Javy: A Jav aScript to WebAssembl y toolchain

About this repo

Introduction: Run your JavaScript on WebAssembly. Javy takes your JavaScript code, and executes it in a WebAssebmly embedded JavaScript runtime.

Javy is currently used for the beta Shopify Scripts platform. We intend on supporting and improving this runtime in that context. Eventually this project should be a good general purpose JavaScript runtime but that is not the current goal.

Contributing

Javy is a beta project and will be under major development. We welcome feedback, bug reports and bug fixes. We're also happy to discuss feature development but please discuss the features in an issue before contributing. All contributors will be prompted to sign our CLA.

Build

• Rust v1.53.0
• rustup
• wasm32-wasi, can be installed via rustup target add wasm32-wasi
• cmake, depending on your operating system and architecture, it might not be installed by default. On Mac it can be installed with homebrew via brew install cmake
• Rosetta 2 if running MacOS on Apple Silicon, can be installed via softwareupdate --install-rosetta
• Install the wasi-sdk by running make download-wasi-sdk

Development

• wasmtime-cli, can be installed via cargo install wasmtime-cli (required for cargo-wasi)
• cargo-wasi, can be installed via cargo install cargo-wasi

Building

After all the dependencies are installed, run make. You should now have access to the executable in target/release/javy

Alternatively you can run make && cargo install --path crates/cli. After running the previous command you'll have a global installation of the executable.

Compiling to WebAssembly

You can create a WebAssembly binary from JavaScript by:

javy index.js -o destination/index.wasm

For more information on the commands you can run javy --help

Releasing

1. Create a tag for the new version like v0.2.0

git tag v0.2.0
git push origin --tags

2. Create a new release from the new tag in github here.
3. A GitHub Action will trigger for publish.yml when a release is published (i.e. it doesn't run on drafts), creating the artifacts for downloading. However this does not currently support arm-macos, ie. M1 Macs.
4. Manually build this on a m1 mac

gzip -k -f target/release/javy && mv target/release/javy.gz javy-arm-macos-v0.2.0.gz

5. Manually create the shasum file

shasum -a 256 javy-arm-macos-v0.2.0.gz | awk '{ print $1 }' > javy-arm-macos-v0.2.0.gz.sha256

6. Attach both files to the new release page