regex101: ISO 8601 date

^start of line

Group 1(\d{4}(-?\d\d){2})

\d{4}a Unicode decimal digit, repeated exactly 4 times

Group 2(-?\d\d){2}

{2}repeats the group contents below exactly 2 times:

-?optionally matches the literal - (45₁₀ / 55₈ / 2D₁₆)

\da Unicode decimal digit

Character Class[tT]?

?matches at most one character from the set below:

tthe literal t (116₁₀ / 164₈ / 74₁₆) (case sensitive)

Tthe literal T (84₁₀ / 124₈ / 54₁₆) (case sensitive)

Group 3((\d\d:?){1,2}(\d\d)?(.\d{3})?([zZ]|[+-](\d\d):?(\d\d)))?

?repeats the group contents below at most once:

Group 4(\d\d:?){1,2}

{1,2}repeats the group contents below between 1 and 2 times:

\da Unicode decimal digit

:?optionally matches the literal : (58₁₀ / 72₈ / 3A₁₆)

Group 5(\d\d)?

?repeats the group contents below at most once:

\da Unicode decimal digit

Group 6(.\d{3})?

?repeats the group contents below at most once:

.any Unicode character (except for line terminators)

\d{3}a Unicode decimal digit, repeated exactly 3 times

Group 7([zZ]|[+-](\d\d):?(\d\d))

1st Alternative[zZ]

Character Class[zZ]

zthe literal z (122₁₀ / 172₈ / 7A₁₆) (case sensitive)

Zthe literal Z (90₁₀ / 132₈ / 5A₁₆) (case sensitive)

2nd Alternative[+-](\d\d):?(\d\d)

Character Class[+-]

+the literal + (43₁₀ / 53₈ / 2B₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 8(\d\d)

\da Unicode decimal digit

:?optionally matches the literal : (58₁₀ / 72₈ / 3A₁₆)

Group 9(\d\d)

\da Unicode decimal digit

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

^(\d{4}(-?\d\d){2})[tT]?((\d\d:?){1,2}(\d\d)?(.\d{3})?([zZ]|[+-](\d\d):?(\d\d)))?$

Test String
New

2017-06-12T10:10:15.770Z
2017-06-12T10:10:15Z
2017-06-12T10:10Z
2017-06-12T101015.770Z
2017-06-12T101015Z
2017-06-12T1010Z
20170612T10:10:15.770Z
20170612T10:10:15Z
20170612T10:10Z
20170612T101015.770Z
20170612T101015Z
20170612T1010Z
20170612T10Z
2017-06-12
2017-06-12T
1994-11-05T08:15:30-05:00
2017-06-12T09:37:45+00:00
2017-06-12T09:37:45Z
20170612T093745Z

2017-06-12Z
2017-06-12TZ
2017-06-12T101015770Z
2017-06-12T009:307:405Z
2017-06-12T09.37.45Z
2017-0612T10:10:15.770Z
2017-0612T10:10:15Z
2017-0612T10:10Z
2017-0612T101015.770Z
2017-0612T101015Z
2017-0612T1010Z
2017-0612T10Z
201706-12T10:10:15.770Z
201706-12T10:10:15Z
201706-12T10:10Z
201706-12T101015.770Z
201706-12T101015Z
201706-12T1010Z
201706-12T10Z

MATCH

2009-12T12:34
2009
2009-05-19
2009-05-19
20090519
2009123
2009-05
2009-123
2009-222
2009-001
2009-W01-1
2009-W51-1
2009-W511
2009-W33
2009W511
2009-05-19
2009-05-19 00:00
2009-05-19 14
2009-05-19 14:31
2009-05-19 14:39:22
2009-05-19T14:39Z
2009-W21-2
2009-W21-2T01:22
2009-139
2009-05-19 14:39:22-06:00
2009-05-19 14:39:22+0600
2009-05-19 14:39:22-01
20090621T0545Z
2007-04-06T00:00
2007-04-05T24:00
2010-02-18T16:23:48.5
2010-02-18T16:23:48,444
2010-02-18T16:23:48,3-06:00
2010-02-18T16:23.4
2010-02-18T16:23,25
2010-02-18T16:23.33+0600
2010-02-18T16.23334444
2010-02-18T16,2283
2009-05-19 143922.500
2009-05-19 1439,55

DONT MATCH

200905
2009367
2009-
2007-04-05T24:50
2009-000
2009-M511
2009M511
2009-05-19T14a39r
2009-05-19T14:3924
2009-0519
2009-05-1914:39
2009-05-19 14:
2009-05-19r14:39
2009-05-19 14a39a22
200912-01
2009-05-19 14:39:22+06a00
2009-05-19 146922.500
2010-02-18T16.5:23.35:48
2010-02-18T16:23.35:48
2010-02-18T16:23.35:48.45
2009-05-19 14.5.44
2010-02-18T16:23.33.600
2010-02-18T16,25:23:48,444

Regular Expressions 101

Regular Expression

Test String
New

Substitution
Processing...

Regular Expression

Test StringNew

SubstitutionProcessing...

Test String
New

Substitution
Processing...