Malte UblandClaude Opus 5.5 b234e06f20 Enforce the ECMAScript early errors the checker does not model
Static semantics reject a program before it runs. Until now the compiler
borrowed that rejection from whatever tsc happened to report, and Test262's
negative-parse suites show where the borrowing stops: programs the spec
makes SyntaxErrors compile and run. This adds the two largest families the
grab-bag misses (plan §7.7 D-4, option c), each under its own preflight
code, so a checker relaxation can never remove the only rejection a
parse-negative program had:

  SC0005  a statement list declares one lexical name twice
          (`{ class f {} async function f() {} }`)
  SC0006  a lexical name is `var`-declared in the same statement list
          (`switch (1) { case 1: let x; case 2: var x; }`)
  SC0007  a declaration where the grammar admits only a Statement
          (`while (false) function f() {}`, `l: class c {}`,
          `if (x) async function f() {}`)

frontend/early-errors.ts is a preflight walk over JavaScript sources, so a
rejected program fails where a tsc parse error fails, before any lowering.
A case block is one lexical scope across its clauses; a list's
VarDeclaredNames reach into nested blocks but never into a function or a
class body; and Annex B's allowances are honored exactly: two plain
function declarations may repeat in a sloppy block (B.3.3.1), and a plain
function may be an if/else body or a labelled statement in sloppy code
(B.3.2) — an async function, a generator or a class never gets either
allowance, and neither does any function as a loop or 'with' body.

Strictness comes from Node's own module classification (isNodeEsmFile7),
not from the checker's external-module bit: moduleDetection=force gives
every file module scope, CommonJS included, and taking that bit as
strictness cost the Annex B exemption on the annexB
function-redeclaration tests. Typed sources are untouched — their checker
diagnostics (TS2451 and friends) remain the gate, and re-reporting a
collision under a second code would only duplicate them.

tests/test262/support.mjs counts one of these codes at a location inside
the test's own source as the parse-negative match, the same standard the
helper already applies to tsc's early errors. The diagnostics fixtures pin
both families, including the strict half of SC0007 where Node refuses the
two Annex B shapes as well.

The pass only reads the AST and only refuses programs, so no typed
program's IR changes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-29 05:34:47 -07:00
2026-10-27 23:21:09 -05:00
2026-10-16 10:33:14 -05:00
2026-10-27 23:21:09 -05:00
2026-10-14 17:27:02 -05:00
2026-10-25 11:26:13 -05:00
2026-07-22 18:08:04 -05:00
2026-10-27 16:45:14 -05:00
2026-10-25 21:21:26 -05:00
2026-07-22 18:08:04 -05:00

scriptc

Vercel Labs Experiment npm version: scriptc License: Apache-2.0 npm downloads per month: 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

Contributing

See CONTRIBUTING.md for source setup, testing, native artifact builds, and docs development.

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