Fibonnaci with Deno

fibonacci.ts

import { cyan } from "https://deno.land/std@0.103.0/fmt/colors.ts";

export function fib(n: number): number {
  if (0 <= n && n <= 1) {
    return n;
  }

  let a = 0, b = 1;
  for (let i = 0; i < n; i++) {
    [a, b] = [b, a + b];
  }
  return a;
}

if (import.meta.main) {
  console.log(cyan(`${fib(parseInt(Deno.args[0]))}`));
}

fibonacci_test.ts

import {
  assertEquals
} from "https://deno.land/std@0.103.0/testing/asserts.ts";
import { fib } from "./fibonacci.ts";

Deno.test({
  name: "fibonacci numbers",
  fn() {
    assertEquals(fib(0), 0);
    assertEquals(fib(1), 1);
    assertEquals(fib(6), 8);
    assertEquals(fib(10), 55);
  }
});