However, it would be a mistake to continue your education. I usually just use w3schools as a quick reference. In what way do you believe that it is “not working”?
The code is valid and when i copy it into a local file i see the expected results. They do have some comprehensive stuff but it is not enough but hey, i use it as additional resource besides mdn. For many beginners, w3schools has structured tutorials and playgrounds that offer a decent learning experience.
The certificates on w3schools, however, are just random certificates on a random internet site—i.e., they’re basically worthless and not worth paying money for. Covering popular subjects like html, css,.