Javascript: how to validate dates in format MM-DD-YYYY?

Solution 1:

function isValidDate(date)
{
    var matches = /^(\d{1,2})[-\/](\d{1,2})[-\/](\d{4})$/.exec(date);
    if (matches == null) return false;
    var d = matches[2];
    var m = matches[1] - 1;
    var y = matches[3];
    var composedDate = new Date(y, m, d);
    return composedDate.getDate() == d &&
            composedDate.getMonth() == m &&
            composedDate.getFullYear() == y;
}
console.log(isValidDate('10-12-1961'));
console.log(isValidDate('12/11/1961'));
console.log(isValidDate('02-11-1961'));
console.log(isValidDate('12/01/1961'));
console.log(isValidDate('13-11-1961'));
console.log(isValidDate('11-31-1961'));
console.log(isValidDate('11-31-1061'));

It works. (Tested with Firebug, hence the console.log().)

Solution 2:

function isValidDate(date) {
        var valid = true;

        date = date.replace('/-/g', '');

        var month = parseInt(date.substring(0, 2),10);
        var day   = parseInt(date.substring(2, 4),10);
        var year  = parseInt(date.substring(4, 8),10);

        if(isNaN(month) || isNaN(day) || isNaN(year)) return false;

        if((month < 1) || (month > 12)) valid = false;
        else if((day < 1) || (day > 31)) valid = false;
        else if(((month == 4) || (month == 6) || (month == 9) || (month == 11)) && (day > 30)) valid = false;
        else if((month == 2) && (((year % 400) == 0) || ((year % 4) == 0)) && ((year % 100) != 0) && (day > 29)) valid = false;
        else if((month == 2) && ((year % 100) == 0) && (day > 29)) valid = false;
        else if((month == 2) && (day > 28)) valid = false;

    return valid;
}

This checks for valid days in each month and for valid leap year days.

Solution 3:

How about validating dates in "ANY" date format? I've been using the DateJS library and adding it to existing forms to ensure that I get valid dates & times formatted the way that I want. The user can even enter things like "now" and "tomorrow" and it will be converted into a valid date.

Here's the dateJS library: http://www.datejs.com/

and here's a jQuery tip that I wrote: http://www.ssmedia.com/utilities/jquery/index.cfm/datejs.htm