Malte UblandClaude Opus 5.5 48d524a321 Lower a JavaScript read of an undeclared name to Node's ReferenceError
D-2: Node resolves a name nothing declares at run time, and the read always
throws the catchable `ReferenceError: x is not defined` at the access. A
`.js` read of such a name now compiles to exactly that throw instead of
refusing the program, with Node's message and Node's catchability.

The read's value is checked-dynamic (the checker's error-any after the
relaxation in the previous commit, narrowed by the use site where one
provides context), and every path through it unwinds before a use observes
the value, so the dynamic slot never carries a wrong value. Shorthand
position (`{ x }`) needs its own declaration test: there the checker
answers the PROPERTY symbol, so the name is bound when
`getShorthandAssignmentValueSymbol` has no value for it.

`typeof` is the one operator that never touches its operand value, and Node
answers "undefined" for an undeclared name, so `lowerDynTypeofTest` folds
the test to a literal before the read is ever lowered — `typeof x ===
"undefined"` stays true and `typeof x` alone prints "undefined".

No name that Node serves from the global object reaches this branch: the
compiler models those as declared (that is how the corpus reads `process`,
`console` and friends), so this is the name Node itself would report
missing.

The corpus program pins every shape: bare read, call, member read,
arithmetic, comparison, shorthand, destructuring default, typeof test, a
guarded read that keeps running after the throw, and a declared control.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-29 05:34:48 -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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Description
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Readme Apache-2.0
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C 21.9%
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