javascript - 如何打印递归轨迹(阶乘函数)？

Question

为了更好地理解递归，我试图找出如何将递归跟踪记录到控制台。我有“追踪”部分，但我不确定如何“冒泡”解决方案。对完美放置的 console.log 语句有什么建议吗？

这是我到目前为止所得到的:

function factorial (num) {
    if (num === 1) {
        console.log('factorial(' + num + ') = ' + num);
        return 1;
    } else {
        console.log('factorial(' + num + ') = ' + num + ' * ' + 'factorial(' + (num - 1) + ')');
        return num * factorial(num - 1);
    }
}

将以下内容打印到控制台:

factorial(5) = 5 * factorial(4)
factorial(4) = 4 * factorial(3)
factorial(3) = 3 * factorial(2)
factorial(2) = 2 * factorial(1)
factorial(1) = 1
120

但是 1 * 2 * 3 * 4 * 5 部分呢？我知道它发生在某处，我该如何打印它？

我想我希望它看起来像这样:

1
1 * 2
2 * 3
6 * 4
24 * 5
120

感谢您的任何建议!

好的，经过更多搜索后，我在 CodeRanch 找到了这个，不幸的是没有代码(并且用 Java 编写):

Enter fact(6)  
    Enter fact(5)  
        Enter fact(4)  
            Enter fact(3)  
                Enter fact(2)  
                    Enter fact(1)  
                        Enter fact(0)  
                        0!Ret: 1  
                    Ret: 1 * fact(n-1) = 1 * fact(0) = 1 * 1 = 1  
                Ret: 2 * fact(n-1) = 2 * fact(1) = 2 * 1 = 2  
            Ret: 3 * fact(n-1) = 3 * fact(2) = 3 * 2 = 6  
        Ret: 4 * fact(n-1) = 4 * fact(3) = 4 * 6 = 24  
    Ret: 5 * fact(n-1) = 5 * fact(4) = 5 * 24 = 120  
Ret: 6 * fact(n-1) = 6 * fact(5) = 6 * 120 = 720  
fact(6) = 720  

很酷，对吧？经过更多的实验，我仍然无法实现这一目标......

Answer 1

function factorial (num) {
    if (num === 1) {
        console.log(num); //print new line after this
        return 1;
    } else {
        var val = factorial(num - 1);
        console.log(num +'*' + val);  //print new line after this
        return num * val;
    }
}