Um.. this is an parameter to a method.

# getting-started

[deinspanjer]

Um.. this is an parameter to a method.

[mkevin3]

for this line
val js: Invocable = jsEngine as Invocable you can do
val js = jsEngine as Invocable instead

All the Pair("Hi".toJson, null) can be "Hi".toJson to null which is a shorter Pair creation syntax