Official documentation
Where to read more: MDN for the language, the Node.js 22 docs for fs, process and other built-in modules.
Runs in Zerethon IDE · Node.js 22
Official JavaScript documentation ↗
JavaScript the language is documented by MDN Web Docs; what Node.js adds (files, processes, streams, require) is in the Node.js API docs. The ECMAScript specification is the exact definition of the language.