plural.js

var plural = function(number, one, two, five) {
    var n = Math.abs(number);

    n %= 100;
    if (n >= 5 && n <= 20) return number + ' ' + five;

    n %= 10;
    if (n == 1) return number + ' ' + one;

    if (n >= 2 && n <= 4) return number + ' ' + two;

    return number + ' ' + five;
}