functional_fizzbuzz.js

const functionalFizzBuzz = n => {
  
  return Array.from(
    { length: n },
    (_, idx) =>
      [[15, "fizzbuzz"], [5, "buzz"], [3, "fizz"]].find(
        val => (idx + 1) % val[0] === 0
      ) || idx + 1
  ).reduce((acc, el) => (acc += (el[1] || el) + "\n"), "");
  
};

functionalFizzBuzz(15); 

// "1 2 fizz 4 buzz fizz 7 8 fizz buzz 11 fizz 13 14 fizzbuzz"