roman-number-encode-decode.js

const RomanNumerals = {
  toRoman: v => {
    let s = '';
    RomanNumerals.numerals.forEach(n => {
      while (v >= n[1]) {
        s += n[0];
        v -= n[1]; 
      }
    });
    return s;
  },

  fromRoman: s => {
    let v = 0;
    RomanNumerals.numerals.forEach(function(n) {
      while (s.substr(0, n[0].length) == n[0]) {
        s = s.substr(n[0].length);
        v += n[1];
      }
    });
    return v;
  },

  numerals: [
    ['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]
  ]
};

// const RomanNumerals = {
//   toRoman: number => {
//     const digits = number.toString().split``,
//         	key = ['','C','CC','CCC','CD','D','DC','DCC','DCCC','CM',
//   		           '','X','XX','XXX','XL','L','LX','LXX','LXXX','XC',
//   		           '','I','II','III','IV','V','VI','VII','VIII','IX'];
//     let result = '',
//   		  i = 3;
//   	while (i--)
//   		result = (key[+digits.pop() + (i * 10)] || '') + result;
//   	return Array(+digits.join`` + 1).join`M` + result;
//   },
  
//   fromRoman: string => {
//     string = string.toUpperCase();
// 		let validator = /^M*(?:D?C{0,3}|C[MD])(?:L?X{0,3}|X[CL])(?:V?I{0,3}|I[XV])$/,
// 		    token = /[MDLV]|C[MD]?|X[CL]?|I[XV]?/g,
// 		    key = {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},
// 		    num = 0, 
//         m;
//   	if (!(string && validator.test(string)))
//       return false;
//   	while (m = token.exec(string)) 
//       num += key[m[0]];
//   	return num;
//   }
// }