There are two main components to scratch-js:

scratch-js is a library which makes it easy to create games in Javascript. The library handles rendering sprites, collision detection, audio, and more. It is designed to be easy-to-use for real human beings. If you're a person, you can make games with scratch-js.

But scratch-js also has a second trick up its sleeve...

The design of the scratch-js library closely mimics that of the Scratch programming language. This is no accident; it allows for direct, easy translation from Scratch to JavaScript. There are a lot of reasons why this is difficult without the library (mostly the way that Scratch handles asynchronous code), but with scratch-js alongside, the translation is stupid simple.

All of this means that a compiler can exist which translates Scratch projects directly into usable Javascript. This isn't ugly compilation that leaves little room for human input. The final code is clear and concise, exactly the same as the Scratch project from which it is created.

> git clone https://github.com/PullJosh/scratch-js.git
> cd scratch-js

(Note that the cd command takes us into the repo directory, NOT the scratch-js folder within it!)

Everything in this repo can be opened in a browser directly. Unfortunately for us, javascript modules must come from a server like localhost rather than straight from the file system, so we need to serve the repo's files on localhost.

There are plenty of different ways to do this. If you have node installed, you can use http-server:

> npx http-server -p 3000

Once you start the server, open http:https://localhost:3000/example-project/index.html to see the example project in action!