Edit: Ok, I get it. Now we can add this behavior to arbitrary template engines or reactive frameworks, like Meteor for example. Thats awesome.
This appears to be just 43kb: https://github.com/Matt-Esch/virtual-dom/blob/master/dist/vi...
Whereas Facebook react 0.13.1 (without addons) weighs in at 599kb, or 121kb minified.
Note that I know almost nothing about this project. It may do less than React, be slower, etc... But if it does a half decent job with far less code then it's very compelling.
Last time I looked the prices offered for grabbing one I was schocked with extraordinary high costs for one domain.
edit: why downvotes?
But this one comes without Facebooks patent clauses.
Edit: Apparently that was too terse: While Facebooks React comes as BSD, the patents clauses are so broad that questioning software patents in a blog post would result in licence revocation. They are not just litigation defense like the ones from the Apache Foundation:
"The license granted hereunder will terminate, automatically and without notice, for anyone that makes any claim [...] alleging [...] that any right in any patent claim of Facebook is invalid or unenforceable."