About Node.js®

As an asynchronous event-driven JavaScript runtime, Node.js is designed to build scalable network applications. In the following "hello world" example, many connections can be handled concurrently. Upon each connection, the callback is fired, but if there is no work to be done, Node.js will sleep.

const { createServer } = require('node:http');

const hostname = '127.0.0.1';
const port = 3000;

const server = createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World');
});

server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

JavaScript

This is in contrast to today's more common concurrency model, in which OS threads are employed. Thread-based networking is relatively inefficient and very difficult to use. Furthermore, users of Node.js are free from worries of dead-locking the process, since there are no locks. Almost no function in Node.js directly performs I/O, so the process never blocks except when the I/O is performed using synchronous methods of Node.js standard library. Because nothing blocks, scalable systems are very reasonable to develop in Node.js.

If some of this language is unfamiliar, there is a full article on Blocking vs. Non-Blocking.

Node.js is similar in design to, and influenced by, systems like Ruby's Event Machine and Python's Twisted. Node.js takes the event model a bit further. It presents an event loop as a runtime construct instead of as a library. In other systems, there is always a blocking call to start the event-loop. Typically, behavior is defined through callbacks at the beginning of a script, and at the end a server is started through a blocking call like EventMachine::run(). In Node.js, there is no such start-the-event-loop call. Node.js simply enters the event loop after executing the input script. Node.js exits the event loop when there are no more callbacks to perform. This behavior is like browser JavaScript — the event loop is hidden from the user.

HTTP is a first-class citizen in Node.js, designed with streaming and low latency in mind. This makes Node.js well suited for the foundation of a web library or framework.

Node.js being designed without threads doesn't mean you can't take advantage of multiple cores in your environment. Child processes can be spawned by using our child_process.fork() API, and are designed to be easy to communicate with. Built upon that same interface is the cluster module, which allows you to share sockets between processes to enable load balancing over your cores.

Official Node.js Resources

To ensure authenticity and security when working with Node.js, always use official sources. Avoid trusting emails, binaries, or downloads from unofficial sources.

Official Node.js Domains

For downloading Node.js binaries and accessing official documentation, use only these domains:

nodejs.org
nodejs.dev (Redirects to https://nodejs.org)
iojs.org (Redirects to https://nodejs.org)

Official npm Packages

The Node.js team maintains the following official npm package scopes:

Additionally, the Node.js team maintains packages published by the nodejs-foundation npm account.

Using packages from the Node.js team guarantees that you are working with officially supported Node.js components.

Official GitHub Organizations

Node.js and related projects are maintained under these official GitHub organizations:

nodejs
pkgjs

Official Communication Channels

Node.js and the OpenJS Foundation communicate through various official and community-supported channels. You can find details on how to get involved on the Get Involved page.

Reporting Website Issues & Downtime

If you encounter issues with the Node.js website, report them at the Node.js website repository. For real-time updates on outages, visit the Node.js Status Page.