"Cleaner" Method of Regex Matching Character(s) Only If Other(s) is/are Present - Build a Telephone Number Validator

1

Hey everyone :wave:

I’m working on the Build a Telephone Number Validator project, and I came up with this regex to match valid US phone number formatting (with some kind help from the fCC forum):

const phoneRegex = /^1? ?(\(\d{3}\)|\d{3})( |-)?\d{3}( |-)?\d{4}$/;

The part

(\(\d{3}\)|\d{3})

matches three digits either alone or with both an opening paranthesis before them and a closing paranthesis after them.

This part (with the right anchors) would match 123 or (123) but not (123 or 123).

I’m wondering if there’s a “cleaner” (i.e. more efficient and generally applicable) way of achieving the same result: making a regex match a certain character or group of characters only if another character or group of characters is present.

Thank you!

2

sounds like you need to research ‘regex lookaheads or lookbehinds’
it is not covered in the curriculum right now.

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3

Good to know. Thanks!

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