From an interview to 280 Sliders developer, I learned to know that Cappuccino is the framework behind the product. And Objective-J language is introduced so they can port Apple’s Cocoa framework. Cocoa is a framework based on Apple’s own language Objective-C. In fact, 280 Slides’ UI looks like Apple’s Keynotes. And the 280 Sliders’ developers are former Apple developers. Cappuccino parses Objective-J files, which are with file extension .j, convert to JavaScript codes and executes them on the fly.

So, another cross compiler, Objective-C to JavaScript. It is quite worthy for further digging.

And digging into sources, I find that it uses lots of images to make up the whole UI, includes button, scrollbar, window borders and other components. And besides *.j and *.js files, there are some *.plist and *.sj files. *.sj use the same syntax as normal JavaScript. But from the sources, I guess they are compiled and mixed from *.j. Besides the core Objective-J.js, AppKit.sj, Foundation.sj and SlideKit.sj are three important files.

And it is great to hear the news that Cappuccino and Objective-J will be open-sourced at http://objective-j.org/ in the near future.