Boa 0.5.0

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

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 inside the directory.



Either the Rust (RLS) or the Rust Analyzer extension is preferred. RLS is easier to set up but most of the development is moving towards Rust Analyzer.
Both of these plugins will help you with your Rust Development


There are some pre-defined tasks in tasks.json

  • Build - shift+cmd/ctrl+b should build and run cargo. You should be able to make changes and run this task.
  • Test - (there is no shortcut, you'll need to make one) - Runs Cargo Test.
    I personally set a shortcut of shift+cmd+option+T (or shift+ctrl+alt+T)

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.


See Debugging

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 To develop on the web assembly side you can run yarn serve then go to http://localhost:8080


See Milestones




  • Check out 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 then it's 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.