// roman numerals converter in JavaScript.
const romanNumeral= n => {
  let romanString = '';
  let romanValues = [
    ['M', 1000],
    ['CM', 900],
    ['D', 500],
    ['CD', 400],
    ['C', 100],
    ['XC', 90],
    ['L', 50],
    ['XL', 40],
    ['X', 10],
    ['IX', 9],
    ['V', 5],
    ['IV', 4],
    ['I', 1]
  ];

  for (let r of romanValues) {
    while (n >= r[1]) {
      romanString += r[0]
      n -= r[1];
    }
  }

  return romanString;
};

console.log(romanNumeral(350) === 'CCCL');
console.log(romanNumeral(310) === 'CCCX');

console.log(romanNumeral(3) === 'III');
console.log(romanNumeral(5) === 'V');

console.log(romanNumeral(2019) === 'MMXIX');

console.log(romanNumeral(2018) === 'MMXVIII');
console.log(romanNumeral(54) === 'LIV');