Is there any course like combining them here in codecademy?
Not yet! But who knows, maybe you could be the one to build it!!!
In the early days, there was a course that pulled them all together but for some reason it was not incorporated into the core tracks. The absence of a course does not preclude our using the resources at hand, though. We have the sandbox in the jQuery track, as well as other places.
The real fun comes when we attempt to translate jQuery back to the vanilla JS that is still running in abstract. Open the uncompressed jQuery script in an editor. (I haven't done this in years, but play along, thanks.)
$('.content :first-child').text() document.getElementsByClassName('content').textContent
as an example. It really is a great exercise to translate jQuery back to vanilla, just as a daily/weekly puzzle. Over time we strengthen our understanding of the language and the library. With this in one's kit moving forward into realms that frown upon or brush aside jQuery, you at least stand a chance of knowing what you are hearing and can give an appropriate response, or a knowing nod. You will find it is not everyone's cup of tea.
Needless to say, once we master the use of a library in conjunction with vanilla JS, we can branch on to other libraries and explore their own special possibilities, all leading up to frameworks and model views, which I bow out of discussing at this point, being a newb in this area.
The OP has the right idea... Apply everything at once on the proviso of doing it in order: HTML valid, CSS valid, JS behavior laid on last.
Once your behaviors are introduced, the only way to validate them is to inspect the source and copy that, then paste it into the validator. The only reason for failing HTML5 validation is a justified failure. In other words, you knew you would fail for that reason but have other reasons to justify why you let it fail.