I'm not sure what's the "correct" spec for the current C++ standard is. Still a big difference between these languages, but 846 pages isn't exactly small either.
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.
The ECMAScript language spec is closer to the C spec than the C++ spec, by a large margin. I'm not sure how much you can deduce about relative complexity from these figures.
I agree JS spec is like C, whereas some JS frameworks like Typescript are more like C++ where it's 100% using JS but w/ brevity to the end user. Think:
Note: I'm a moderate JS dev so correct me if I'm wrong.
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.