https://www.reddit.com/r/dailyprogrammer/comments/3q9vpn/20151026_challenge_238_easy_consonants_and_vowels/

random-word-generator.js

var consonants = 'bcdfghjklmnpqrstvwxyz'.split('');
var vowels = 'aeiou'.split('');
var CONSONANT = 'c';
var VOWEL = 'v';
var input = ['cvcvcc', 'CcvV', 'cvcvcvcvcvcvcvcvcvcv'];

function generateWord(pattern) {
	return pattern.split('').map(function(ch, idx, arr) {
		var isUpperCase = ch === ch.toUpperCase();
		var char = ch.toLowerCase();

        if (char === CONSONANT) {
            var randomChar = consonants[Math.floor(Math.random() * consonants.length)];
        	return isUpperCase ? randomChar.toUpperCase() : randomChar; 
        } else if (char === VOWEL) {
			var randomChar = vowels[Math.floor(Math.random() * vowels.length)];
            return isUpperCase ? randomChar.toUpperCase() : randomChar;
        }

    }).join('');
}


console.log(input.map(generateWord));