Earlier quoted context omitted.
Since you're going to be pedantic, I will be too. Language is more than syntax. Language is the combination of Syntax and Meaning; its a system of communication. The word "Fooloofol" is syntactically correct English, but meaningless within the English language; and thus is not English. The english word "bark" is syntactically identical across more than one meaning; a dog barks next to the tree bark. Language isn't ju…
Node is a JavaScript runtime with some framework stuff on top. Not more, not less. The language is the implemented ECMAScript version. If you want to add a new (key)word to the language, there is a long commitment process. "Fooloofol" will give `Uncaught ReferenceError: fooloofool is not defined` in English and Node. :-D
But, ok: Node advertises itself as a Javascript runtime, but the standards body against which they are tracking makes it an ECMAScript runtime; not more, not less. Probably not more, I'll grant you; but certainly less! You can pick any formally standardized version of ECMAScript, and find that Node.js has incomplete support, in some cases even for years after publication [1]. Again; its close enough nowadays, especially outside of ESNext which really doesn't count, that we're not talking about a useful or meaningful difference; but rather a pedantic difference.
"Languages" formally specified independent of implementation are not languages. Language is the implementation; and the specification guides it. I'm not just talking about programming languages. I'm talking about spoken and written language as well.
For lack of a better specification; The Oxford English Dictionary is not English. The dictionary is both more and less than english. It has a very large center-of-the-venn-diagram. But: commonly spoken English words will always exist for which it doesn't yet have definition for (it's as of yet blissfully unaware of "bussin" and "rizz"). Simultaneously; it will have words that make no sense to modern speakers, or definitions that have fallen out of use.
It's the same situation with programming languages; the language is the implementation. The specification, if one exists, guides the implementation; but without absolutely no-more-no-less 100% coverage of the specification (which has not happened in NodeJS), and absolutely no-ambiguity-in-the-spec (which has never happened in any formal specification), they are meaningfully and inherently different. Because zero-ambiguity is impossible given fundamental constraints in politics, communication, and in a very real way physics: the specification isn't the language.
Here's an interesting fun fact: TypeScript; that programming language we all love. It has no formal specification. Yup! People have been asking Microsoft since 2016, when they last published the specification, to update it, but the team has (explicitly or not, I don't know) taken the stance that the implementation (and its test cases) are the specification. The language is the implementation.
So; what language is Deno-compatible code written in? The only accurate, formal, academic, correct answer is: Its written in Deno. The language is the implementation. Productively and usefully; its written in a language that is approximately similar enough to TypeScript that no one will notice.