What is the purpose of the passive (non-capturing) group in a Javascript regex?

Question

What is the purpose of the passive group in a Javascript regex?

The passive group is prefaced by a question mark colon: (?:group)

In other words

Answer 1

Use them when you need a conditional and don't care about which of the choices cause the match.

Non-capturing groups can simplify the result of matching a complex expression. Here, the group 1 is always the name speaker. Without the non-capturing group, the speaker's name may end up in group 1 or group 2.

/hello (?:world|foobar )?said (.+)/