why should I choose Scriptacolous and Prototype over the other frameworks like Dojo. I'm currently using Dojo and there's a lot to improve (especially documentation is rare), but it has a great user community.
What are the benefits and is there an equal user community helping each other?
Speaking personally, I chose to write about P & S because they were the libraries that I was using in production, and I like to know what I'm talking about! Seriously, I try to write from experience, and I picked on P & S as a bookj topic because I felt that using them had changed the way I code, and I wanted to share that new perspective.
Scriptaculous too takes a sensible approach to the UI, using JS to add behaviour to the DOM, working _with_ CSS, HTML, DOM etc. rather than trying to go over-the-top in OO terms.
There's a very active community around P & S, at the rails-spinoffs google group. (Plenty of rails developers are there, but also PHP, Java, .NET and other sorts, don't be mislead by the name.)