First touch of fresh memory costs the allocating thread a page fault and a page clear. Linux executables now hand that to a helper thread: - Size-class slices raise their bump limits in steps (256 KiB on the small-page prefix, half a huge page after the switch), and each step asks the helper to fault in the next step ahead with MADV_POPULATE_WRITE, which commits zeroed pages without storing, so it cannot race with carving. A slice holds at most about one step of untouched committed memory; a slice's first chunk is not faulted ahead. - glibc's heap gets a 16 MiB top pad and the helper faults in each brk extension as soon as it sees the break move (checked after every request, then polled every 1 ms while it keeps growing; an idle program does not wake it). The fast paths are unchanged; pages the helper has not reached are still faulted by the owner. The helper masks all signals. SCR_SA_PREFAULT=0 turns it off, SCR_SA_PREFAULT_HEAP=0 keeps glibc's heap defaults; kernels without MADV_POPULATE_WRITE (< 5.14) fall back to the old policy, and library archives keep it. The slice-growth allocator check now carves past several huge-page steps and checks every fresh block reads as zero (UBSan and TSan builds run with the helper).
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.