Why HTML tutorial files contain js files

Question

Why HTML tutorial files contain js files

Answer 1

can you please elaborate what you want to ask....

Answer 2

I (sort of) agree that the lines between HTML, CSS and JavaScript could be cleaner, but some specific examples of the ones you'd like to discuss further for actual context would be nice.

Answer 3

In all appropriate uses of JavaScript, the purpose of the JavaScript is to enhance the way the web page works and to provide those of your visitors who have JavaScript enabled with a friendlier site than is possible without the JavaScript

Regards,
Will