humble opinion: N years of using any language won't make you an expert. There's knowledge about how to express certain patterns in a given language, more like

humble opinion: N years of using any language won't make you an expert. There's knowledge about how to express certain patterns in a given language, more like an application design expertise. There's knowledge and familiarity with the APIs. And then there's the deep language knowledge, the one that pretty much only someone implementing a language VM, parser, compiler and other tools may acquire with time. Also, there are a lot of specifics about every particular JS implementation. Also, Dunning–Kruger :-) On the internals of VMs, https://mrale.ph/ https://mrale.ph/ has a lot of blog posts on internals/optimizations on V8. https://www.wingolog.org/tags/javascript https://www.wingolog.org/tags/javascript also has deep JS articles very freqently.