What is a javascript regular expression for matching time in military (24 hour) format?

Question

I would like a javascript regular expression that will match time using the 24 hour clock, where the time is given with or without the colon.

For example, I would like to match time in the following formats:

"0800", "23:45", "2345"

but that would not match invalid times such as

"34:68" or "5672"

Answer 1

/^(?:[01]\d|2[0-3]):?[0-5]\d$/

Answer 2

/(00|01|02|03|04|05|06|07|08|09|10|11|12|13|14|15|16|17|18|19|20|21|22|23):?(0|1|2|3|4|5)\d/

:)

Answer 3

I don't think regex is the right solution for this problem. Sure, it COULD be done, but it just seems wrong.

Make sure your string is four characters long, or 5 characters with a colon in the middle. Then, parse each side and make sure that the left side is less than 24 and the right hand is less than 60.

The regex solution is just so much more complicated.

Answer 4

This should do it:

^([01]\d|2[0-3]):?([0-5]\d)$

The expression reads:

^        Start of string (anchor)
(        begin capturing group
  [01]   a "0" or "1"
  \d     any digit
 |       or
  2[0-3] "2" followed by a character between 0 and 3 inclusive
)        end capturing group
:?       optional colon
(        start capturing
  [0-5]  character between 0 and 5
  \d     digit
)        end group
$        end of string anchor

Answer 5

To keep the colon optional and allow all valid times:

([01]\d|2[0-3]):?[0-5]\d

Note that this assumes midnight will always be 0000 and never 2400.

Answer 6

Here's a blog post, looking for the same thing and a bunch of potential answers -- most of which don't work, but there is good discussion as to why each fails.

Of course, explicitly long and accurate is always a possibility!

Answer 7

Remove the ':' if the string has one, then if the string is of the form "DDDD", convert it into an int and compare it to 2400.