CODEWITHSUNDEEP
javascriptinheritanceprototypeprototype-chain
D_S_X
D_S_X

Reputation: 1559

Javascript : Difference between Function and Function. Prototype

If we create a function like:

function Rabbit() {}

We see that it inherits from the same object that Function inherits from i.e.

Rabbit.__proto__ === Function.__proto__

What is this higher object? If we try to log it it looks like : ƒ () { [native code] }. Shouldn't Rabbit be inheriting from Function object because it's a function? Can somebody explain where i'm wrong?

Upvotes: 1

Views: 66

Answers (2)

T.J. Crowder
T.J. Crowder

Reputation: 1074335

What is this higher object?

It's the object referenced by Function.prototype, which is also a function. It's where functions get their properties and methods from (call, apply, bind, name, and length).

That object's prototype is the object referenced by Object.prototype, which is responsible for basic object properties and methods such as hasOwnProperty and toString and, since you used it in your example, __proto__ (which is a web-only feature for backward compatibility; don't use it, use Object.getPrototypeOf instead).

Shouldn't Rabbit be inheriting from Function object because it's a function?

No, that's what Function.prototype is for.

Let's put Function, specifically, aside for a moment. Suppose you have:

function Thingy() {
}

and

let t = new Thingy();

Object.getPrototypeof(t) === Thingy.prototype will be true, because when you use new Thingy, the resulting object gets the object that Thingy.prototype points to as its prototype. This is how constructor functions and prototypes work in JavaScript.

Function is a constructor that creates functions. So the equivalent would be:

let Rabbit = new Function();

Object.getPrototypeOf(Rabbit) === Function.prototype is true. It's also true for functions that, like your Rabbit, aren't created via new Function.

Upvotes: 2

Artem
Artem

Reputation: 2047

Shouldn't Rabbit be inheriting from Function object because it's a function?

No, because it is a regular function. Every function you create this way is actually a Function object instance. See mdn.

In order to make a Function be a prototype of your object you need to explicitly specify it as a prototype of your object and create an instance using new keyword.

Upvotes: 1

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