Hello,
I work on the YUI team at Yahoo!, and have included my thoughts below
in the hopes that it might help your investigation.
Q1 - Would YUI complement a rails development? Or does it compete directly
with prototype/scriptaculous?
YUI has some functional overlap with p/s, but can exist on the same
page because it's namespaced like all responsible page citizens should
be. (Locally recreating "$" is trivial, of course.)
Q2 - From the point of view of rich client web interfaces would you
recommend looking into YUI, or just stick with
rails/prototype/scriptaculous?
+ YUI provides extensive documentation in many formats: complete API
documentation, extensive examples and tutorials, handy full-color
cheatsheets, and interaction matrices (for dragdrop and autocomplete)
+ YUI offers the exact lines of code powering scores of high-scale
yahoo products globally, and has a dedicated fulltime engineering team.
+ YUI benefits from Yahoo!'s teams of interaction designers, usability
experts, and user experience researchers.
+ YUI includes extensive Accessibility, Internationalization, and
Localization support.
+ YUI supports a wide range of browsers and OSs under our Graded
Browser Support philosophy:
http://developer.yahoo.com/yui/articles/gbs/gbs.html
+ YUI takes a lightweight a la carte approach, and ships with three
versions of each file, normal (commented for human readability), -min
(for production environments) and -debug (which can pipe info to
Firebug or YUI's Logger control.)
+ As mentioned, YUI's namespacing protects your code and facilitates
collaboration and mashups.
It's true that I am biased, but I think it is worth your time to take a
look and see for yourself. I hope the information above provides a
useful starting point for your consideration.
Thanks,
Nate
Nate Koechley
natek@yahoo-inc.com
YUI Team, Yahoo! Inc.