I'm surprised nobody has mentioned Meteor yet. As far as I understand, developing for Meteor means having a single codebase that erases the distinction between

I'm surprised nobody has mentioned Meteor yet. As far as I understand, developing for Meteor means having a single codebase that erases the distinction between server and client. Your web pages become live views of the underlying controllers. Modifying state in one client automatically modifies it in another. And I'm pretty sure it supports hot-swapping. http://meteor.com/ http://meteor.com/