No, now it's web assembly[1], which is a flavour of assembly code that can run in all modern browsers because those browsers add WASM runtimes. It is as far away from JS as you can get while running in a browser. Even Flash and Java were closer to JS than WASM is.

You can implement a WASM runtime _in_ JavaScript (and people have done this, and it turned out to run so well that in some cases the performance hit was basically irrelevant), but that's because JS is Turing complete and any Turing complete system can emulate any other Turing complete system.

[1] https://webassembly.org/

No, that's still not JS. JS is a programming language. It doesn't mean "any program that runs in the browser".