How can we prove that javascript functions are objects?

Question

i am using

var foo = function(){}

typeof(foo) - returns function instead of Object

while javascript concept tell that all function in javascript are objects?

Answer 1

First and foremost, there's the fact that the specification explicitly states they're objects, in a lot of places, including here where it defines the term "function":

function

member of the Object type that may be invoked as a subroutine

Empirically, there are lots of ways to prove it, but one of the simplest is to assign a value to a property on it:

var foo = function() { };
foo.myProperty = "my value";
console.log(foo.myProperty); // "my value"

Or use one as a prototype (which is unusual, but possible), which proves it as only objects can be prototypes:

var foo = function() { };
var obj = Object.create(foo);
console.log(Object.getPrototypeOf(obj) === foo); // true