I think the sentiment of "you dont know what you dont know" is especially cumbersome with JS, since its usability is so much defined by its extensions (WebAPIs, runtimes etc.)

Reading into specs (ECMAScript[0], W3C[1]), some more approachable explanations[2] of them and some implementations[3, 4] of embedded engines seem to be my approach.

[0]: https://tc39.es/ecma262/2020/ [1]: https://github.com/w3c [2]: http://dmitrysoshnikov.com/ecmascript/javascript-the-core-2n... [3]: https://bellard.org/quickjs/ [4]: https://v8.dev/docs/embed