Gets the number of days in a month (0-11)

getMonthDays.js

// without lookup table
function getMonthDays_A (month, year)
{
    if (month === 1)
        return year % 4 === 0 && (year % 100 !== 0 || year % 400 === 0) ? 29 : 28;

    if (month % 2)
        return month > 6 ? 31 : 30;

    return month > 6 ? 30 : 31;
}

// with lookup table
function getMonthDays_B (month, year)
{
    if (month === 1 && year % 4 === 0 && (year % 100 !== 0 || year % 400 === 0))
        return 29;
        
    return [31,28,31,30,31,30,31,31,30,31,30,31][month];
}

// mini
function getMonthDays_C (month, year)
{
    return (month === 1 && year % 4 === 0 && (year % 100 !== 0 || year % 400 === 0)) ? 29 : [31,28,31,30,31,30,31,31,30,31,30,31][month];
}