如何从纯JavaScript数组创建kotlin.collections.Set？

Question

I'm trying to call from plain JavaScript into a Kotlin module that has been compiled into JavaScript. One of the Kotlin methods inside the module requires a kotlin.collections.Set to be passed. How can I create such a set object from a plain JavaScript array? I've looked into the compiled code, and Kotlin makes internal references to methods like Kotlin.kotlin.collections.setOf_i5x0yv$ but I see no way to call these from outside.

Answer 1

According to the Kotlin documentation Sets are not represented in Javascript.

Arrays on the other hand are mapped. Therefore a simple function can be written which maps a Javascript Array into a Kotlin Set.

@JsName("createSetFromJsArray")
fun <TValue> createSetFromJsArray(array: Array<TValue>) = array.toSet()

This function can be used when calling a Kotlin function from Javascript like this:

var test = ["a", "b", "c"];
aKotlinFunction(createSetFromJsArray(test));

and a Kotlin function implemented like:

@JsName("aKotlinFunction")
fun aKotlinFunction(test: Set<String>) {
    console.log("aKotlinFunction called with param ${test.joinToString()}")
}