Here is a prior art reference by erichocean: https://news.ycombinator.com/item?id=14784983 "To anyone concerned about React's virtual DOM and diff'ing stuff, and a potential Facebook patent thereof, in early 2012 I wrote and published (under a GLPv3 license) a virtual DOM implementation with efficient diff'ing when I forked SproutCore[0] to become Blossom.[1]"