I actually think there's a third way of "using JS to write Wasm", which is to have a JS library which has instructions to emit "hand-written" Wasm bytecode. Example of such a library: https://github.com/iden3/wasmbuilder

That's actually what I was thinking about when picking this option! Think of the following situation:

- You're a JS developer, and want to write a client / library mainly with JS

- You want to use Wasm only for some narrow, performance-critical parts

In this case, you may not want to use something like Rust, because that adds tooling overhead, makes the Wasm bytecode bigger & makes it harder to hand-optimize the Wasm. On the other hand, you might not want to directly write the Wasm in raw WAT, because that has crappy DX.

In this situation, having a JS library is a viable way to make the writing of raw Wasm somewhat more efficient. Example of this pattern being used in the wild: https://github.com/iden3/wasmcurves/blob/master/src/bls12381...