I found this code in some website, and it works perfectly. It validates that the phone number is in one of these formats:
(123) 456-7890 or 123-456-7890
The problem is that my client (I don't know why, maybe client stuffs) wants to add another format, the ten numbers consecutively, something like this: 1234567890.
I'm using this regular expression,
First off, your format validator is obviously only appropriate for NANP (country code +1) numbers. Will your application be used by someone with a phone number from outside North America? If so, you don't want to prevent those people from entering a perfectly valid [international] number.
Secondly, your validation is incorrect. NANP numbers take the form
NXX NXX XXXX where
N is a digit 2-9 and
X is a digit 0-9. Additionally, area codes and exchanges may not take the form
N11 (end with two ones) to avoid confusion with special services except numbers in a non-geographic area code (800, 888, 877, 866, 855, 900) may have a
So, your regex will pass the number (123) 123 4566 even though that is not a valid phone number. You can fix that by replacing
Finally, I get the feeling you're validating user input in a web browser. Remember that client-side validation is only a convenience you provide to the user; you still need to validate all input (again) on the server.
TL;DR don't use a regular expression to validate complex real-world data like phone numbers or URLs. Use a specialized library.