Node.js 12.x: What's New, Release History & EOL Status

What Is New in Node.js 12?

Faster async/await and Async Stack Traces

V8 7.4 rewrites the async/await implementation. In V8 6.x, awaiting a non-promise value inside an async function had unnecessary overhead. V8 7.4 makes this path almost as fast as sync code, which improves throughput in async-heavy Express/Koa route handlers noticeably.

Async stack traces now show the correct call chain through awaits, instead of stopping at the first await boundary. Debugging async errors in production finally shows the full path from the origin call.

Worker Threads Stabilized

worker_threads moves from experimental to a stable (but not fully stable) status in Node.js 12. You can run CPU-heavy tasks in separate threads with shared memory via SharedArrayBuffer.

import { Worker, isMainThread, workerData } from 'node:worker_threads';

if (isMainThread) {
  const worker = new Worker('./image-resize.js', { workerData: { path: './img.png' } });
  worker.on('message', (result) => console.log('Done:', result));
} else {
  // CPU-heavy work here, does not block the main event loop
}

llhttp HTTP Parser

Node.js 12 switches from the legacy http_parser (C) to llhttp as the default HTTP parser. llhttp is generated from TypeScript specification, making it maintainable and easier to validate for correctness. It is also strictly faster in benchmarks.

This should be transparent to most users. If you use custom HTTP parsers or raw TCP connections that depend on parser quirks, verify compatibility.

Startup Performance via V8 Code Cache

Node.js 12 generates V8 code cache at build time for built-in libraries. This cuts startup time significantly for small scripts and CLI tools -- a welcome improvement for developers who run short-lived scripts frequently.