Roman <=> Integer (JavaScript)

gistfile1.js

var RomanEmpire = {

  emperor: "Claudio Cicali",

  numbers: {
    letters:  [ "M",    "D",   "C",   "L",  "X",  "V", "I" ],
    integers: [ "1000", "500", "100", "50", "10", "5", "1" ]
  },

  romanFor: function(integer) {
    return this.numbers.letters[this.numbers.integers.indexOf("" + integer)];
  },
  
  integerFor: function(roman) {
    return parseInt(this.numbers.integers[this.numbers.letters.indexOf(roman)], 10) || 0;
  }
  
}

RomanEmpire.Number = function(repr) {

  var value = {
    integer: 0,
    roman: ''
  };

  var outputType;

  if (isNaN(repr)) {
    outputType = 'integer';
    value.integer = parseRoman(repr, 0);
    value.roman   = repr;
    if (parseInteger("" + value.integer) != value.roman) {
      throw ("Duo numeri non equatur! " + (value.roman) + " != " + (value.integer));
    }
  } else {
    outputType = 'roman';
    value.roman   = parseInteger("" + repr);
    value.integer = repr;
    if (parseRoman(value.roman, 0) != value.integer) {
      throw ("Duo numeri non equatur! " + (value.integer) + " != " + (value.roman));
    }
  }

  function parseRoman(roman, acc) {

    if (!roman[0]) {
      return acc;
    }

    var d0 = RomanEmpire.integerFor(roman[0])
      , d1 = RomanEmpire.integerFor(roman[1]);

    switch ( true ) {

      case d1 <= d0:
        return parseRoman( roman.substr( 1 ), acc + d0 );

      case d1 > d0:
        return parseRoman( roman.substr( 2 ), acc + ( d1 - d0 ) );

    }
  }

  function parseInteger(integer) {

    var mult;
    var number = "";
    var tmp;

    while (integer.length > 0) {

      if (integer[0] > 0) {

        mult = Math.pow(10, integer.length - 1);
        tmp = parseInt((integer[0] * mult));

        /* This is for "special, edge cases". 
         * Example for "4": mult is 1 and and K esists so that K - 1 = 4. In that case K is 5 so I use R(1) + R(5) which is IV
         * Example for "400": mult is 100 and and K esists so that K - 100 = 400. In that case K is 500 so I use R(100) + R(500) which is CD
         */
        if (!RomanEmpire.numbers.integers.some(function(value) {
          if ( (value - tmp ) == mult ) {
            number += (RomanEmpire.romanFor(mult) + RomanEmpire.romanFor(value));
            return true;
          }
          return false;
        })) {
          RomanEmpire.numbers.integers.forEach(function(value) {
            while ((tmp - value) >= 0) {
              tmp -= value;
              number += RomanEmpire.romanFor(value);
            }
          });
        } 
      }

      integer = integer.substr(1);
    }

    return number;

  }

  return {

    converted: function() {
      return value[outputType];
    }

  };

}

var lines = [], n;

process.stdin.resume();

process.stdin.on('data', function(chunk){
  lines.push(chunk.toString());
});

process.stdin.on('end', function(){
  lines.join("").split("\n").forEach(function(number) {
    n = new RomanEmpire.Number(number);
    console.log(n.converted());
  });
});