Earlier quoted context omitted.
What's wrong with "element.onmouseover = fn", by the way?
In this way you can attach just one function to the event. Other way allows for more flexibility. http://www.quirksmode.org/js/events_tradmod.html http://www.quirksmode.org/js/events_advanced.html But I guess interviewer was not implying onmouseover was "wrong", just probing how much does candidate know about the topic.
Alright. To me it sounded a bit like onmouseover was used only by bad programmers.