Technical details

Node.js is a JavaScript runtime environment that processes incoming requests in a loop, called the event loop.

Internals[edit]

Node.js uses libuv under the hood to handle asynchronous events. Libuv is an abstraction layer for network and file system functionality on both Windows and POSIX-based systems such as Linux, macOS, OSS on NonStop, and Unix. Node.js relies on nghttp2 for HTTP support. As of version 20, Node.js uses the ada library which provides up-to-date WHATWG URL compliance. As of version 19.5, Node.js uses the simdutf library for fast Unicode validation and transcoding. As of version 21.3, Node.js uses the simdjson library for fast JSON parsing.