Question

Let’s assume I have a function:

var func = function(param){return param + 1;};

Given that functions are objects, I can add properties to it:

func.prop = 'foo';

Both func(4) and func.prop should work. But now let’s say that I have an object:

var obj = {prop: 'foo'};

…and I want to make it invocable as an increment function. Is this possible?

Answer 1

I want to make [an Object] invocable as an increment function. Is this possible?

No.

Objects created by the Object constructor do not have in internal [[Call]] method and therefore can’t be called. It’s the special [[Call]] method that makes a function a function. Note that the Object constructor is a Function, but it makes plain Objects, not functions.

While Functions inherit from Object.prototype, they are created by the Function constructor. Built–in constructors have extra powers given to them by ECMA-262. 🙂