Chris Tate
5d8804db38
`for (let i = 0; i < s.length; i++) if (s.charCodeAt(i) === 32) n++` over a text with any non-ASCII character failed the loop version's ASCII guard and ran the checked loop. Each read tested the ASCII bit, compared the string with the runtime's published scan receiver, tested the bounds, loaded the units pointer, and kept the opaque fallback. The guard now also accepts a version's one string receiver when it is not ASCII. One runtime read publishes the string as the scan receiver (ScrStrScan), whose UTF-16 units the runtime holds once a scan has read it enough. The guard then tests the accesses against the published unit count, and a third copy of the loop reads each unit with one 16-bit load from the units pointer taken in the guard. The guard takes that path only while the runtime publishes the receiver itself, so the length it took is the receiver's UTF-16 length on both fast paths. Both fast copies read it for the receiver's `length`, which a while loop's condition otherwise asks the runtime for on every iteration. The runtime drops a string's units when the string is released or appended to in place, or when its index entry is evicted because another non-ASCII string is indexed. The receiver is a binding the loop does not write, so the first two cannot happen while the loop runs. A units copy is emitted only for a loop that uses unit-safe operations (string-unit-versions.ts): numbers, locals, records and class fields, typed arrays, number arrays, Math, the receiver's charCodeAt and length, and calls of functions made of the same operations that read no string. Tests of `s.charAt(i)` against one-unit literals now become charCodeAt compares in the IR pass (char-unit-locals.ts), so a version sees one kind of read.
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.