How can I check if user passes a valid date in javascript?

Question

I have a javascript function that checks for a date range. Is there any way to check if a user has input a valid date in a textbox, regardless of format?

function checkEnteredDate() {
            var inputDate = document.getElementById('txtDate');
            //if statement to check for valid date
            var formatDate = new Date(inputDate.value);
            if (formatDate > TodayDate) {
                alert("You cannot select a date later than today.");
                inputDate.value = TodayDate.format("MM/dd/yyyy");
            }
}

Answer 1

take a look at this library date.js http://code.google.com/p/jqueryjs/source/browse/trunk/plugins/methods/date.js

it has a useful function called fromString which will try and convert a string (based on Date.format) to a valid date object.

the function returns false if it doesn't create a valid date object - you can then try a different format before giving up if all return false.

here are some example formats you could test for:

Date.format = 'dd mmm yyyy';
alert(Date.fromString("26 Jun 2009"));

Date.format = 'mmm dd yyyy';
alert(Date.fromString("Jun 26 2009"));

Date.format = 'dd/mm/yy';
alert(Date.fromString("26/06/09"));

Date.format = 'mm/dd/yy';
alert(Date.fromString("06/26/09"));

Date.format = 'yyyy-mm-dd';
alert(Date.fromString("2009-06-26"));

Josh