What’s New in Node.js 10 LTS? Key Features, Deprecations, and Experimental APIs

Preface

After more than a year of development, Node.js 10 has finally entered LTS. This article outlines the noteworthy features.

LTS stands for Long Term Support, a reliable version for production environments.

The Alibaba Cloud Alinode team has quickly added support for the new version; updating to alinode-v4.5.0 lets developers using the Node.js performance platform enjoy the new features.

See the documentation for the detailed version mapping.

TLDR

, main keywords:

HTTP/2

BigInt

Window installer optimization

– solves native module compilation issues Work Threads – experimental API new Buffer() – constructor API fully deprecated

New Features

The following new features are provided by default in Node.js 10 LTS without any flags.

HTTP/2

Native support for HTTP/2 brings more efficient network utilization, header compression, multiplexed streams, and Server Push, enabling better user experiences especially for first‑page static asset optimization.

BigInt

JavaScript’s Number type is limited to safe integers between -2^53 and 2^53 and cannot precisely represent many decimals. The TC39 proposal BigInt (Stage 3) is now partially implemented in Node.js 10, allowing precise handling of large integers.

Recursive fs.mkdir and fs.mkdirSync

Previously these APIs mirrored the Linux mkdir command but lacked the -p recursive option, requiring developers to use external modules like mkdirp. The new recursive option adds native recursive directory creation:

fs.mkdirSync('/home/admin/aaa/bbb/ccc', { recursive: true });

CLI Flag Auto‑Completion

Node’s command‑line flags can now be auto‑completed in Bash. Enable it with:

$ node --completion-bash > node_bash_completion
$ source node_bash_completion

After sourcing, typing node -- and pressing TAB will suggest available flags. Implemented in PR 20713.

Windows Installer Optimization

The MSI installer now includes an optional component “Install Node.js native compilation toolset”, greatly reducing the difficulty of compiling native modules on Windows and lowering the entry barrier for Windows developers.

Code Coverage

Node now exposes V8’s native coverage capabilities via the NODE_V8_COVERAGE environment variable, simplifying high‑quality test coverage collection without the overhead of external tools like Istanbul.

Deprecated Features

The following APIs are permanently deprecated in Node.js 10 LTS; projects should migrate before upgrading.

new Buffer()

The direct Buffer constructor is removed. Use the safer alternatives:

Buffer.from()

Buffer.alloc()

Buffer.allocUnsafe()

Experimental APIs

These APIs are at stability 1: Experimental and may change or be removed. Do not use them in production.

fs.promises

Promise‑based versions of all fs methods are available under fs.promises. Example usage:

(async () => {
  const fs = require('fs');
  const { promisify } = require('util');
  const readFile = promisify(fs.readFile);
  let content = await readFile('package.json');
  console.log(content.toString());

  const mz = require('mz');
  content = await mz.fs.readFile('package.json');
  console.log(content.toString());

  const fsPromise = require('fs').promises;
  content = await fsPromise.readFile('package.json');
  console.log(content.toString());
})();

Worker Threads

The highly requested Worker Threads API is introduced as an experimental feature (requires the --experimental-worker flag) to improve performance of CPU‑intensive tasks.

const { Worker, isMainThread, parentPort, workerData } = require('worker_threads');
if (isMainThread) {
  module.exports = async function parseJSAsync(script) {
    return new Promise((resolve, reject) => {
      const worker = new Worker(__filename, { workerData: script });
      worker.on('message', resolve);
      worker.on('error', reject);
      worker.on('exit', (code) => {
        if (code !== 0) reject(new Error(`Worker stopped with exit code ${code}`));
      });
    });
  };
} else {
  const { parse } = require('some-js-parsing-library');
  const script = workerData;
  parentPort.postMessage(parse(script));
}

This API is still being evaluated by the core team; feedback is welcome.

Other Minor Updates

These items may be less relevant to most developers but are listed for completeness.

OpenSSL 1.1.0i

Node now supports [email protected] , which adds ChaCha20‑Poly1305 encryption.

PEM‑Level Encryption Support

Node now supports PEM‑level encryption as defined in RFC 1421, a format originally used for secure email and now widely adopted.

References

What’s New to LTS with Node.js 10 LTS

Node.js ChangeLog

Rethinking JavaScript Test Coverage: https://medium.com/the-node-js-collection/rethinking-javascript-test-coverage-5726fb272949

coverage: expose native V8 coverage by bcoe · Pull Request #22527 · nodejs/node

Node.js Buffer documentation: https://nodejs.org/api/buffer.html#buffer_buffer_from_buffer_alloc_and_buffer_allocunsafe

ChaCha20‑Poly1305: https://tools.ietf.org/html/rfc7539

RFC 1421: https://tools.ietf.org/html/rfc1421