Plain Code

function generatePassword(limit, inclNumbers) {
    var vowels = 'aeiou'.split('');
    var constonants = 'bcdfghjklmnpqrstvwxyz'.split('');
    var word = '', i, num;

    if (!limit) limit = 8;

    for (i = 0; i < (inclNumbers ? limit - 3 : limit); i++) {
        if (i % 2 == 0) { // even = vowels
            word += vowels[Math.floor(Math.random() * 4)]; 
        } else {
            word += constonants[Math.floor(Math.random() * 20)];
        } 
    }

    if (inclNumbers) {
        num = Math.floor(Math.random() * 99) + '';
        if (num.length == 1) num = '00' + num;
        else if (num.length == 2) num = '0' + num;
        word += num;
    }

    return word.substr(0, limit);
}