Sorry, should have been more specific. they might ask you if and how JS handles general threading concepts. The correct answer, as you alluded to, is that aside from web workers, JS is not multi-threaded. You could then talk about the challenges of creating complex applications in an asynchronous event driven structure.

In other words, as an interviewer I would ask about threading to filter out the "huh?" type applicants and give them a chance to talk about some of the nuances of working with JS.