Question

I have the following regular expression in JavaScript which matches strings like “12:23:34:45” and “12:23”

/^([0-9]{1,2}\:){0,3}([0-9]{0,2})?$/

The problem I have is that when I look at the match data there are only ever 3 matches returned. e.g. for 12:23:34:45 the matches returned are:

12:23:34:45
34:
45

i.e. the first capturing group only reports its last value. I would like the matches to be:

12:23:34:45
12:
23:
34:
45

Is this possible?

Answer 1

No, this is not possible in JavaScript (and most other regex flavors except Perl 6 and .NET). Repeated capturing groups always store the last value that was matched. Only .NET and Perl allow you to access those matches individually (match.Groups(i).Captures in .NET, for example).

You need two passes, the first to find the strings, the second to iterate over the matches and scan those for their sub-values.

Or make the regex explicit:

/^([0-9]{1,2}:)?([0-9]{1,2}:)?([0-9]{1,2}:)?([0-9]{0,2})?$/