Uh... name one toolkit or platform or library that became incompatible with the JS engines after a couple of years? JS inherits the Web property of extreme back

Uh... name one toolkit or platform or library that became incompatible with the JS engines after a couple of years? JS inherits the Web property of extreme backwards-compatibility. Breakages do happen, but they're extraordinarily rare. Unless you mean something different by compatibility? Sure, you won't be able to mix wildly different versions of libraries because their APIs change. But I wouldn't call that a "runtime environment".