I was also quite surprised that the javascript components seemed to take a step backwards in design and documentation from Foundation 3 to 4. Not sure why that is.
Except Bootstrap 2.x's JS was terribly basic and didn't play well with single page apps. I haven't tried v3 yet so I don't know if it has improved.
Re:Bootstrap 3 released
by sergiotapia on Tuesday August 20, 2013 @12:57PM
(#6244945)
I wouldn't know about that; I've never built a single page app.
I just removed it, and went back to Bootstrap.