jQuery like image swap in YUI

Im trying to replicate a simple hover effect in YUI just like you would with jQuery however its a little confus开发者_StackOverflow社区ing. As in jquery it would go:

$('.hoverclass').hover(function() {
  $(this).addClass('up');
}, function() {
  $(this).removeClass('up');
});

Any pointers how to do it in YUI?

Thanks.

Why do you even need JS for this. Can't you just use CSS for this?

Well anyway check the source for this sample from Edwart Visser

YUI Hover

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YUI Hover JS (there is some other code in it for yui module detecion, skip to this comment /* HOVER CODE */)