[KonkeyDong69]

In addition to what the other replies said, feel free to eyeball the code required to embed SpiderMonkey in Firefox at https://github.com/mozilla/gecko-dev/tree/master/dom/binding.... It's rather large and complex.

[padenot]

This is not at all the code to embed SpiderMonkey in Firefox, those are the bindings from DOM APIs to the implementation of those APIs in Firefox. Above that, calling into this layer, is another layer that transforms JS calls into C++ calls (roughly).

The interface between SpiderMonkey and the rest of Firefox is here: https://searchfox.org/mozilla-central/source/js/src/jsapi.h.