Can't speak to the size issue as I don't use emscripten, but I agree that most WASM output is waaay too large. Regarding JS, you need a small amount of JS to bootstrap your WASM program. In the browser, JS is the host environment and WASM is the guest. The host instantiates the WASM module and passes in capabilities that map to the module's declared imports.

https://developer.mozilla.org/en-US/docs/WebAssembly/Using_t...