Question

I want a very simple Regex for Javascript validation of phone number, which allows 10 digits and checks min numbers should be 10 and max 12 including - dash two times for ex. 123-123-1234

I have found some on internet, but none of them is working for min / max length.

Looking forward for quick response here.

Thanks !

Answer 1

You could do this

/^(?!.*-.*-.*-)(?=(?:\d{8,10}$)|(?:(?=.{9,11}$)[^-]*-[^-]*$)|(?:(?=.{10,12}$)[^-]*-[^-]*-[^-]*$)  )[\d-]+$/

See it here on Regexr

(?!...) is a negative lookahead assertion

(?=...) is a positive lookahead assertion

^                                          # Start of the string
    (?!.*-.*-.*-)                          # Fails if there are more than 2 dashes
    (?=(?:\d{8,10}$)                   # if only digits to the end, then length 8 to 10
        |(?:(?=.{9,11}$)[^-]*-[^-]*$)  # if one dash, then length from 9 to 11
        |(?:(?=.{10,12}$)
            [^-]*-[^-]*-[^-]*$         # if two dashes, then length from 10 to 12
         )
    )
[\d-]+                                     # match digits and dashes (your rules are done by the assertions)
$                                          # the end of the string