Validate number of days in a given month

Question

Performance is of the utmost importance on this one guys... This thing needs to be lightning fast!


How would you validate the number of days in a given mont

Answer 1

function caldays(m,y)
{
    if (m == 01 || m == 03 || m == 05 || m == 07 || m == 08 || m == 10 || m == 12)
    {
        return 31;              
    }
    else if (m == 04 || m == 06 || m == 09 || m == 11)
    {
        return 30;        
    }
    else
    {    
        if ((y % 4 == 0) || (y % 400 == 0 && y % 100 != 0))
        {    
            return 29;          
        }
        else 
        {
            return 28;              
        }
    }    
}

source: http://www.dotnetspider.com/resources/20979-Javascript-code-get-number-days-perticuler-month-year.aspx