How do I set a regexp with optional "(" and ")" that requires both when used?

Question

I need to create a reg expression that validates US phone numbers. The country code is optional as well as parenthesis around the area code. So far I have this

/^[1]?[-. ]?\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/

it works, however it will allow submissions like

1 555) 555 5555

and

1 (555 555 5555

I need to somehow tell the expression that () are optional but if a user uses one they have to close it off properly as well. How this could be done?

Maybe this can help stackoverflow.com/a/9776278/4040563

Zakher Masri
– Zakher Masri

2018-05-22 23:26:15 +00:00
Commented May 22, 2018 at 23:26 — Zakher Masri
– Zakher Masri, Commented May 22, 2018 at 23:26

revo · Accepted Answer · 2018-05-22 23:25:28Z

4

You have to work with branches:

^1?[-. ]?(?:\((\d{3})\)|(\d{3}))[-. ]?(\d{3})[-. ]?(\d{4})$
            ^^^^^^^^^^^^^^^^^^^

First side of alternation goes with a pair of parentheses and the other side with digits only. This way it doesn't allow unbalanced parentheses to take place.

Live demo

answered May 22, 2018 at 23:25

revo

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