I had to go back to working with React just recently.
I'm technically using TS, but the standard library is the same anyways. It hardly has everything imo.
It does have what it needs to interface with the browser, and quite a few -sometimes poorly thought out- facilities, but not much more.
Don't get me wrong, for a web scripting language it's plenty, but if one wants to use JS for stuff that isn't just putting a simple page on a screen, that's not enough.
Maybe you mean Node instead of JS?