');
            return reduceFraction(numerator, denominator);
        } else {
            if (n % 3 === 0 && d % 3 === 0) {
                numerator /= 3;
                denominator /= 3;
                console.log('Divided by 3');
                return reduceFraction(numerator, denominator);
            } else {
                if (n % 2 === 0 && d % 2 === 0) {
                    numerator /= 2;
                    denominator /= 2;
                    console.log('Divided by 2');
                    return reduceFraction(numerator, denominator);
                } else {
                    console.log('Was not divided by anything');
                    var reduced = numerator + "/" + denominator;
                    return reduced; //console.log(numerator + "/" + denominator); logs 1/18
                }
            }
        }
    }
}
return reduceFraction(3, 54);