function daysInFebruary(year) {
    // February has 29 days in any year evenly divisible by four,
    // EXCEPT for centurial years which are not also divisible by 400.
    return (((year % 4 === 0) && ((!(year % 100 === 0)) || (year % 400 === 0))) ? 29 : 28);
}

function DaysArray(n) {
    for (var i = 1; i <= n; i++) {
        this[i] = 31;
        if (i === 4 || i === 6 || i === 9 || i === 11) { this[i] = 30 }
        if (i === 2) { this[i] = 29 }
    }
    return this;
}