Unfortunately you can't quite reverse engineer .call -- at least not as JavaScript -- simply because of how 'this" is handled or handling the multiple parameters back into actual parameters -- at least not without also reverse engineering "Function.apply". (which I always found more useful).
NOT that said command has ANYTHING to do with "judge the type of the JS object"... I have ZERO clue what you even mean by that as that has next to nothing to do with what a .call() does.
Makes me wonder if you ACTUALLY know what it does.