proto VS prototype in JavaScript

Question

The figure in the image below once again shows me that every object has a prototype. Constructor function Foo also has its own __proto__ which is Function.prototype, and which in turn also references via its __proto__ property again to the Object.prototype. Thus, repeat, Foo.prototype is just an external property of Foo which refers to the prototype of b and c objects.

var b = new Foo(20); var c = new Foo(30);

What are the differences between __proto__ and prototype?

Answer 1

To answer your query, the __proto__ is the actual object that is used in the lookup chain to resolve methods whereas, the prototype is the object that is used to build __proto__ when you create an object with new:

( new Foo ).__proto__ === Foo.prototype; 
( new Foo ).prototype === undefined;