Boa 0.4.0

Boa is a Javascript lexer, parser and Just-in-Time compiler written in Rust. Currently, it has support for some of the language.


This is an experimental Javascript lexer, parser and compiler written in Rust. Currently, it has support for some of the language.
Build Status

This project is an attempted rewrite of Bebbington's Most of the Rust code has been rewritten from scratch.

Live Demo (WASM)

You can get more verbose errors when running from the command line


If you don't already have Rust installed rustup is the recommended tool to use. It will install Rust and allow you to switch between nightly, stable and beta. You can also install additional components.

curl -sSf | sh

Then simply clone this project and cargo build To develop on the web assembly side you can run yarn serve then go to http://localhost:8080


See Debugging

VSCode and Dockerfile

If you don't want to install everything on your machine, you can use the Dockerfile. Start VSCode in container mode (you may need the docker container plugin) and use the Dockerfile.

Web Assembly

This interpreter can be exposed to javascript! You can build the example locally with:

$ yarn install
$ yarn serve

In the console you can use window.evaluate to pass JavaScript in


See Project view


  • Checkout this project
  • Build cargo build
  • cargo run
  • You can make changes to tests/js/test.js and build again
  • If any JS doesn't work its a bug! Please raise an issue


Feel free to contact us on Discord




This project is licensed under the Unlicense or MIT licenses, at your option.