is there a writeup of how null/undefined is being ...

# javascript

[Bernhard]

is there a writeup of how null/undefined is being handled? it looks as if "var?.value" returns null and not undefined as the JS counterpart (which is great btw); are all undefined values from native JS APIs coerced into nulls? I know there's "undefined" as well as Nothing?

[turansky]

fun f(a: Any?) {
   a === null // is null
   a === undefined // is undefined 
}

[turansky]

are all undefined values from native JS APIs coerced into nulls?

From JS API you will receive original values

[turansky]

Single exception - external functions, which return Unit

[Bernhard]

thank you

[Edoardo Luppi]

Also know that void 0 is used to represent undefined.
A void 0 variable is passed to external functions with optional parameter, for example.

external class Example {
    constructor(one: String, two: String = definedExternally, three: String)
}

val e = Example(one = "o", three = "t")

Translates to

var e = new Example('o', VOID, 't');