How do I import and use an async JS function in Kotlin/JS?

Question

I'm having issues importing a Javascript async function into my Kotlin code.

Here is an example Javascript function :

export async function signUp(email, password){

    console.log("Signing Up");

    try {
        const userCred = await createUserWithEmailAndPassword(auth, email, password);
        console.log(userCred);

        return userCred.user.accessToken
    }
    catch (e) {
        console.log(e);
    }

}

I import it in my Kotlin as such :

@JsModule("@jlengrand/firebase-ports")
@JsNonModule
external object FirebasePorts{

    suspend fun signUp(email: String, password: String) : String
}

When using the function, I expect to get a String out of it :

    var user : String? by mutableStateOf(null)

            Button( attrs = {
                onClick { 
                    GlobalScope.launch {
                        user = FirebasePorts.signUp(email, password)
                    }
                }
            }) {
                Text("Login!")
            }

            // printing the value
            TextArea(value = user.toString())

However, what I get instead is a Promise

What am I doing wrong?

Thanks!

Karel Petranek · Accepted Answer · 2022-03-31 14:13:16Z

3

Async functions in JS are currently not mapped to suspend functions in Kotlin. To get an async function working in Kotlin, you need to deal with the native promises:

import kotlin.js.Promise

@JsModule("@jlengrand/firebase-ports")
@JsNonModule
external object FirebasePorts {

   fun signUp(email: String, password: String) : Promise<String>
}

Then use FirebasePorts.signUp(...).then { ... } to access the value.

edited Mar 31, 2022 at 14:13

answered Mar 30, 2022 at 14:34

Karel Petranek

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1 Comment

jlengrand Over a year ago

Yup, that works thanks! Expecting suspend to be mapped to async was clearly a stretch. Thank you!

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