V8 is a JIT compiler that uses the Ignition [1] interpreter and only compiles sections of code down to machine instructions once they've been marked as hot via

V8 is a JIT compiler that uses the Ignition [1] interpreter and only compiles sections of code down to machine instructions once they've been marked as hot via TurboFan [2]. V8 can also go back and forth from machine instructions back to bytecode if it identifies that certain optimization assumptions no longer hold. [1] https://v8.dev/docs/ignition https://v8.dev/docs/ignition [2] https://v8.dev/docs/turbofan https://v8.dev/docs/turbofan