Very usefull hack, thank you

Also thank you Code Monkey for tuning it up .-)

installed

Do you have a modified version that can check against a custom field instead of Username?

Each user has a customer field "IDNumber" that they are assigned before they can register for our forum. We want to prevent users from using the same "IDNumber" twice if they attempt to register a second time for the forum.

Has anyone an idea how to add an regexp to proof the new username?
I php i do something like: ^[0-9a-zA-Z\.\-_]+$
but i have no clue how to do this is js.