Some variations to change a number value into Roman type.

RomanNumber-challange1.js

var romanValues = new Array(1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1);
var romanStrings = new Array("M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I");

function calculate(hinduArabicNumber) {
   var numb = parseInt(hinduArabicNumber);
   if (isNaN(numb)) {
      alert("Please enter a number");
      return;
   }
   if ( numb > 9999 || numb < 1) {
      alert("Please enter a number between 1 and 9999");
      return;
   }
   var stringFormatOfTheGivenNumberInRoman = '';
   var tempNumb = numb;
   while (tempNumb > 0) {
      var i;
      for (i=0; i < romanValues.length; i++) {
         if ( tempNumb >= romanValues[i] ) {
            stringFormatOfTheGivenNumberInRoman += romanStrings[i];
            tempNumb -= romanValues[i];
            break;
         }
      }
   }
   return stringFormatOfTheGivenNumberInRoman;
};

RomanNumber-challange2.js

var romanValues = new Array(1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1);
var romanStrings = new Array("M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I");
function calculate(hinduArabicNumber) {
   var numb = parseInt(hinduArabicNumber);
   if (!isNaN(numb)) {
      if ( numb <= 9999 || numb > 1) {
         var stringFormatOfTheGivenNumberInRoman = '';
         var tempNumb = numb;
         while (tempNumb > 0) {
            var i;
            for (i=0; i < romanValues.length; i++) {
               if ( tempNumb >= romanValues[i] ) {
                  stringFormatOfTheGivenNumberInRoman += romanStrings[i];
                  tempNumb -= romanValues[i];
                  break;
               }
            }
         }
         return stringFormatOfTheGivenNumberInRoman;
      }
   }
};

RomanNumber-challange3.js

var RomanAlphabet = function () {
   
   this.romanValues = new Array(1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1);
   
   this.romanStrings = new Array("M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I");
   
   this.convertToRomanNumber = function (hinduArabicNumber) {
      var self = this;
      var numb = parseInt(hinduArabicNumber);
      if (!isNaN(numb)) {
         if ( numb <= 9999 || numb > 1) {
            var stringFormatOfTheGivenNumberInRoman = '';
            var tempNumb = numb;
            while (tempNumb > 0) {
               var i;
               for (i=0; i < self.romanValues.length; i++) {
                  if ( tempNumb >= self.romanValues[i] ) {
                     stringFormatOfTheGivenNumberInRoman += romanStrings[i];
                     tempNumb -= romanValues[i];
                     console.log(stringFormatOfTheGivenNumberInRoman);
                     break;
                  }
               }
            }
            return stringFormatOfTheGivenNumberInRoman;
         }
      }
   }
};

RomanNumber-challange4.js

Number.prototype.convertToRomanNumber = function () {
   var romanValues = new Array(1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1);
   var romanStrings = new Array("M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I");
   var numb = parseInt(this);
   if (!isNaN(numb)) {
      if ( numb <= 9999 || numb > 1) {
         var stringFormatOfTheGivenNumberInRoman = '';
         var tempNumb = numb;
         while (tempNumb > 0) {
            var i;
            for (i=0; i < romanValues.length; i++) {
               if ( tempNumb >= romanValues[i] ) {
                  stringFormatOfTheGivenNumberInRoman += romanStrings[i];
                  tempNumb -= romanValues[i];
                  break;
               }
            }
         }
         return stringFormatOfTheGivenNumberInRoman;
      }
   }
};