Node.js, the powerhouse of server-side JavaScript, undergoes regular six-monthly major releases, each bringing a plethora of enhancements and innovations. The latest iteration, Node.js 21, released on October 17, 2023, has stepped into the limelight with seven remarkable features. Let's delve into each of them, understand their significance, and explore how to leverage these new capabilities.
Keeping Up with Node.js 21: Getting Started
Before we jump into the exciting features, let's ensure we're on the right Node.js version using the Node Version Manager (NVM). Install Node.js 21 with the following commands:
bash
% nvm install 21
% nvm use 21
Verify the installation:
bash
% node -v
v21.1.0
Now that we're equipped let's explore the standout features.
1. Experimental Flag: Specifying Module Default
In Node.js 21, a groundbreaking experimental flag --experimental-default-type is introduced to specify the module default. Previously, CommonJS (CJS) was the default for Node.js, but with this flag, you can now opt for ES modules (ESM) as the default. For example:
javascript
// index.js
export const message = 'Hello, World!';
console.log(message);
Run the file as an ES module:
bash
% node --experimental-default-type=module index.js
Hello, World!
This new flag opens up possibilities for seamlessly integrating ES modules into your Node.js projects.
2. WebSocket Client Support
Node.js 21 introduces native support for WebSocket clients through the --experimental-websocket flag. This brings the power of full-duplex communication channels over a single TCP connection to Node.js. Let's explore a simple WebSocket client connecting to Postman's WebSocket echo service:
javascript
// client.js
const ws = new WebSocket('wss://ws.postman-echo.com/raw');
ws.addEventListener('message', (event) => {
console.log('Received:', event.data);
});
ws.addEventListener('open', () => {
let i = 0;
setInterval(() => {
const text = Message ${i++};
console.log('Sent:', text);
ws.send(text);
}, 1000);
});
Run the client with:
bash
% node --experimental-websocket client.js
Now, you can seamlessly integrate WebSocket communication into your Node.js applications.
3. Test Runner Concurrency Level Flag
In Node.js 21, testing becomes more efficient with the introduction of the --test-concurrency flag. This flag lets you control the maximum number of test files executed concurrently. For instance:
bash
% node --test --test-concurrency=2
Adjust the concurrency level to optimize your test suite's execution.
4. Test Runner Supports Passing Globs
Enhancing the testing capabilities further, Node.js 21 now supports specifying filenames using globs. This means you can conveniently run tests based on patterns. For example:
bash
% node --test **/test*.js
This simplifies test execution, especially in projects with a large number of test files.
5. File System Write with Flush Option
Node.js 21 introduces a handy flush option to the fs.writeFile() function. By setting flush to true, data is immediately flushed to permanent storage, preventing stale data issues. Here's a quick example:
javascript
// write.js
import { writeFile } from 'node:fs/promises';
import { Buffer } from 'node:buffer';
const data = new Uint8Array(Buffer.from('Hello, World!'));
await writeFile('message.txt', data, { flush: true });
Now, your data is guaranteed to be flushed promptly, ensuring data consistency.
6. Stable Fetch and WebStreams
Node.js 21 marks the stabilization of the fetch API and WebStreams. The fetch API simplifies network resource fetching, while WebStreams allow efficient handling of streamed data. This stabilization ensures a reliable foundation for working with these crucial functionalities.
7. Update to V8 JavaScript Engine 11.8
Keeping Node.js at the forefront of JavaScript innovation, version 21 updates the V8 JavaScript engine to version 11.8. This update introduces features like ArrayBuffer.prototype.transfer and ArrayBuffer.prototype.transferToFixedLength. These additions provide more flexibility and control over ArrayBuffer instances.
Embracing the Future with Node.js 21
Node.js 21 ushers in a wave of new features, empowering developers to build more robust, efficient, and feature-rich applications. Whether you're excited about ES module defaults, WebSocket communication, enhanced testing, or the latest V8 features, Node.js 21 has something for everyone. As you embark on your Node.js journey, don't forget to explore these features and elevate your development experience. Remember, Node.js 21 is the current release, but who knows what innovations Node.js 22 might bring in the next cycle of releases!
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