[jQuery] [validate] Validation code in separate file, fails to work

Hello!
I am curious how I can add all the validation code in a separate file.
I have put the code in a javascript file then included it.
Only it ain't working then. Do I need to do something special for this work?
I have like this in the file:
$(document).ready(function() {
var validator = ....more_code_here...
}
and then I include in the normal way in the HTML document
Yours,
Weyert