TypeScript recursive factorial function

2014-12-25 (Thursday) | 100 words (~1 minutes reading)

This is a factorial(factor) function in TypeScript that uses recursion.

function factorial(factor: number): number {
    if (factor <= 1) {
        return 1;
    }
    return factor * factorial(factor - 1);
}

Jest tests:

describe(factorial.name,  () => {
    test("recursive factorial", () => {
        expect(factorial(0)).toBe(1);
        expect(factorial(1)).toBe(1);
        expect(factorial(2)).toBe(2);
        expect(factorial(3)).toBe(6);
        expect(factorial(4)).toBe(24);
        expect(factorial(5)).toBe(120);
        expect(factorial(6)).toBe(720);
        expect(factorial(7)).toBe(5040);
    })
});

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