What’s New in Node.js 20 — SitePoint | Digital Noch

Model 20 of Node.js was launched on 18 April 2023. It addresses some points and criticisms already “solved” by Deno and Bun, together with a new permission mannequin and a secure native take a look at runner. This text examines the brand new choices out there to builders utilizing the world’s most-used JavaScript runtime.


  1. The Node.js Launch Schedule
  2. New Permission Mannequin
  3. Native Take a look at Runner
  4. Compiling a Single Executable Software
  5. Up to date V8 JavaScript Engine
  6. Miscellaneous Updates

The Node.js Launch Schedule

Node.js has a six-month launch schedule:

  • The April even-numbered releases (14, 16, 18, and so on.) are secure and obtain long-term help (LTS) updates for 3 years.

  • The October odd-numbered launch (15, 17, 19, and so on.) are extra experimental and updates typically finish after one yr.

Normally, you need to go for the even-numbered LTS model except you require a selected function in an experimental launch and intend to improve later. That mentioned, Node.js 20 is new and the web site advises you proceed with model 18 whereas the event group fixes any late-breaking points.

Node.js 20 has the next new options …

New Permission Mannequin

Working node somescript.js isn’t with out danger. A script can do something: delete important information, ship personal information to a server, or run a cryptocurrency miner in a baby course of. It’s tough to ensure your individual code received’t break one thing: are you able to make certain that each one modules and their dependencies are secure?

The brand new (experimental) Node.js Permission Mannequin restricts what script can do. To make use of it, add the --experimental-permission flag your node command line adopted by:

  1. --allow-fs-read to grant read-access to information. You possibly can restrict read-access to:

    • particular directories: --allow-fs-read=/tmp/
    • particular information: --allow-fs-read=/residence/me/information.json
    • or wildcard file patterns: --allow-fs-read=/residence/me/*.json
  2. --allow-fs-write to grant write-access to information with equivalent listing, file, or wildcard patterns.

  3. --allow-child-process to allow youngster processes equivalent to executing different scripts maybe written in different languages.

  4. --allow-worker to allow employee threads, which execute Node.js code in parallel to the primary processing thread.

Within the following instance, somescript.js can learn information within the /residence/me/information/ listing:

node --experimental-permission --permit-fs-learn=/residence/me/information/ somescript.js

Any try to jot down a file, execute one other course of, or launch an internet employee raises a ERR_ACCESS_DENIED error.

You possibly can test permissions inside your utility utilizing the brand new course of.permission object. For instance, right here’s how one can test whether or not the script can write information:

course of.permission.has('fs.write');

Right here’s how one can test if the script can write to a selected file:

if ( !course of.permission.has('fs.write', '/residence/me/mydata.json') ) {
  console.error('Can not write to file');

JavaScript permission administration was first launched by Deno, which presents fine-grained management over entry to information, setting variables, working system data, time measurement, the community, dynamically-loaded libraries, and youngster processes. Node.js is insecure by default except you add the --experimental-permission flag. That is much less efficient, however ensures current scripts proceed to run with out modification.

Native Take a look at Runner

Traditionally, Node.js has been a minimal runtime so builders might select what instruments and modules they required. Working code assessments required a third-party module equivalent to Mocha, AVA, or Jest. Whereas this resulted in loads of decisions, it may be tough to make the greatest choice, and switching instruments is probably not simple.

Different runtimes took an alternate view and supplied built-in instruments thought of important for improvement. Deno, Bun, Go, and Rust all provide built-in take a look at runners. Builders have a default selection however can go for an alternate when their mission has particular necessities.

Node.js 18 launched an experimental take a look at runner which is now secure in model 20. There’s no want to put in a third-party module, and you’ll create take a look at scripts:

  • in your mission’s /take a look at/ listing
  • by naming the file take a look at.js, take a look at.mjs, or take a look at.cjs
  • utilizing test- at the start of the filename — equivalent to test-mycode.js
  • utilizing take a look at on the finish of the filename with previous interval (.), hyphen (-) or underscore (_) — equivalent to mycode-test.js, mycode_test.cjs, or mycode.take a look at.mjs

