If they have a diffing algorithm patented that’s used in React, I can’t find it. Someone send it over!

A patent application must be filed within one year from public disclosure or it is barred. Unless Facebook has a continuing patent application that claims priority or they’re in a particulary arduous prosecution with the USPTO (in which case the application would still be published and public), the patent ship sailed long ago. Public disclosure includes incorporating the invention as a part of a larger whole. So the patentability clock started as soon as Facebook developed the algorithm and used it in any product. For example, I worked with a motion picture studio that sought to patent an animation technique. However, they were barred because that animation technique was used in a movie (public disclosure) more than a year prior despite not publicly revealing the technique.

The other major hurdles for patentability are novelty and non-obviousness (I hate that term). The novelty bar is objective and typically easy to hurdle — has this been done before?

The non-obviousness requirement, though, is very subjective and mushy: In light of the prior art, is the claimed invention obvious? This question, predictably, sends patent examination far into the weeds.

I’m not an expert in patenting diffing algorithims, and I doubt that anyone is. But from a common sense perspective, it’s hard to imagine that given the entire world of computer science, there is any patentable, non-obvious improvements to diffing.