Learn What's New In NodeJs 21: A Complete Guide

Learn What’s New In NodeJs 21: A Complete Guide

Learn What's New In NodeJs 21: A Complete Guide

The year 2023 is nearly over. However, how can we say goodbye without discussing the most significant NodeJS updates?

Every Node.js developer finds themselves in their element at this time of year with the newest and most advanced Node.js releases. It’s also Node.js 21, the most recent version of Node JS.

Our current release line is Node.js 21, which supersedes Node.js 20, which is being moved to long-term support (LTS). Node.js 21 will be the “Current” release for the next six months, or until April 2024, in accordance with the release schedule.

Introduction to NodeJS 21

The most recent release in Node.js’s line of avant-garde releases, Node JS 21, is available now. Node.js 21 was released on October 17, 2023. The most recent version of NodeJS has a stable fetch API along with a number of other user-facing additions and numerous internal enhancements. Additionally, Node.js 20 has entered a long-term support release, meaning that developers may now use it with stability and support.

Because of its incredible functionality and adaptability, Node.js doesn’t need any introduction for seasoned backend engineers.

Therefore, you may install the most recent version of Node.js on your system or upgrade it in a few easy steps if you’re intending to upgrade your tech stack with Node.js 21.

Node.js 21’s primary feature is the addition of the fetch API. This introduces a standardized method for sending HTTP requests, enabling developers to streamline the procedure as a whole.

The good news is that NodeJS developers can send and manage HTTP requests and responses without depending on complicated code or third-party tools.

The detailed release schedule is available here. Actually, in this post, we’ll go over a few of the most notable internal enhancements that Node JS 21 offers. V8 to v11.8 is a notable change for dependencies. The roadmap contains the noteworthy updates for V8.

What’s New in Node.js 21?


The release of Node.js 21 was made possible by over 1153 commits since the release of Node.js 20. The successful release was a result of the efforts of numerous developers and bug-fixing jobs. Let’s examine the highlights and significant changes in Node JS 21.

New features and significant modifications in Node JS 21:

  1. Fetch API Promoted to Stable
  2. Experimental Support for WebSocket API
  3. New –experimental-default-type Flip Module
  4. New V8 JavaScript Engine Version V8 11.8
  5. Experimental Support for Better Default for ESM
  6. Add Flush Option to fs.writeFile() Functions
  7. Update on http Version 9.1.2
  8. Partial Navigator API Implementation

Fetch API Promoted to Stable

The Fetch API has been moved up to the stable version with Node.js 21. By allowing Web API in Node.js, actually simplifies the creation of JavaScript, which is used on both frontends and backends.

Experimental Support for WebSocket API

With Node 21, WebSocket API functionality is available in experimental mode. In fact, this allows you to use a Node.js application to connect to a WebSocket server without using any external packages.

Once you run the node –expertimental-websocket command, you can use the WebSocket feature. This solution adheres to the specs and makes use of the undici websocket.

This is a significant advance since it integrates WebSocket functionality natively into Node.js, enabling real-time, two-way interactive communication between the client and server. This makes it easier for you to develop NodeJS apps that operate in real time, such as chat applications, game applications, and live updates for websites. Thus, this may be the rationale behind choosing Node.js development.

Here’s an example of coding to help you grasp it:

const ws = new WebSocket(‘wss://echo.websocket.events/’)

ws.addEventListener(‘message’, (event) => {

console.log(‘received:’, event.data) // “echo.websocket.events sponsored by Lob.com”


ws.addEventListener(‘open’, () => {

let i = 0

setInterval(() => {

const text = `Hello! #${i} is your number`

console.log(‘sending:’, text)



}, 1000)


If you store this code in a file called example.js, you can run it with node –experimental-websocket example.js to connect to a WebSocket server, send messages to it, and get responses.

New –experimental-default-type Flip Module

With the new –experimental-default-type flag in Node.js 21, you can now simply specify how files are interpreted: as “commonjs” or as “module.”

