js2wasm Native Messaging host

Install

js2wasm

Direct AOT compilation from JavaScript and TypeScript to WebAssembly GC.

bun install --trust https://github.com/loopdive/js2

Hosts

• nm_js2wasm_wasi_p1.ts

Raw WASI Preview 1 syscalls over linear memory | wasi_snapshot_preview1 (fd_read/fd_write) + wasm:memory (intrinsic, lowers inline) | sync blocking fd_read/fd_write loop | only wasi_snapshot_preview1 | wasmtime / wasmer / wazero| standalone WASI P1 command module (owns + exports its own memory)

• nm_js2wasm_node_fs.ts

Node synchronous node:fs fd IO | node:fs (readSync/writeSync) | sync readSync/writeSync read-until loop | only wasi_snapshot_preview1 (inlined); or a node:fs interface with --link node:fs | wasmtime and unmodified under real node | standalone WASI P1 command module (or a node:fs-linkable module)

• nm_js2wasam_node_process.ts

Node async streaming stdio | process.stdin (global) Readable + process.stdout.write | async event-driven 'data'/'end', incremental framing | only wasi_snapshot_preview1 | wasmtime (drives the injected fd0 reactor / event loop) | standalone WASI P1 command module with an event loop

• nm_js2wasm_deno.ts

Deno stdio surface (Deno.stdin/Deno.stdout) | (lands separately) | sync (readSync/writeSync) | (WASI-targeted; filled in when it lands)| Deno / a WASI runtime | standalone WASI module

See Five hosts, one wire protocol — a comparison.

Transpile TypeScript to JavaScript, compile JavaScript to WASM GC

bun build ./node_modules/@loopdive/js2/examples/native-messaging/nm_js2wasm_wasi_p1.ts --no-bundle --outfile=nm_js2wasm_wasi_p1.js

bun ./node_modules/@loopdive/js2/src/cli.ts nm_js2wasm_wasi_p1.js --wit --target wasi -o .

Compile all hosts

bun compile_hosts.js

Bundle js2wasm to single script

bun build ./node_modules/@loopdive/js2/src/cli.ts --target=node --minify --outfile=js2wasm.js 

Installation and usage on Chrome and Chromium

1. Navigate to chrome://extensions.
2. Toggle Developer mode.
3. Click Load unpacked.
4. Select native-messaging-js2wasm folder.
5. Note the generated extension ID.
6. Open nm_js2wasm.json in a text editor, set "path" to absolute path of nm_js2wasm.sh (executes your local wasmtime or other WebAssembly runtime and the compiled nm_js2wasm_wasi_p1.wasm or nm_js2wasm_<node|fs|node_process|deno>.wasm file), and chrome-extension://<ID>/ using ID from 5 in "allowed_origins" array; and make sure wasmtime is in PATH and nm_js2wasm.sh is executable.
7. Copy the nm_js2wasm.json file to Chrome or Chromium configuration folder, e.g., Chromium on Linux ~/.config/chromium/NativeMessagingHosts; Chrome dev channel on Linux ~/.config/google-chrome-unstable/NativeMessagingHosts.
8. To test click service worker link in panel of unpacked extension which is DevTools for background.js in MV3 ServiceWorker, observe echo'ed message from js2wasm Native Messaging host. To disconnect run port.disconnect().

The Native Messaging host echoes back the message passed.

For differences between OS and browser implementations see Chrome incompatibilities.

License

Do What the Fuck You Want to Public License WTFPLv2