Question

I have a text box and it says “Phone:” as the standard here for phone number is (XXX)-XXX-XXXX
I’d like to have a javascript that automatically puts my numbers into that format if it’s not in that format, so if you typed 9993334444 then it would change it automatically on the fly as I’m typing to (999)-333-4444 I have looked around Google for Javascript Phone Regex to no success, maybe a Regex isn’t what I’m looking for?

Answer 1

you want to add an onkeyup event with a regex like

this.value = this.value.replace(/^\(?([0-9][0-9][0-9]){1}\)?-?([0-9][0-9][0-9][0-9]){1}-?([0-9][0-9][0-9]){1}$/, '($1)-$2-$3');

Check out http://jsfiddle.net/R8enX/

/ means start/end a regex string
^ means start of matching string
$ means end of matching string
? means 0 or 1 instances (make braces and dashes optional)
[0-9] means any single digit
(x){1} tags x as an expression that we can reference in the replacement with a $ sign

EDIT: realized I missed a digit on the last group of numbers, the jsfiddle will only work (properly) with 3 digits in the last group