useCommonJs() is marked as an unresolved reference...

# javascript

[Grantas33]

useCommonJs() is marked as an unresolved reference when I try to use it to compile js in kotlin multiplatform 1.4-M1.

js {
    useCommonJs()
    produceExecutable()
    browser {}
}

Is there a way to compile typescript declarations in commonJs format in kotlin multiplatform 1.4-M1?

[Derek Ellis]

You can still manually set it to output commonjs. Not sure why the helper function doesn't work in 1.4-M1

[Justin]

How do you manually set it?

[Derek Ellis]

target {
        browser {
            webpackTask {
                output.libraryTarget = COMMONJS 
                //output.libraryTarget = "commonjs" // alternative
             }
        }
    }

[Derek Ellis]

This was from here https://kotlinlang.org/docs/reference/js-modules.html, so if you're in a multiplatform project you'd have js instead of target

[Justin]

Thanks! Is it the same if I’m using nodejs()? This is the config I currently have in `build.gradle.kts`:

kotlin {
    {...}

    js("js") {
        nodejs()

        compilations["main"].defaultSourceSet.dependencies {
            implementation(kotlin("stdlib-js", kotlin_version))
        }
    }
}

[Derek Ellis]

It doesn't seem like nodejs has a webpackTask thing, but this will also work and apply it to all js targets (it's what useCommonJs does under the hood).

compilations.all {
   it.compileKotlinTask.kotlinOptions {
       moduleKind = "commonjs"
       sourceMap = true
       sourceMapEmbedSources = null
   }
}

[Justin]

Thanks Derek. Now I have a new error that suggests maybe I’m on the right track at least?

> Task :compileProductionKotlinJs FAILED
e: java.lang.AssertionError: Properties without fields are not supported com.project.models.Flow.Companion_instance

This is `Flow`:

@Serializable
@CommonJsExport
data class Flow(
    val id: String, 
    val variables: Variables,           
    val locales: Locales,               
    val data: FlowData
)

[Justin]

Best guess is that the serializable annotation is autogen’ing a companion object that doesn’t play nice with typescript def generation?

[Derek Ellis]

If you create a property without a backing field in some other class, does it complain about that too? I'm not really sure what the limitations of the IR backend/TypeScript definition generation are

[Justin]

It looks like there’s an issue already created about this conflict with @Serialization. I was really hoping to use this for a work project which needs to be delivered relatively soon. Hopefully there’s either a workaround or a fix for this in time.

[Justin]

See more here:

https://kotlinlang.slack.com/archives/C0B8L3U69/p1589983826229100