I'm an old radical assholes who you don't have to ever listen to but if you want to learn JavaScript, CSS, HTML learn the languages. Frameworks are limiting our greater abilities. Haven't we had enough of bad code it's 30 freaking years of the web now
I'm an old conservative asshole who you don't have to listen to, but if you want to learn JavaScript, CSS, HTML, etc start learning from the fundamentals of those languages.
Not the libraries, not the frameworks.
There is too much magic happening under the hood hidden from you.