Chris Tate
fa98044a5c
Node runs the callback of an operation that a callback-style API starts
with the AsyncLocalStorage stores active when the call started it. The
runtime invokes these callbacks from the event loop, where the context is
empty, so getStore() answered undefined in fs, crypto, zlib, dns,
child_process, net, http and dgram callbacks.
In programs whose scheduling carries contexts (RuntimeFeatures
asyncContext), the lowering now binds each completion-callback argument to
the context active at the call (completion-callbacks.ts): typed closures
through als.bindCallback, whose bound closure enters through a thunk the
backend emits once per callback signature, and dyn functions through
als.bindCallbackDyn. The fs callback family binds in the runtime, where
scr_fs_cb_schedule queues the callback. Other programs compile as before.
AsyncLocalStorage.bind(fn) binds fn to the active context, also when it
is empty (a typed function keeps its type; in JavaScript files the bound
function is named "bound" and forwards its receiver, as in Node).
AsyncLocalStorage.snapshot() answers a function that runs its callback in
the snapshot's context. new AsyncLocalStorage({ defaultValue, name })
validates its options as Node does; getStore() answers the default value
where the store has no entry, exit() runs its callback with the store
undefined, and the name property answers the name option or "".
Event listeners on sockets, requests, responses and streams, stream
callbacks, server.close(callback) and https and tls callbacks still run
with no store; the limitations page lists them. Corpus 7110-7112.
scriptc
scriptc compiles TypeScript and JavaScript to native executables and WebAssembly. It uses the types checked by the TypeScript compiler to generate machine code, and the output runs without Node.js installed. npm packages your program imports compile along with it. Code scriptc can't compile is reported at build time with a diagnostic and, where available, a rewrite hint.
scriptc is experimental and supports a subset of JavaScript, TypeScript, and Node.js APIs. Run scriptc coverage on an existing program to see how much of it compiles, and see the limitations and Node.js compatibility reference for details.
Installation
Install with Node.js 24 or later and npm:
$ npm install -g scriptc
The installed compiler runs natively on macOS, Linux, and Windows. Node.js is needed only to install it and to run WASI modules with scriptc run. Standalone compiler archives are also available from GitHub Releases.
Building executables requires a linker and the platform SDK or sysroot. See the quickstart for prerequisites and platform support for host requirements, cross-compilation, and WebAssembly.
Build a program
Create hello.ts:
const who = process.argv.length > 2 ? process.argv[2] : "world";
console.log(`hello, ${who}`);
scriptc run compiles the file and runs the result:
$ scriptc run hello.ts
hello, world
scriptc build writes an executable:
$ scriptc build hello.ts -o hello >/dev/null
$ ./hello scriptc
hello, scriptc
These examples use POSIX shell syntax. On Windows, build hello.exe and run it with .\hello.exe.
Use scriptc coverage hello.ts to check what compiles before you build. See coverage reports for details.
Use Node APIs
Supported Node APIs compile to the native runtime. For example, server.ts:
import { createServer } from "node:http";
const server = createServer((req, res) => {
res.setHeader("content-type", "application/json");
res.end(JSON.stringify({ path: req.url }));
});
server.listen(8080, () => {
console.log("listening on http://localhost:8080");
});
$ scriptc build server.ts -o server >/dev/null
$ ./server
listening on http://localhost:8080
Use npm packages
npm packages compile into the executable with your code, so it doesn't read node_modules at runtime.
Create cli.ts:
import pc from "picocolors";
console.log(pc.green("hello from scriptc"));
$ npm install picocolors
$ scriptc build cli.ts -o cli >/dev/null
$ ./cli
hello from scriptc
Package support is partial. See npm dependencies for which packages compile and how to check them.
Documentation
- Introduction: what scriptc is and what you can build.
- Quickstart: installation and your first executable.
- Coverage reports: check whether an existing program compiles.
- Platform support: cross-compilation and WebAssembly.
- CLI reference: commands, options, and output formats.
- Native program objects: use compiler output in external builds.
- Native FFI: call C ABI functions from compiled programs.
- WebAssembly modules: build and embed WASI modules.
- Examples: programs and integration examples in this repository.
Contributing
See CONTRIBUTING.md for source setup, testing, native artifact builds, and docs development.