Javascript正则表达式分组问题

Question

I want to be able to detect/pick apart strings like :

tickets at entrance per person
ballons pp
tree planting

ie a description followed by an optional "pp" or "per person"

I try (.+)\\s+(per person|pp) and that works; but the pp|per person suffix is then not optional.

I try (.+)\\s+(per person|pp)? or (.+)\\s+(per person|pp){0,1} to make it optional, but then I get "undefined for the second capture group". Curiously the first capture group contains the "per":

matches: 0: (tickets at entrance per )
1: (tickets at entrance per)
2: (undefined)

(tested via http://www.regextester.com/ online regex tester)

What am I doing wrong with that second capture group ?

Answer 1

You can try this :

^(.+?)\s*(per person|pp|)$

You can read it like this :

Starts with  
 (any characters but at least one and not in greedy mode)
 any space-characters
 ("per person" or "pp" or nothing)
end