You possibly can then import node:take a look at and node:assert and write testing capabilities:

import { take a look at, mock } from 'node:take a look at';
import assert from 'node:assert';
import fs from 'node:fs';

take a look at('my first take a look at', (t) => {
  assert.strictEqual(1, 1);

take a look at('my second take a look at', (t) => {
  assert.strictEqual(1, 2);

mock.methodology(fs, 'readFile', async () => 'Node.js take a look at');
take a look at('my third take a look at', async (t) => {
  assert.strictEqual( await fs.readFile('anyfile'), 'Node.js take a look at' );

Run the assessments with node --test take a look at.mjs and study the output:

✔ my first take a look at (0.9792ms)
✖ my second take a look at (1.2304ms)
  AssertionError: Anticipated values to be strictly equal:

  1 !== 2

      at TestContext.<nameless> (take a look at.mjs:10:10)
      at Take a look at.runInAsyncScope (node:async_hooks:203:9)
      at Take a look at.run (node:inside/test_runner/take a look at:547:25)
      at Take a look at.processPendingSubtests (node:inside/test_runner/take a look at:300:27)
      at Take a look at.postRun (node:inside/test_runner/take a look at:637:19)
      at Take a look at.run (node:inside/test_runner/take a look at:575:10)
      at async startSubtest (node:inside/test_runner/harness:190:3) {
    generatedMessage: false,
    code: 'ERR_ASSERTION',
    precise: 1,
    anticipated: 2,
    operator: 'strictEqual'

✔ my third take a look at (0.1882ms)
ℹ assessments 3
ℹ go 2
ℹ fail 1
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 72.6767

You possibly can add a --watch flag to robotically re-run assessments when the file adjustments:

node --test --watch take a look at.mjs

You can even run all assessments discovered within the mission:

node --test

Native testing is a welcome addition to the Node.js runtime. There’s much less have to be taught totally different third-party APIs, and I not have an excuse when forgetting so as to add assessments to smaller tasks!

Compiling a Single Executable Software

Node.js tasks require the runtime to execute. This is usually a barrier when distributing purposes to platforms or customers who can’t simply set up or preserve Node.js.

Model 20 presents an experimental function which lets you create a single executable utility (SEA) that you may deploy with out dependencies. The guide explains the method, though it’s somewhat convoluted:

  1. You have to have a mission with a single entry script. It should use CommonJS quite than ES Modules.

  2. Create a JSON configuration file used to construct your script right into a blob which runs contained in the runtime. For instance, sea-config.json:

      "major": "myscript.js",
      "output": "sea-prep.blob"
  3. Generate the blob with node --experimental-sea-config sea-config.json.

  4. In keeping with your OS, you could then copy the node executable, take away the binary’s signature, inject the blob into the binary, re-sign it, and take a look at the ensuing utility.

Whereas it really works, you’re restricted to older CommonJS tasks and may solely goal the identical OS as you’re utilizing. It’s sure to enhance, given the superior Deno compiler can create an executable for any platform in a single command from JavaScript or TypeScript supply information.

You also needs to concentrate on the ensuing executable’s file measurement. A single console.log('Howdy World'); generates a file of 85MB, as a result of Node.js (and Deno) have to append the entire V8 JavaScript engine and customary libraries. Choices to scale back file sizes are being thought of, nevertheless it’s unlikely to go under 25MB.

Compilation received’t be sensible for small command-line instruments, nevertheless it’s a extra viable choice for bigger tasks equivalent to a full net server utility.

Up to date V8 JavaScript Engine

Node.js 20 contains the most recent model of the V8 engine, which incorporates the next JavaScript options:

Miscellaneous Updates

The next updates and enhancements are additionally out there:


Node.js 20 is a serious step ahead. It’s a extra important launch, and implements a few of Deno’s higher options.

Nonetheless, this begs the query: do you have to use Deno as a substitute?

Deno is nice. It’s secure, natively helps TypeScript, reduces improvement occasions, requires fewer instruments, and receives common updates. On the draw back, it’s been round much less time, has fewer modules, and so they’re typically shallower imitations of Node.js libraries.

Deno and Bun are value contemplating for brand new tasks, however there are millions of current Node.js purposes. Deno and Bun are making it simpler to transition code, however there received’t at all times be a transparent benefit for transferring away from Node.js.

The excellent news is we now have a thriving JavaScript ecosystem. The runtime groups are studying from one another and fast evolution advantages builders.

Related articles


Leave a reply

Please enter your comment!
Please enter your name here