SproutCore is a framework for building applications in JavaScript with remarkably little amounts of code. It can help you build full “thick” client applications in the web browser that can create and modify data, often completely independent of your web server, communicating with your server via Ajax only when they need to save or load data. It is an HTML5 application framework for building responsive, desktop-caliber apps in any modern web browser, without plugins.
SproutCore applications are full-fledged programs, written in JavaScript. That JavaScript executes in your user’s browser, freeing up your servers (and server engineers) to focus on what’s most important in a cloud application: delivering users’ data as quickly and reliably as possible.
Demo: http://demo.sproutcore.com/sample_controls/
Source: http://www.sproutcore.com/demos/