http://www.freecodecamp.com/nirajkrz 's solution for Bonfire: Roman Numeral Converter

bonfire-roman-numeral-converter.js

// Bonfire: Roman Numeral Converter
// Author: @nirajkrz
// Challenge: http://www.freecodecamp.com/challenges/bonfire-roman-numeral-converter
// Learn to Code at Free Code Camp (www.freecodecamp.com)

function convert(num) {
 if (!+num)
        return false;
    var digits = String(+num).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"],
        roman = "",
        i = 3;
    while (i--)
        roman = (key[+digits.pop() + (i * 10)] || "") + roman;
    return Array(+digits.join("") + 1).join("M") + roman;
}

convert(36);