// ******************************************************************
// This function accepts a string variable and verifies if it is a
// proper date or not. It validates format matching either
// mm-dd-yyyy or mm/dd/yyyy. Then it checks to make sure the month
// has the proper number of days, based on which month it is.

// The function returns true if a valid date, false if not.
// ******************************************************************
function isDate(dateStr)
{
    var datePat = /^(\d{1,2})(\/|-)(\d{1,2})(\/|-)(\d{4})$/;
    var matchArray = dateStr.match(datePat); // is the format ok?

    if (matchArray == null)
    {
        alert("Please enter date as either mm/dd/yyyy or mm-dd-yyyy.");
        return false;
    }

    month = matchArray[1]; // p@rse date into variables
    day = matchArray[3];
    year = matchArray[5];

    if (month < 1 || month > 12)
    { // check month range
        alert("Month must be between 1 and 12.");
        return false;
    }

    if (day < 1 || day > 31)
    {
        alert("Day must be between 1 and 31.");
        return false;
    }

    if ((month == 4 || month == 6 || month == 9 || month == 11) && day == 31)
    {
        alert("Month " + month + " doesn`t have 31 days!")
        return false;
    }

    if (month == 2)
    { // check for february 29th
        var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
        if (day > 29 || (day == 29 && !isleap))
        {
            alert("February " + year + " doesn`t have " + day + " days!");
            return false;
        }
    }
    
    return true; // date is valid
}

if (typeof (Sys) != 'undefined') Sys.Application.notifyScriptLoaded();