What is the V8 engine in Node.js?

Direct answer

V8 is Google's open-source JavaScript engine that compiles JS to native machine code — Node embeds V8 to execute your scripts; Node version bumps often ship a newer V8 with language features and performance fixes.

Why interviewers ask this

They check whether you know Node is V8 plus native bindings, not a custom interpreter — and whether you can link Node version to supported ECMAScript features.

JIT compilation — Ignition interpreter + TurboFan optimizer hot-path code for speed.
Garbage collection — generational GC frees unused objects; long-lived caches cause heap growth (Q72).
Node ↔ V8 mapping — node -p process.versions shows v8 string; LTS tracks stable V8 branch.

v8-versions.js

console.log({
  node: process.version,
  v8: process.versions.v8,
  modules: process.versions.modules,
});

// Feature availability follows V8 in your Node version
// e.g. native ESM, top-level await, structuredClone