getMonthLength()

I use this function everytime i am working with some type of time handling or validation.

function getMonthLength(month,year) {
    var monthlength = new Array(31,28,31,30,31,30,31,31,30,31,30,31);
    if (month==1 && (year/4==Math.floor(year/4) || 
        year/400==Math.floor(year/400)))        
    {
        return 29;
    }
    else return monthlength[month];
}