Every Object is a function and every function is Object - Which is Correct?

Question

I was reading this link JavaScript_syntax

This seems to be cyclic - that every function is an Object and every Object itself is a function. Which is the atomic one? Can someone explain in a better way?

Answer 1

Every function is an object. Objects can contain functions (methods) but an object is not necessary a function.

Answer 2

Every function is an Object.

I'm not an javascript expert, but I cannot see how every Object is a function. (I can see how every object could be a function, but that's different)

Answer 3

It would be better to say that in JavaScript everything can be treated as an object, that includes primitive types as well as functions types; what the JavaScript interpreter does is that it automatically promotes your primitives and functions to their object wrapper types when you interact with them.

There is also a Function object, an a number of equivalent Wrappers for the other primitives in JavaScript, that means that you can even call methods on functions instances, like:

myFunction(someArg).call(this)

That being said, not every object is in fact a function.

Answer 4

1. Anything that is not a primitive type (undefined, null, number, string, boolean) is an object (or an instance) in JavaScript. That means function inherits from object.

2. Object instances can contain more instances which can be functions. That's what we call a "method" (since it has an automatic this variable).

3. Since you can't "call" every Object instance, not every object is a function.

Answer 5

Also Function is always a property of an object.

This mean that all functions in JavaScript is always bound to an object. If you don't specify an object to bind a function to it's bound to the window object (Also called global functions)

..fredrik

Answer 6

As others have said, functions are objects that can be passed around by reference like other js objects. Not all objects are functions, only those that are declared as such.

You will often see methods declared like so:

var myFunc = function(foo, bar) {
    ...
};

This is to reinforce the fact that the mthod is a function object and as such it is a property of the object where it is defined, just like any other variable you might define with var.

This is the foundation of the most important feature in javascript, closure.