jQuery/javascript help on form field validation

Hi,
This is a question for jquery/javascript expert.

I am looking for the function that validate the forms on the Register page. It may be an javascript code or jquery code, that runs only on the register page to check to evry field is filled during regsitration.

Where is the code ? I can’t find them in page-register.php. Are they part of the core jquery ?

The thing is, I am using the register/login form on a modal. I’m using the same code from that page. I need to do some experiment with the form field and the validation of forms.

Where is that code ?