[geuis]

Pro tip: Stay as far away from YUI as you can. YUI is painful to work with. Even after the changes that were done in the YUI3.x releases, it's still a nightmare. Syntax is awful and all of the various components you have to configure together are just more levels of bloat than you need.

People use jQuery + <insert other js frameworks> because they work better, are easier to use, are lightweight, and don't trap you into using the entire monolithic package that is offered by YUI.