Didn’t both of them start around the same time? React released close a year later but it reportedly had been running internally at Facebook for a couple years by then.
It’s also a relatively modest extension of decades of prior art so I think it might be more accurate to treat it as a formalization of that practice rather than implying it was foundational.
It’s also a relatively modest extension of decades of prior art so I think it might be more accurate to treat it as a formalization of that practice rather than implying it was foundational.