The Node.js 23 version brings numerous new features and improvements to developers. Let's take an in-depth look at these changes and showcase how to use these new features through practical code examples.

Built-in WebSocket Client API

Node.js 23 now has a built-in WebSocket client API, eliminating the need to use third-party libraries. This significantly simplifies the use of WebSocket.

Example code:

// Code interpretation
const WebSocket = require("node:ws");
const ws = new WebSocket("ws://example.com:8080");
ws.on("open", function open() {
  console.log("Connection established");
  ws.send("Hello, server!");
});
ws.on("message", function incoming(data) {
  console.log("Received message:", data.toString());
});
ws.on("close", function close() {
  console.log("Connection closed");
});

Web Streams API

Node.js 23 introduces the Web Streams API, making it more convenient to handle stream data.

Example code:

// Code interpretation
const { ReadableStream, WritableStream, TransformStream } = require("node:stream/web");
const readableStream = new ReadableStream({
  start(controller) {
    controller.enqueue("Hello");
    controller.enqueue("World");
    controller.close();
  },
});
const transformStream = new TransformStream({
  transform(chunk, controller) {
    controller.enqueue(chunk.toUpperCase());
  },
});
const writableStream = new WritableStream({
  write(chunk) {
    console.log(chunk);
  },
});
readableStream.pipeThrough(transformStream).pipeTo(writableStream);

Global Blob and BroadcastChannel API

The Blob and BroadcastChannel APIs can now be used globally.

Blob example:

// Code interpretation
const blob = new Blob(["Hello, World!"], { type: "text/plain" });
const text = await blob.text();
console.log(text); // Output: Hello, World!

BroadcastChannel example:

// Code interpretation
const channel = new BroadcastChannel("test_channel");
channel.postMessage("Hello, channel!");
channel.onmessage = (event) => {
  console.log("Received message:", event.data);
};

Native ESM Support

Node.js 23 further enhances support for ECMAScript modules (ESM).

Example code (math.mjs):

// Code interpretation
export function add(a, b) {
  return a + b;
}
export function multiply(a, b) {
  return a * b;
}

Using the module (main.mjs):

// Code interpretation
import { add, multiply } from "./math.mjs";
console.log(add(5, 3)); // Output: 8
console.log(multiply(4, 2)); // Output: 8

Experimental TypeScript Stripping

Node.js 23 introduces the experimental TypeScript stripping feature, allowing you to run TypeScript files directly.

Example code (hello.ts):

// Code interpretation
function greet(name: string): string {
  return `Hello, ${name}!`;
}
console.log(greet("Zhang San"));

Running command:

# Code interpretation
node --experimental-strip-types hello.ts

Built-in File Watching

Node.js 23 has a built-in file-watching feature, eliminating the need to use third-party tools like nodemon.

Example code (app.js):

// Code interpretation
console.log("Server is running...");
// Simulate server logic
setInterval(() => {
  console.log("Processing requests...");
}, 2000);

Running command:

# Code interpretation
node --watch app.js

Now, whenever you modify the app.js file, Node.js will automatically restart the application.

Native Environment Variable Support

Node.js 23 supports directly loading.env files without the need for libraries like dotenv.

Example.env file:

# Code interpretation
DB_HOST=localhost
DB_USER=root
DB_PASS=password123

Example code (config.js):

// Code interpretation
console.log(process.env.DB_HOST);
console.log(process.env.DB_USER);
console.log(process.env.DB_PASS);

Running command:

# Code interpretation
node --env-file=.env config.js

Test Runner Module

Node.js 23 introduces the experimental node:test module, facilitating the creation and running of JavaScript tests.

Example code (test.js):

// Code interpretation
const test = require("node:test");
const assert = require("node:assert");
test("Simple addition test", (t) => {
  assert.strictEqual(1 + 2, 3);
});
test("Asynchronous test", async (t) => {
  const result = await Promise.resolve(42);
  assert.strictEqual(result, 42);
});

Running tests:

# Code interpretation
node --test test.js

These new features and improvements make Node.js 23 a more powerful and user-friendly JavaScript runtime environment. Through these practical code examples, developers can better understand and utilize these new functions, improving development efficiency and code quality.