Kotlin/JS external declaration - "Name contains illegal chars that can't appear in JavaScript identifier"

EDIT: This is not supported yet and tracked on Kotlin YouTrack

I'm trying to write a Kotlin external declaration matching the following Typescript interface (this is valid TS to represent JavaScript accesses via headers['content-length']):

export interface Headers {
  'content-length'?: string;
}

Dukat generates the following, which should be considered valid:

external interface Headers {
    var `content-length`: String? get() = definedExternally; set(value) = definedExternally
}

But now the compiler complains with:

Name contains illegal chars that can't appear in JavaScript identifier

It is true that it can't appear in a JS identifier, but it doesn't have to. All Kotlin accesses to this property like:

val length = headers.`content-length`

could be valid if compiled to const length = headers["content-length"].

I tried to use @JsName to work around it the following ways:

@JsName("content-length")
@JsName("'content-length'")
@JsName("\"content-length\"")

But all of these fail because they only allow strings that are valid JS identifiers. Is there a way to work around this?

Solution

I suggest working around this problem by defining an empty interface to stand in for such objects in Kotlin, plus an extension property to get and set the value:

external interface KHeader // stands in for JavaScript objects with content-length property

var KHeader.contentLength: String
   get() = this.asDynamic()["content-length"]
   set(value) { this.asDynamic()["content-length"] = value }

In this way you can use Header JavaScript objects in Kotlin with camel case (see playground):

fun main() {
    val jsObject = js("{}")
    jsObject["content-length"] = "44"
    val randomHeader = jsObject as KHeader
    println(randomHeader.contentLength) // prints 44
    randomHeader.contentLength = "55"
    println(randomHeader.contentLength)  // prints 55
}