I am working on upgrading our kotlin version from ...

# javascript

[Phil Kagebein]

I am working on upgrading our kotlin version from 2.1.20 -> 2.2.10. Previously, we used KtMap.getInstance().fromJsMap() to convert a JS Map to a Kotlin map so that the client can send some data back to KM. However, in 2.2.10 getInstance() is not available anymore. Is there a more preferred way to do these sorts of operators for objects like KtMap or KtList?

[Edoardo Luppi]

Are you compiling to CJS or ESM?

[Edoardo Luppi]

With ESM export, it appears the generated JS code correctly contains a KtMap.getInstance().
However the generated TS declarations are incorrect.

This might be https://youtrack.jetbrains.com/issue/KT-79926, @Artem Kobzar should be able to confirm.

[Artem Kobzar]

+1 to @Edoardo Luppi
There was a bug that inside the d.ts file dropped getInstance from the d.ts .
However, since the 2.3.0 for the KtMap and KtList the getInstance will be dropped and you could use just KtMap.fromJsMap from both ESM and CJS (we did it to eliminate differences between the module systems to make the migration smoother)

[Phil Kagebein]

I appreciate the detailed answers! Good to know that in 2.3.0 there will be a better solution! We are compiling to ESM, for now, I have added an annotation to ignore the TS error

[Seth Madison]

@Artem Kobzar can you confirm that the fix will also include object types that inherit from sealed interfaces? We have code like this:

@JsExport
sealed interface Foo

@JsExport
object Bar : Foo

And the codegen is suffering from a similar problem. We get:

export declare interface Foo {
    readonly __doNotUseOrImplementIt: {
        readonly "philo.Foo": unique symbol;
    };
}
export declare abstract class Bar {
    static readonly getInstance: () => typeof Bar.$metadata$.type;
    private constructor();
}
/** @deprecated $metadata$ is used for internal purposes, please don't use it in your code, because it can be removed at any moment */
export declare namespace Bar.$metadata$ {
    abstract class type extends KtSingleton<constructor>() {
        private constructor();
    }
    abstract class constructor implements Foo {
        readonly __doNotUseOrImplementIt: Foo["__doNotUseOrImplementIt"];
        private constructor();
    }
}

The problem is that getInstance() is returning the type, not the object itself, so TS complains.

[Artem Kobzar]

@Seth Madison yes, the issue should be solved. Right now it will be like this: https://www.typescriptlang.org/play/?#code/CYUwxgNghgTiAEAzArgOzAFwJYHtXwGkMBlLVAcwhAzwB4AV[…]UALoA0dC4Fg2xV3Mw2v15tNnwjEa6TtmWyiTjDhTPEcuS5qovpsEAA

[Seth Madison]

Realized I never responded here. The bug was mine. 😞

[Artem Kobzar]

@Seth Madison, and thank you so much for filling it out. As a result, we've found a better solution for exporting interfaces with Companion. 🙏

[Seth Madison]

Awesome!!