There is not really much information available for Alloy UI (the current JavaScript framework for Liferay 6.x), and as it builds on top of YUI, is it enough to get a book for YUI and scan through their documentation?
Somehow I'm not able to find any books or resources (plugins, except the one from the Liferay page), or is it just too new?
The Alloy UI is quite new, but you should be fine when learning the YUI library. As you will see, they are quite equal