How do the Godot APIs get registered in JS?

Hi,

I've been toying around with the ECMAScript module for a bit and I've been experimenting with adding Clojurescript support via [shadow-cljs](https://github.com/arundilipan/CLJS-Godot). Basically, the status is that the outputted JS from Clojurescript works in Godot, but I'm having trouble getting a REPL working. I was wondering how/at what stage does the Godot API enter `globalThis`? Also, at what point can the Javascript code be run, can it only be run ingame or no?