The codiqa developers might have a clue ;) http://blog.codiqa.com/2012/05/how-we-use-backbone-js-to-bui...

:) :) this just popped up on my Google Alerts. I built Codiqa, what do you want to know?

nice! I want to learn how to build a simple iphone/android emulator running on the web, which I can drag drop elements into.

Well, there are a lot of drag and drop libraries that can help you with basic DnD, I suggest starting there (for example, jQuery UI). After that it's a matter of positioning and rendering elements. It's really a deep topic, perhaps do some studying of an interface builder like Glade to see how they do certain things. For component object model stuff I really like AWT and Swing.