text_field_with_autocomplete and onKeyUp()

I have Rails 2.3 app with a text_field_with_autocomplete and I need to perform an action in the javascript onKeyUp() method. So, in effect, I believe i need to override this method. Does anyone know where this exists in the directory structure?

Unless the action has a timing relationship with whatever else is being done, you can just add an event listener to that field.

if I add the OnKeyUp() to that field though, it breaks the autocomplete.

Of course, you want to add the event handler "unobtrusively" -- in the head of the document or (better) in a separate file.