If I want a shared source set for

js

and

wasmJs

should I just use

wasmJs

and leave out

js

entirely?

It depends on the use case. If you have a reach @JsExport API (classes, properties, etc), in this case you still can't drop

js

target, but if you don't have exported declarations or the exported declarations are functions - yes, you can use only

wasmJs

wasmJs

is a Kotlin/Wasm target that creates Wasm, which is expected to run in a JS environment.

js

is a Kotlin/JS target that produces JS. You need both if you want to support both JS and Wasm platforms.

So if my library only supports

wasmJs

and a Kotlin/JS consumer wanted to use it, it wouldn't be able to? i.e. it can't import it and wrap it or something like that?

To a large extent yes. Although it is possible, you would need to go through regular JS interop. Your library would need to export functions from Wasm to JS. And Kotlin/JS consumer would need to have

external

declarations describing your API.