Node.js

Node.js, also called node, is a runtime environment for server-side applications, released in 2009. It is an open source software architecture that is event-driven: it detects and reacts to things that happen, as they happen.

Node provides an input/output API (application programming interface) that is non-blocking, meaning node programs can make I/O requests and continue without waiting for the response. This approach has important uses in web applications, where the user can use your site, page, or application even while I/O is occurring in the background. This type of application is called asynchronous because individual operations can proceed independently of the main program flow.

Node programs are written in JavaScript. Its JavaScript engine is V8, the open source engine which was developed at Google for its Chrome web browser.

Here is a simple web server, written for node.js, which listens on port 8080 for HTTP (hypertext transfer protocol) requests, and responds with "Hello, World!":

var http = require('http');
http.createServer(function (request, response) {
  response.writeHead(200, {'Content-Type': 'text/plain'});
  response.end('Hello, World!\n');
}).listen(8080);

Node was created by web developer Ryan Dahl, who was frustrated by the blocking nature of most web server software. Node is used to power websites for Dow Jones, New York Times, PayPal, eBay, and Uber, among other companies.

Applications, Asynchronous, Environment, Programming terms, Server, Tech stack, Web application