[Leszek]

The complex parts of JavaScript are the semantics, not the syntax. You could reasonably easily spec a bytecode for JS to get rid of the syntax part, but nothing would change in the complexity (almost all modern engines parse to bytecode as the first step and operate on bytecode from then on).

If you wanted to implement JS in wasm, you'd either need a bunch of wasm extensions for JS semantics (dynamic object shape, prototypal inheritance, etc), or you'd need to implement them in wasm from scratch and basically ship a JS runtime written in wasm. Either that, or you need to change the language, which means de facto adding a new language since the old JS still has to stick around for old pages.

[notepad0x90]

I admit I don't have depth of knowledge with how JS and Wasm work behind the scenes, but you can already compile JS to wasm. Forgive the ignorance, but what am I missing here? When you compile JS to wasm, aren't the semantics and language behaviors already addressed?

My understanding was that things like DOM manipulation APIs would need to be (and are) exposed to the WASM runtime so that the JS-to-WASM compiler could do all the right bytecode "linking".

My idea is that if JS itself was require to in WASM, and native JS support didn't exist, the complexity in browsers would be reduced dramatically. And developers will be free to use different languages. Browsers will focus on APIs instead of language semantics. no more V8!

[Leszek]

You can't currently "compile JS to Wasm", you can compile a JS engine (likely written in C++) to Wasm and run JS inside that (almost certainly at lower speed). So instead of "no more V8", it's closer to "ship V8 as part of the website, instead of part of the browser". Exposing DOM APIs to Wasm is a completely different question, though even those would actually have to be new APIs with a new API design that works for Wasm, since the existing DOM APIs are effectively defined in terms of JS objects being passed around.