How to match, but not capture, part of a regex?
Solution 1:
The only way not to capture something is using look-around assertions:
(?<=123-)((apple|banana)(?=-456)|(?=456))
Because even with non-capturing groups (?:…) the whole regular expression captures their matched contents. But this regular expression matches only apple or banana if it’s preceded by 123- and followed by -456, or it matches the empty string if it’s preceded by 123- and followed by 456.
| Lookaround | Name | What it Does |
|---|---|---|
| (?=foo) | Lookahead | Asserts that what immediately FOLLOWS the current position in the string is foo |
| (?<=foo) | Lookbehind | Asserts that what immediately PRECEDES the current position in the string is foo |
| (?!foo) | Negative Lookahead | Asserts that what immediately FOLLOWS the current position in the string is NOT foo |
| (?<!foo) | Negative Lookbehind | Asserts that what immediately PRECEDES the current position in the string is NOT foo |
Solution 2:
Update: Thanks to Germán Rodríguez Herrera!
In javascript try: /123-(apple(?=-)|banana(?=-)|(?!-))-?456/
Remember that the result is in group 1
Debuggex Demo
Solution 3:
Try:
123-(?:(apple|banana|)-|)456
That will match apple, banana, or a blank string, and following it there will be a 0 or 1 hyphens. I was wrong about not having a need for a capturing group. Silly me.