Yes, you were interviewed by morons. Consider that bullet dodged. They were probably thinking of jQuery, which you probably should learn, but it does in fact use CSS selectors and xpath... (whatever you call xpath statements/selector thingies) for syntax. The right answer if you should want to be hired by somebody who makes the same mistake again is "JavaScript doesn't have selectors. Are you talking about jQuery? Or are you referring to the DOM API?" The DOM API, btw, is something you should already know if you don't.
Edit: Okay, maybe not total morons. They could have been thinking of the query selector API (see Dystroy's answer) but IMO, that still should have been clear.