mjs VS engine262

I implemented a GC in C++ a couple of years ago for a JS interpreter (some notes). Some of the optimization I spent a lot of effort on (NaN-tagging) might not be appropriate for your use case though, and I won't recommend using the exact same approach as I did.

I made a toy ECMAScript interpreter a couple of years ago: https://github.com/mras0/mjs

Not really notable, expect perhaps being the only one on the list with an ES1 mode? :) (Can't promise it's accurate though, as it was hard to find examples).

Otherwise pretty boring (C++, hand-written parser, AST interpreter, ES1/ES3/ES5.1 support minus some regexp/timezone/locale stuff).

engine262

Indeed. ECMA-262 has been implemented using JavaScript https://github.com/engine262/engine262.

Node.js is not the only JavaScript runtime. JavaScript runtimes have been written using JavaScript alone, see engine262. There is also Deno, QuickJS, txiki.js, Bun, none of which use COmmonJS by default, SpiderMonkey, et al.

for an interpreted language like JS, this project is really nice https://github.com/engine262/engine262. More or less 2 parts: parser and evaluator

That is a bit complex, so here's a list of JS engines: if you pick one written *in* JS, that would probably be most useful -- engine262 for example

then you might be impressed by https://github.com/engine262/engine262 as well

Engine 262

It's outside of what you asked for, but here's a JavaScript engine in JavaScript. Might make for some interesting bedtime reading!

Interesting to see a JS implementation written in JS:

https://github.com/engine262/engine262/

(The readme explains what the point of it is.)