So I've got an externally defined interface with a...

# webassembly

[Matt Nelson]

So I've got an externally defined interface with a function on it. That function takes a callback function, but wasmJs keeps crying that I'm using Unit. Is there any way around this?

@JsName("EventEmitter")
internal external interface JsEventEmitter {
    fun on(
        event: String,
        listener: Function<Unit>,
    ): JsEventEmitter
}

Type 'Function<Unit>' cannot be used as value parameter type of JS interop function. Only external, primitive, string, and function types are supported in Kotlin/Wasm JS interop.

[Robert Jaros]

As far as I know you have to use () -> Unit instead

[Matt Nelson]

That worked, thanks!

@JsName("EventEmitter")
internal external interface JsEventEmitter {
    fun <T: JsAny?> on(
        event: String,
        listener: (T) -> Unit,
    ): JsEventEmitter
}

[turansky]

Is it Node.js EventEmitter ?

[Matt Nelson]

Yes

[Matt Nelson]

Boom. wasmJs support added to kmp-process

[turansky]

1. We plan to provide Node.js declarations for WasmJS in this issue
2. Kotlin/JS EventEmitter you can find here
3. Static on supports cancellation

[Matt Nelson]

Yep. I am aware. My libraries will never use those dependencies.

[turansky]

Is it common restriction for external dependencies?

[Matt Nelson]

Yes, I try to limit dependencies to only what is absolutely necessary. As it relates to Js/WasmJs, I only need a few external definitions, so.