jco

JavaScript tooling for WebAssembly Components

A Bytecode Alliance project

Contributing | Chat on Zulip

Overview

Jco (jco) provides a Javascript-native toolchain for working with WebAssembly Components.

Jco aims to be a convenient multi-tool for the JS WebAssembly ecosystem.

With Jco (and related projects in this repository), you can:

• Build WebAssembly components from Javascript/Typescript with the help of componentize-js
• "Transpile" WebAssembly components into ES modules that can run in environments like NodeJS and the browser, combining platform-native WebAssembly core support with the advanced features of WebAssembly Components
• Run WebAssembly components whether single-shot applications or web servers (similar to wasmtime run/wasmtime serve)
• Reuse WebAssembly component workflows (e.g. building components, tranpsiling, etc) from your own JS projects
• Utilize wasm-tools as a library from JS

Organization

As Jco aims to do many things, it contains many subprojects that are organized in this repository:

Subproject	Language	Directory	Description
jco	Javascript	packages/jco	The jco CLI
preview2-shim	Javascript	packages/preview2-shim	Library that provides a mapping of WASI Preview2 for NodeJS and Browsers
js-component-bindgen	Rust	crates/js-component-bindgen	Enables jco transpile and other features, reusing the Rust WebAssembly ecosystem
js-component-bindgen-component	Rust	crates/js-component-bindgen-component	WebAssembly component that (when transipled) makes js-component-bindgen available in JS jco
wasm-tools-component	Rust	crates/wasm-tools-component	WebAssembly component containing pieces of wasm-tools used by jco

Quickstart

Jco can be used as either a library import or as a CLI via the jco command.

To install it, use npm (or your favorite npm equivalent):

npm install @bytecodealliance/jco

Note

If you're using jco to build components, you should also install componentize-js, which is dynamically imported:

npm install @bytecodealliance/componentize-js

Building an example component

For instructions on how to build an example component, see the Component model section on Javascript.

To see examples of common patterns, check out the example components folder (examples/components).

Learn more

For a deeper guide on the intricacies of Jco, read the Jco Book.

License

This project is licensed under the Apache 2.0 license with the LLVM exception. See LICENSE for more details.

Contributing

See the Contributing chapter of the Jco book.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.