toRome

const myRome = {
  0: '',
  1: 'I',
  2: 'II',
  3: 'III',
  4: 'IV',
  5: 'V',
  6: 'VI',
  7: 'VII',
  8: 'VIII',
  9: "IX",
  10: 'X',
  20: 'XX',
  30: 'XXX',
  40: 'XL',
  50: 'L',
  60: 'LX',
  70: 'LXX',
  80: 'LXXX',
  90: 'XC',
  100: 'C',
  200: 'CC',
  300: 'CCC',
  400: 'CD',
  500: 'D',
  600: 'DC',
  700: 'DCC',
  800: 'DCCC',
  900: 'CM',
  1000: 'M',
}

const toRoman = (number) => {
  if (number > 3999) { return `Please write number less then 4000` }

  const array = '0'.repeat(4 - String(number).length).concat(String(number)).split('').map(Number);

  const [hilyadni, stotici, desetici, edinici] = [...array];

  return myRome[1000].repeat(hilyadni).concat(myRome[100 * stotici]).concat(myRome[10 * desetici]).concat(myRome[edinici])
}





console.log(toRoman(1000));
console.log(toRoman(999));
console.log(toRoman(4));
console.log(toRoman(1));
console.log(toRoman(1991));
console.log(toRoman(2006));
console.log(toRoman(2020));

console.log(toRoman(21));
console.log(toRoman(1));
console.log(toRoman(3));
console.log(toRoman(4));
console.log(toRoman(2007));
console.log(toRoman(1669));