roman-number-conversion.js

// this is unfinished as you can guess...

RomanNumerals = {
  dict: {
    I: 1,
    V: 5,
    X: 10,
    L: 50,
    C: 100,
    D: 500,
    M: 1000,
  },
  toRoman: function (number) {
    var self = this;
    return Object.keys(this.dict)
      .reverse()
      .reduce(function (values, current) {
        values.push(Math.floor(number / self.dict[current]));
        number %= self.dict[current];
        return values;
      }, [])
      .map(function (e, i) {
      	return (new Array(e + 1)).join(Object.keys(self.dict).reverse()[i]);
      })
      .filter(Boolean);
  },
  fromRoman: function (roman) {
  	
  }
}

console.log(RomanNumerals.toRoman(1234));
console.log(RomanNumerals.toRoman(4));
console.log(RomanNumerals.toRoman(1990));