What occurs when you use it with the module set to:

  • Node.js will interpret or deliver any code you enter as an ES module until you tell it otherwise.
  • The folder without a package (or any parent folder).Files with the.js extension or those without one will be recognized as ES modules by json.
  • If the package.json file is present but does not indicate which type of module to use, and the folder is not inside node_modules, then files with or without an extension (.js) are identified as ES modules.


  • If you use the –experimental-wasm-modules flag, any file without an extension that contains a specified Wasm header will be identified as a Wasm module.
  • The new technique for loading ES modules is applied right away. It is no longer possible to modify the way Node.js launches modules by using –require.

To put it briefly, this flag allows for more flexible handling of the Node.js module system, which facilitates the use of WebAssembly and ES modules while maintaining backward compatibility with CommonJS.

New V8 JavaScript Engine Version V8 11.8

Cross-platform interoperability is made possible by the environment that the V8 JavaScript engine provides for the execution of JavaScript code. Because of this, developers are no longer required to be concerned with platform attributes, such as the operating system (Linux, Windows, macOS) or the underlying hardware architecture (x64, Arm, or Power PC).

Red Hat’s Node.js team members maintain V8 on s390 and Power PC. They commit modifications once a week to keep V8 running on these systems.

Experimental Support for Better Default for ESM

The new –experimental-default-type options enable defaults that are better suited for a full ESM implementation. This maintains CommonJS compatibility while maintaining the project’s continuous attempts to improve the developer experience for ESM users. Some approaches, like automatically recognizing ESM when possible, are also being investigated in addition to the research’s determination of the optimal solutions for the ESM developer experience.

Add Flush Option to fs.writeFile() Functions

This change adds a flush option to the fs.writeFile family of Node.js functions. Using the flush option forces data to be flushed to permanent storage following a successful write transaction, preventing stale data from appearing during subsequent read operations.

Update on http Version 9.1.2

The HTTP parser may now activate more leniency flags thanks to the latest version, NodeJS 21. This facilitates communication between llhttp and other non-standard HTTP implementations.

However, if these leniency flags are enabled, apps are susceptible to request smuggling or poisoning attacks. Therefore, unless there is an extremely compelling reason to do so, it is strongly advised to avoid choosing this option.

You can use this flag to allow leniency flags: –http-insecure-parser

Partial Navigator API Implementation

The Navigator is frequently used in front-end configurations. In Node.js v21, Navigator.hardwareConcurrency is accessible. It’s probable that following versions will provide more Navigator APIs.

The Promotion of Node.js 20 to LTS

After being elevated to LTS, it’s recommended to utilize the most recent version of Node.js, which is Nodejs 21 starting next week.

Upgrading is a smart decision for NodeJS app development because Node.js releases feature enhancements and new functionalities on a regular basis.

We will showcase some of the new features that we have noticed in Node.js 20 here. Even while they aren’t quite new in Node.js 20, considering how quickly features are added back into the current Node.js release line, they are nevertheless notable for having landed since the last major version that was upgraded to LTS.

Here are some points to consider:

  • Robust Test-Runner
  • Version is necessary for WASI (Experimental), and a command line flag is no longer needed.
  • The Permission Model (Test)
  • Individually Executable Programs (Test)
  • Tracing the Channel in Test

Get Started with Node JS 21 Today!

Node.js 21’s most recent release includes several intriguing new capabilities to streamline and ease the development process. As a young web app development firm, we are therefore prepared to use Node.js 21 on our next projects. We are confident that NodeJS 21 will assist you in overcoming obstacles and bottlenecks encountered during development.

But we’ve got you covered if you run into any problems when installing NodeJS 21 on your system or if, as a business owner, you want to update your Node.js project to the newest version. You can share your needs with our Node.js experts by getting in touch with them.

However, if you are looking for a Node development company through which you can hire offshore developers, then you should check out Appic Softwares. We have an experienced team of Node developers who can help you with updates and migrations as well.

So, what are you waiting for?

Contact us now!

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