wtf is plugin-exercises?

This is a plugin for GitBook, a tool for creating online books, that lets you add interactive coding exercises directly into your book's pages. Instead of just reading about programming concepts, readers get a built-in code editor where they can type solutions to challenges and find out immediately whether their answer is correct. Each exercise has four parts. The author writes a message explaining the task, some starter code that appears in the editor for the reader to build on, a reference solution, and validation code that checks whether the reader's answer is right. There's also an optional fifth part called context, which runs behind the scenes and can set up variables or functions the reader's code needs to work with. When a reader submits their code, the validation logic runs against it and tells them if they solved it correctly. This would be useful for anyone writing a programming tutorial or course. For example, if you're writing a book teaching JavaScript basics, you could include an exercise asking the reader to create a variable equal to 10. They type their answer into the editor, and the plugin checks it on the spot rather than making them switch to a separate coding environment. The exercises currently support JavaScript only. The README doesn't go into detail about the GitBook platform itself, but the core idea is straightforward: turn a passive reading experience into a hands-on one where people practice what they learn as they go.