Is there any way to use a map in a JsExport annota...

# javascript

[quiro]

Is there any way to use a map in a JsExport annotated class and have it be a simple javascript object? For example:

@JsExport data class Response(val b: Map<String, Int>)

@JsExport fun response() = Response(mutableMapOf("c", 1))

On the javascript side, I expect something similar to be returned, but instead what I see
{ "b": { "c": 1 } }

When I debug this on the javascript side, I see a lot of properties are

{
  "b": {
    "_keys_1": null,
    "_values_1": null,
    "keysView_1": null,
    "valuesView_1": null,
    "entriesView_1": null,
    ... // a lot more properties
  }
}

[jw]

This is coming in 2.x

[jw]

I can't find the announcement

[jw]

It was on the blog or somewhere. Still looking

[jw]

https://github.com/JetBrains/kotlin/tree/master/plugins/js-plain-objects

[quiro]

Thanks Jake, I'm not sure this works for a Map<String, V> , where the keys are not defined at compile time 🤔

[turansky]

@JsPlainObject - annotation for external interfaces.
You can use it right now in Kotlin 1.9 with jso factory method, which will create required JSO.

[turansky]

If fields are dynamic - you can use recordOf function.

[turansky]

external interface + jso or factory created by @JsPlainObject = JSO with strict fields
Record interface + recordOf factory = JSO with dynamic fields

[Edoardo Luppi]

Are you on 1.9, or 2.0?

[Edoardo Luppi]

Artem added the possibility of js-exporting collections to the JS side in 2.0.
However, the exposed map isn't a JS Map, or a JS dictionary.

JS side example:

const mutableMap = provideMutableMap() // Kotlin fun
const mutableMapView = mutableMap.asJsMapView() // Allow JS consumer to modify the Kotlin map