javascript regex iso datetime
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.
For matching just ISO date, like 2017-09-22, you can use this regexp:
^\d{4}-([0]\d|1[0-2])-([0-2]\d|3[01])$
It will match any numeric year, any month specified by two digits in range 00-12 and any date specified by two digits in range 00-31
I reworked the top answer into something a bit more concise. Instead of writing out each of the three optional patterns, the elements are nested as optional statements.
/[+-]?\d{4}(-[01]\d(-[0-3]\d(T[0-2]\d:[0-5]\d:?([0-5]\d(\.\d+)?)?[+-][0-2]\d:[0-5]\dZ?)?)?)?/
I'm curious if there are downsides to this approach?
You can find tests for my suggested answer here: http://regexr.com/3e0lh
Here is a regular expression to check ISO 8601 date format including leap years and short-long months. To run this, you'll need to "ignore white-space". A compacted version without white-space is on regexlib: http://regexlib.com/REDetails.aspx?regexp_id=3344
There's more to ISO 8601 - this regex only cares for dates, but you can easily extend it to support time validation which is not that tricky.
Update: This works now with javascript (without lookbehinds)
^(?:
(?=
[02468][048]00
|[13579][26]00
|[0-9][0-9]0[48]
|[0-9][0-9][2468][048]
|[0-9][0-9][13579][26]
)
\d{4}
(?:
(-|)
(?:
(?:
00[1-9]
|0[1-9][0-9]
|[1-2][0-9][0-9]
|3[0-5][0-9]
|36[0-6]
)
|
(?:01|03|05|07|08|10|12)
(?:
\1
(?:0[1-9]|[12][0-9]|3[01])
)?
|
(?:04|06|09|11)
(?:
\1
(?:0[1-9]|[12][0-9]|30)
)?
|
02
(?:
\1
(?:0[1-9]|[12][0-9])
)?
|
W(?:0[1-9]|[1-4][0-9]|5[0-3])
(?:
\1
[1-7]
)?
)
)?
)$
|
^(?:
(?!
[02468][048]00
|[13579][26]00
|[0-9][0-9]0[48]
|[0-9][0-9][2468][048]
|[0-9][0-9][13579][26]
)
\d{4}
(?:
(-|)
(?:
(?:
00[1-9]
|0[1-9][0-9]
|[1-2][0-9][0-9]
|3[0-5][0-9]
|36[0-5]
)
|
(?:01|03|05|07|08|10|12)
(?:
\2
(?:0[1-9]|[12][0-9]|3[01])
)?
|
(?:04|06|09|11)
(?:
\2
(?:0[1-9]|[12][0-9]|30)
)?
|
(?:02)
(?:
\2
(?:0[1-9]|1[0-9]|2[0-8])
)?
|
W(?:0[1-9]|[1-4][0-9]|5[0-3])
(?:
\2
[1-7]
)?
)
)?
)$
To cater for time, add something like this to the mixture (from: http://underground.infovark.com/2008/07/22/iso-date-validation-regex/ ):
([T\s](([01]\d|2[0-3])((:?)[0-5]\d)?|24\:?00)?(\15([0-5]\d))?([zZ]|([\+-])([01]\d|2[0-3]):?([0-5]\d)?)?)?