o.f = o.f + x fields in place
"Append to strings in place for fields, concat chains and character codes" made `obj.f += s` linear by handing the field's reference to a local before the concat. Two neighbouring forms still copied the whole string on every append, so their loops stayed quadratic: - `parts[i] += s` on a `string[]`: the old element reached the concat through a retained snapshot (the hidden %compoundOld local) while the slot still held it. 1.6M appends spread over four slots took 11 s. - `o.f = o.f + s` written out: the field read retains a snapshot and the field keeps its reference until the store. A statement `a[i] += rhs` on a `string[]` now lowers to `a[i] = (hole ? "undefined" : a[i]) + rhs` with the array and index saved first (evaluation order unchanged). The backend recognizes that store and the direct `recv.f = recv.f + suffix` on a plain string class or record field. After the snapshot and suffix are evaluated and the store guard ran, a field unlinks and releases its current value; an array slot in the hole-free prefix that still holds the snapshot is swapped for the immortal empty string and released. The concat then appends in place when nothing else holds the string, and the result is stored as before. Both paths unlink only when the snapshot is frame-owned (or immortal). Aliases, interned literals, throwing suffixes, suffixes that read or replace the field or element, rebound receivers and indices, holes, appends past the end and appends that grow the array keep their semantics (tests/corpus/string-field-append.ts, which also pins the field `+=` forms).
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.