Castro Roy Castro Roy - 1 month ago 24
Javascript Question

Validate phone number with JavaScript

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,

/^(\()?\d{3}(\))?(-|\s)?\d{3}(-|\s)\d{4}$/


How can I add that it also validates the another format? I'm not good with regular expressions.

Answer

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 N11 exchange.

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 \d{3} with [2-9]{1}\d{2}.

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.

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