Books! And ones that were obsolete almost as soon as they were put into print.
Technically I didn't learn before the internet era, but I started learning a long time ago when there weren't as many resources as there are today.
Funny observation: the times when I learn the most about JavaScript are the times when I am stuck on a problem and have zero internet or way to look it up, like on vacation, or on a flight, etc. Those are the most memorable times, so what you try that works or fails sticks with you :D