[von_lohengramm]

To be fair, so much of the C++ standard is literally just being explicit about what the standard does not define and often who defines it instead. But to be fair, it would probably be entirely reasonable to categorize that as essential language knowledge and a "part of the language."

Meanwhile, the ECMAScript spec really does not leave very much wiggle room. It (like every other web standard) is almost just documentation or often even pseudocode-ification of an actual implementation... Certainly makes you think.