JavaScript Recursive.js

function power(num, pow) {
    return pow !== 0 ? num * power(num, pow - 1) : 1;
}

function factorial(num) {
    return num !== 0 ? num * factorial(num - 1) : 1;
}

// test
factorial(5)

5 * factorial(4)
    4 * factorial (3)
        3 * factorial(2)
            2 * factorial(1)
                1 * factorial(0)
                    1
                    1
                1 * 1
            2 * 1 * 1
        3 * 2 * 1 * 1
    4 * 3 * 2 * 1 * 1
5 * 4 * 3 * 2 * 1 * 1