Node.js 21 is Here: Explore the Exciting New Features and Improvements! 🚀
Tags: node, javascript, api, backend
Published: 2023-10-18 22:34:04

## It sounds like **Node.js 21** is bringing a host of exciting features and updates! Here’s a breakdown of the notable changes:

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## 1. Stable fetch/WebStreams
**Description**: The fetch and **WebStreams** modules have been marked as stable. This impacts WebStreams, FormData, Headers, Request, Response, and fetch.
**Contribution**: By Steven in #45684.

## 2. Built-in WebSocket client
**Description**: An experimental browser-compatible WebSocket implementation is included and can be enabled through the --experimental-websocket flag.
**Contribution**: By Khafra in #49830.

## 3. V8 11.8 Update
**Description**: The V8 JavaScript engine has been updated to version 11.8, introducing improved performance and new language features like Array grouping, ArrayBuffer.prototype.transfer, and WebAssembly extended-const expressions.
**Contribution**: By Michaël Zasso in #47251.

## 4. Support for globs in the Node.js test runner
**Description**: The test runner now supports glob expressions when specifying the --test parameter, allowing for more efficient and flexible test execution.
**Contribution**: By Moshe Atlow in #47653.

## 5. ESM: --experimental-default-type flag
**Description**: The new flag allows users to flip the default module system used by Node.js, offering more flexibility in handling ES modules and CommonJS.
**Contribution**: By Geoffrey Booth in #49869.

## 6. Module customization hook update
**Description**: The globalPreload hook has been removed, recommending the use of register and initialize instead for data and communication handling between threads.
**Contribution**: By Jacob Smith in #49144.

## 7. Add flush option to fs.writeFile function
**Description**: A new 'flush' option ensures data is immediately flushed to permanent storage, preventing subsequent read operations from accessing stale data.
**Contribution**: By Colin Ihrig in #50009.

## 8. Performance Enhancements
**Streams**: Optimizations led by Robert Nagy in #50012.
**HTTP**: Reduced overhead by combining write calls when uncorking the response, contributed by Robert Nagy in #50167.

## 9. llhttp 9.1.2 strict mode enforcement
**Description**: Enhanced code reliability and security with strict mode enabled by default and stricter requirements for data processing and transmission.

## 10. Navigator Object integration
**Description**: Introduction of the global navigator object for accessing hardware concurrency information.
**Contribution**: By Yagiz Nizipli in #47769.

## 11. Deprecations
**Runtime deprecate punycode**: By Yagiz Nizipli in #47202.
**Runtime deprecate promisify-ing a function returning a Promise**: By Antoine du Hamel in #49609.

## Call to Action
Users and developers are encouraged to test their applications and modules with Node.js 21 and provide feedback.
Note the End-of-Life of Node.js 16 and consider upgrading to Node.js 18 or 20.

## Conclusion
Node.js 21 marks a significant step forward, infusing new energy and capabilities into the **ecosystem**. With the integration of the updated **V8 JavaScript engine, stable fetch/WebStreams**, and an **experimental built-in WebSocket client**, developers are equipped with enhanced tools and features to build efficient and scalable applications. The **improvements in performance, security, and modularity** underscore the Node.js community's commitment to innovation and excellence. As we embrace these changes, the collaboration and feedback from developers worldwide will be instrumental in refining and optimizing Node.js for diverse and complex modern applications. Let’s embark on this journey together, exploring and leveraging the enriched environment that Node.js 21 promises to offer! 🚀💻✨