03.07.05
Form and Field Validation
Here’s a thought:
The only time a field in a web form needs to be perfectly formatted is when it’s going to be parsed by a computer system. If the field will likely never actually be used by a computer and the sub-parts will never have to be parsed, then let the user go hog wild with the formating.
Case in point: If a user is asked to enter their phone number, your server doesn’t care if it knows the which part is the area code, the local exchange or the last four digits. Let the user format those numbers anyway they want, as long as you get at least 10 digits (US) or 11 digits (US + International) or whatever the local number of digits needed are.