Observables and "computed" values are something that every modern framework provides in some fashion. Frameworks that have explicit observables and computed values (Ember, Knockout, CanJS, etc) can provide high performance updates and, in my opinion, a more natural development experience.
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Design 
A team with both designers and developers needs a simple resource to share a project's styles and best practices. DocumentCSS generates a Live Style Guide so style documentation evolves along with the project. This project was built with the belief that a united team goal does not change the needs of individual roles. Whether you're an engineer, a designer, or somewhere in-between: we're building this for you.
The Bitovi Team
Bitovi
StealJS 0.10.0 just landed with a new feature that could change the way you develop: live-reload. Live-reload is an extension for Steal that speeds up development by eliminating the need to ever refresh your browser. It does this by intelligently reloading modules that become stale as you change your code. This technique is also known as "hot swapping" of modules. Steal doesn't refresh the page, but only re-imports modules that are marked as dirty. The result is a blazing fast development experience. See live-reload in action:
The Bitovi Team