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JavaScript Regular Expressions in JavaScript Reformatting User Input A Better Telephone Number Validator

I agree with the previously asked question. The regex in the video does not work in regexPal or in app.js

/^(\d{3})\s\d{3}-\d{4}$/ The above expression does not work in regexPal.com. In app.js it does not cause the field to automatically format the phone number. I've checked and double-checked that I've typed it exactly as shown in the video by Joel.

This code:

\ (?\d{3})?\s?\d{3}-?\s?\d{4}

...works with all of these sets:


123 456 7890



(123) 4567890

(123) 456 7890

(123) 456-7890

But it's messy. Hopefully the following videos explain how to clean it up.

3 Answers

Steven Parker
Steven Parker
218,636 Points

What I see in the video is a little different :point_right: /^\(\d{3}\)\s\d{3}-\d{4}$/

Note the backslashes before the parentheses. Without these, the parentheses are interpreted as grouping symbols instead being used to match actual characters.

The slashes are there in the JavaScript file. It still doesn't work, the phone field will not reformat anything entered.

Steven Parker
Steven Parker
218,636 Points

I confirmed the revised regex to work in regexpal. If you provide a link to a workspace snapshot we can take a look at it in your environment.

Félix Guérin
Félix Guérin
17,910 Points

I think you may have set the flags wrong. In the case of the video, were you're testing two strings of numbers on 2 different lines, you should use the m flag (multi-line).