[Daiz]

I'd say there are ways to combine both approaches - develop userscripts. While you can do tricks to use other libraries, simpler userscript development is easiest with just vanilla JS. It's how I got into JS myself - I first fixed up an userscript I was using that no longer worked, and then I used that userscript as a base to start building a more complex thing. Eventually I ended up completely rewriting the thing from scratch (and I did the same for the original userscript I fixed that started it all). I've been actually thinking of giving it another rewrite one of these days, this time opting to build the thing with Browserify...