JVM

The talk explains that AOT and JIT describe when compilation happens, not necessarily what language is compiled or what output it produces. Using Java and the JVM as examples, it shows that ahead-of-time compilation and just-in-time compilation can coexist in one system. Hermes moves JavaScript parsing and compilation, along with optimizations such as inlining and loop unrolling, to app build time, then executes the resulting bytecode at runtime. The speakers also discuss why Hermes removed an experimental JIT and how React Native developers enable Hermes.