In my attempts to befriend Typescript, webpack, and Kotlin, I had a leftover

@file:JsModule

which I thought was related to what was exported and under which name.

new Kotlin Javascript project, AMD module type

@file:JsModule("kjs3")

fun demofun():Double {
    return Math.PI
}

Error:(3, 1) Kotlin: Cant put non-external declarations in file marked with {0} annotation

Error:(4, 9) Kotlin: Unresolved reference: Math

IntelliJ IDEA 2017.1 EAP

Build #IU-171.2613.7, built on January 25, 2017

Information: Kotlin: Kotlin Compiler version 1.1.0-beta-38

Works without

@file:JsModule("modulename")

I'm all hands for new tech but I want to know the motivation