[mijoharas]

We embedded spidermonkey as the JavaScript engine for the prime video application on games consoles and smart TVs when I was at Amazon (5 years ago+ not sure if they still use it). I've not embedded any other JS engines, but it wasn't too bad to embed.

[mijoharas]

Actually, I just realised what I said above was slightly inaccurate, we also built an application that embedded CEF, so I technically have embedded another js engine (that was 7+ years ago though, and my memory is spotty).

CEF was also relatively straightforward to use. Both times we were embedding them in C++ applications.