numberToRoman.js

function toRoman(number) {
    'use strict';
    var v = [1000,  900, 500,  400, 100,   90,  50,   40,  10,    9,   5,    4,   1],  // set values
        r = [ 'M', 'CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I'],  // set numerals
        n = Math.round(number), // clean number, round to nearest integer
        limit = 3999, // set max limit to check integers against
        s = '', // create empty string for numerals
        val; // create temp val variable

    // check if number is greater than the limit
    if (n > limit || n < 1) { return ''; }
    // with M as 1000 the greatest number of options is 13
    for (var i = 0; i <= 12; i++) {
        // in order of highest values
        val = v[i];
        // while the number is greater than the value being compared
        while (n >= val) {
            // subtract the value being compared
            n -= val;
            // add the corrosponding roman numeral to the resultant string
            s += r[i];
        }
        // when the value is decremented to 0 return the resulting roman numeral
        if (n === 0) { return s; }
    }
}

Another Solution from Created by Matthew, Daniel, Corey and Ray. https://gist.github.com/rayshan/8670186