Answer to: Are there any functional approaches, to have variables that feel global (no need to pass them around explicitly), yet are local to an instance?

JavaScript functions call() and bind() support passing the context object when calling functions/methods. The JavaScript call() & apply() vs bind()? Stack Overflow thread lists details about each function. Use .bind() when you want that function to later be called with a certain context, useful in events. Use .call() or .apply() when you want to invoke the function immediately, and modify the context.