A union of exactly one emitted class or record arm and one unit arm (`C | undefined`, `C | null`) now lowers to the arm pointer itself: NULL is the unit arm and no `%ScrUnion` box is allocated. The decision lives in one registry (nullable-unions.ts) computed from the module, so in-memory and serialized-IR emission agree. Unions the runtime inspects as boxes (Map keys, Set elements) keep the tagged representation. Every structural read goes through representation-aware primitives (union-repr.ts, unionTag/unionPeek/unionNewOwned/unitInstanceRef taking the union id), and RC/trace dispatch resolves a nullable union to its arm's NULL-tolerant entry points, so containers, captures, fields, params, returns and promise payloads hold the plain pointer. Optional record fields use a module-scope immortal sentinel for the ABSENT state. Generic helper generators (JSON and join walkers, dyn conversions and checked casts, live stream refs, race/generator adapters, map get widening) handle both representations; fixed library unions assert they stay boxed. The stack-box analyses run over the boxed union table only. On main, the checked-extraction receivers of #781 (checked-narrows.ts) read the tag and payload through the same representation-aware primitives, and the stack-box and optional-array-read paths of #767 run over the boxed union table.
scriptc
scriptc compiles TypeScript and JavaScript to native executables and WebAssembly. It uses TypeScript's type information to compile supported code to native instructions. Static builds run without Node.js or a JavaScript engine.
For npm dependencies and any-typed code, enable --dynamic to include the embedded quickjs-ng engine. Dependency JavaScript is included at build time.
scriptc is experimental and supports a subset of JavaScript, TypeScript, and Node.js APIs. See the limitations and Node.js compatibility reference before using it for an existing project.
Installation
Install with Node.js 24 or later and npm:
$ npm install -g scriptc
The installed compiler runs natively on supported macOS, Linux, and Windows hosts. Native compilation and execution do not require Node.js. Standalone compiler archives are also available from GitHub Releases.
Executable builds require a platform linker and SDK/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}`);
Compile and run it in one step:
$ scriptc run hello.ts
hello, world
Or write a standalone executable:
$ scriptc build hello.ts -o hello
$ ./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 which operations compile statically, require dynamic execution, or are unsupported. 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
$ ./server
listening on http://localhost:8080
Use npm packages
Pass --dynamic to embed an npm package's JavaScript in the executable. The result does not 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 --dynamic -o cli
$ ./cli
hello from scriptc
Enabling --dynamic does not add support for unsupported statically typed calls. See npm dependencies for package resolution and the boundary between static and dynamic code.
Documentation
- Quickstart: installation and your first executable.
- 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.