New Features in Node.js 18: An In-Depth Look

Introduction

Node.js 18 is the latest version of the popular asynchronous JavaScript runtime environment. It comes packed with useful new capabilities that enhance performance, improve modularity and enable more robust application development.

In this comprehensive guide, we’ll take a hands-on tour of some of the most notable features introduced in Node 18.

ECMAScript Modules Support by Default in Node.js 18

One of the biggest changes in Node.js 18 is that ECMAScript modules (ESM) are now supported by default.

ESM is the official standard format for packaging JavaScript code in a modular fashion. To use ESM in earlier versions of Node.js, we had to use .mjs file extensions and enable special flags.

But in Node 18, we can seamlessly import ESM modules using the standard .js file extension:

// math.js
export const PI = 3.14;

export function area(r) {
  return PI * r * r;
}

// app.js
import { PI, area } from './math.js';

console.log(area(3)); // 28.26

No more hassles with .mjs extensions or enable flags! We get native ESM support out of the box.

This is a big step forward in using standards-based modular JavaScript in Node.js.

Upgrade to V8 10.1 JavaScript Engine

Node 18 ships with the latest V8 JavaScript engine version – 10.1. This brings many notable performance enhancements and improvements:

1. Faster Object Destructuring

Destructuring and spreading objects is now faster:

// Destructuring gets speed boost
const { a, b } = obj;

// Object spread is faster too  
const newObj = {...obj};

2. Regular Expression Improvements

The RegExp engine has been upgraded with better compilation and execution performance.

3. Private Class Fields

V8 10.1 adds support for private brand checks on private fields in JavaScript classes.

4. Memory Optimizations

There are built-in memory usage optimizations across parsing, compiling and runtime execution.

5. Other Enhancements

• Faster in and instanceof operators
• Async stack trace support
• Better WebAssembly compilation

Together these V8 10.1 enhancements deliver measurable across-the-board speed ups. Our Node.js applications can benefit from the improved performance.

Native AbortSignal Support

AbortSignals provide a mechanism to programmatically cancel async operations like fetches, timeouts, intervals etc.

Node.js 18 provides native AbortController and AbortSignal APIs for the first time:

// Create controller and signal
const controller = new AbortController();
const signal = controller.signal;

// Pass signal to fetch  
fetch(url, { signal })
   .then(response => {
     // ...
   })

// Abort fetch request
controller.abort();

We can pass the AbortSignal to any async Node.js operation we want to be able to cancel. This brings new async flow control capabilities.

Timers Promises API

The timer functions like setTimeout, setInterval and setImmediate now return Promises when awaited:

// Timeout returns promise
const delay = await setTimeout(500); 

// Can await interval
await setInterval(() => {}, 1000);

This allows easier integration with async/await code flows.

ESM Module URL Access

We can now programmatically access the module URL in ESM using import.meta.url:

// module.js
import.meta.url; 
// file:///path/to/module.js

This exposes the fully resolved URL of the current ESM-based file.

importAssertions

Node.js 18 supports importAssertions which allows selectively importing parts of a module:

// Only import foo from lib.js
import foo from 'lib.js' assert {type: 'json'};

This prevents unnecessary code evaluation.

WHATWG URL Implementation

The legacy url module is now replaced with the more modern WHATWG URL API implementation:

const myURL = new URL('https://example.com/page?id=1');

myURL.pathname; // '/page'
myURL.search; // '?id=1'

Frequently Asked Questions

1. What are some of the major changes in Node.js 18?

Some key highlights of Node 18 are native ESM support, upgrading to V8 10.1, new AbortSignal API, Timer promises API, import.meta.url module access, and using the WHATWG URL library.

2. Does Node.js 18 have faster performance than previous versions?

Yes, Node.js 18 delivers noticeable performance improvements by upgrading the V8 engine to version 10.1. Operations like destructuring, regex usage, and spread syntax are now faster.

3. How can I use ECMAScript Modules in Node.js 18?

ECMAScript Modules are natively supported in Node 18 without any additional configuration. You can directly import/export ESM files using .js extensions instead of .mjs like before.

4. What benefits does the AbortSignal API provide?

The AbortSignal API allows canceling async actions like fetches or timeouts. This enables better control flow when working with promises and async operations.

5. Where can I find more documentation on changes in Node.js 18?

You can refer to the official Node 18 release notes at https://nodejs.org/en/blog/release/v18.0.0/ for detailed information on all additions and changes. The Node.js docs also cover the new APIs added.

Conclusion

So in summary, Node.js 18 delivers useful improvements like:

• Native ESM support without .mjs extensions
• V8 10.1 JavaScript engine upgrade
• AbortSignal for async flow control
• Timers Promises API
• ESM module URL access
• importAssertions
• WHATWG URL implementation

These features help build more modular, scalable and robust Node.js backends. The version lays the foundation for faster and more capable Node.js applications.