Function to create a Fibonacci sequence

fibonacci.ts

/* Fibonacci Sequence */

const fibonacci = (result: number[], len: number) => {
    let n1: number = result[0],
        n2: number = result[1],
        next: number,
        cnt: number = 2;

    while (cnt < len) {
        next = n1 + n2;
        n1 = n2;
        n2 = next;
        result.push(next);
        cnt++;
    }

    return result;
}

console.log(fibonacci([0, 1], 20));