How to match, but not capture, part of a regex?

Question

I have a list of strings. Some of them are of the form 123-...456. The variable portion \"...\" may be:

• the string \"apple\" followed by a hyphen,

Answer 1

Update: Thanks to Germán Rodríguez Herrera!

In javascript try: /123-(apple(?=-)|banana(?=-)|(?!-))-?456/

Remember that the result is in group 1

Debuggex Demo