after reading many tutorials about WASM I still figured out one of the most important questions for me:

Would I be able to call JS functions from WASM? or pass callbacks to WASM. Because WASM sounds like it goes agains the async nature of JS and I have the feeling that is going to be very annoying to merge both worlds.

Also if I cannot call any JS func from WASM it means I cannot call WebGL or Audio so I dont know what would I need the performance if I cannot access the most performance demanding APIs.