javascript regex iso datetime

Question

does anyone have a good regex pattern for matching iso datetimes?

ie: 2010-06-15T00:00:00

Answer 1

For the strict, full datetime, including milliseconds, per the W3C's take on the spec.:

//-- Complete precision:
/\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+([+-][0-2]\d:[0-5]\d|Z)/

//-- No milliseconds:
/\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z)/

//-- No Seconds:
/\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z)/

//-- Putting it all together:
/(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+([+-][0-2]\d:[0-5]\d|Z))|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z))|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z))/

.
Additional variations allowed by the actual ISO 8601:2004(E) doc:

/********************************************
**    No time-zone varients:
*/
//-- Complete precision:
/\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+/

//-- No milliseconds:
/\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d/

//-- No Seconds:
/\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d/

//-- Putting it all together:
/(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+)|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d)|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d)/

WARNING: This all gets messy fast, and it still allows certain nonsense such as a 14th month. Additionally, ISO 8601:2004(E) allows a several other variants.

.
"2010-06-15T00:00:00" isn't legal, because it doesn't have the time-zone designation.

Answer 2

Not sure if it's relevant to the underlying problem you are trying to solve, but you can pass an ISO date string as a constructor arg to Date() and get an object out of it. The constructor is actually very flexible in terms of coercing a string into a Date.

Answer 3

The ISO 8601 specification allows a wide variety of date formats. There's a mediocre explanation as to how to do it here. There is a fairly minor discrepancy between how Javascript's date input formatting and the ISO formatting for simple dates which do not specify timezones, and it can be easily mitigated using a string substitution. Fully supporting the ISO-8601 specification is non-trivial.

Here is a reference example which I do not guarantee to be complete, although it parses the non-duration dates from the aforementioned Wikipedia page.

Below is an example, and you can also see it's output on ideone. Unfortunately, it does not work to specification as it does not properly implement weeks. The definition of the week number 01 in ISO-8601 is non-trivial and requires some browsing the calendar to determine where week one begins, and what exactly it means in terms of the number of days in the specified year. This can probably be fairly easily corrected (I'm just tired of playing with it).

function parseISODate (input) {
    var iso = /^(\d{4})(?:-?W(\d+)(?:-?(\d+)D?)?|(?:-(\d+))?-(\d+))(?:[T ](\d+):(\d+)(?::(\d+)(?:\.(\d+))?)?)?(?:Z(-?\d*))?$/;

    var parts = input.match(iso);

    if (parts == null) {
        throw new Error("Invalid Date");
    }

    var year = Number(parts[1]);

    if (typeof parts[2] != "undefined") {
        /* Convert weeks to days, months 0 */
        var weeks = Number(parts[2]) - 1;
        var days  = Number(parts[3]);

        if (typeof days == "undefined") {
            days = 0;
        }

        days += weeks * 7;

        var months = 0;
    }
    else {
        if (typeof parts[4] != "undefined") {
            var months = Number(parts[4]) - 1;
        }
        else {
            /* it's an ordinal date... */
            var months = 0;
        }

        var days   = Number(parts[5]);
    }

    if (typeof parts[6] != "undefined" &&
        typeof parts[7] != "undefined")
    {
        var hours        = Number(parts[6]);
        var minutes      = Number(parts[7]);

        if (typeof parts[8] != "undefined") {
            var seconds      = Number(parts[8]);

            if (typeof parts[9] != "undefined") {
                var fractional   = Number(parts[9]);
                var milliseconds = fractional / 100;
            }
            else {
                var milliseconds = 0
            }
        }
        else {
            var seconds      = 0;
            var milliseconds = 0;
        }
    }
    else {
        var hours        = 0;
        var minutes      = 0;
        var seconds      = 0;
        var fractional   = 0;
        var milliseconds = 0;
    }

    if (typeof parts[10] != "undefined") {
        /* Timezone adjustment, offset the minutes appropriately */
        var localzone = -(new Date().getTimezoneOffset());
        var timezone  = parts[10] * 60;

        minutes = Number(minutes) + (timezone - localzone);
    }

    return new Date(year, months, days, hours, minutes, seconds, milliseconds);
}

print(parseISODate("2010-06-29T15:33:00Z-7"))
print(parseISODate("2010-06-29 06:14Z"))
print(parseISODate("2010-06-29T06:14Z"))
print(parseISODate("2010-06-29T06:14:30.2034Z"))
print(parseISODate("2010-W26-2"))
print(parseISODate("2010-180"))