What is nstdlib?

nstdlib is a small, runtime-agnostic version of the Node.js standard library. It packages modules such as path, stream, url, and assert as plain ES modules for browsers, workers, bundlers, and other JavaScript runtimes. It is built from Node.js's own source rather than reimplemented, so you can use familiar imports such as import path from "nstdlib/path" without running Node.js itself.

#Who it's for

• Bundlers - nstdlib/* subpaths are ordinary ES modules a bundler can import, alias node:* specifiers to, and tree-shake like any package.
• Workers and other constrained runtimes - Cloudflare Workers, service workers, and similar places Node itself can't run, but you still want path.join, a real URL, or EventEmitter.
• Browsers - the pure-JavaScript half of the standard library runs in a browser tab. The half that needs an operating system fails loudly instead of silently - see Usage.
• Other JavaScript runtimes - anything that is neither Node nor a browser.
• nstd, the standalone runtime binary built on top of nstdlib - it pairs nstdlib with a host written in Zig so it can run real Node programs with no Node installed. It's the proof that nstdlib works outside Node.

#Compatibility

A good part of the pure-JavaScript half of Node's standard library behaves like the real thing; the half that needs the operating system has more gaps. Within a single module some exports are fully verified against real Node, some only have the right shape and throw when you call them, and some are simply untested. The API pages list every module's actual, measured status.

#nstdlib vs. nstd

This page, and the rest of this section, are about the package: something you npm install and import from your own code. What is nstd? covers the other half of this project - a single executable, built from nstdlib, that runs Node programs with no Node installed at all. If you want a library to import, you're in the right place; if you want to run a .js file without installing Node, that's nstd.