__proto__ VS. prototype in JavaScript

Question

This figure again shows that every object has a prototype. Constructor function Foo also has its own __proto__ which is Function.prototype, a

Answer 1

This is a very important question relevant to anyone who wants to understand prototypical inheritance. From what I understand, prototype is assigned by default when an object is created with new from a function because Function has prototype object by definition:

function protofoo(){
}
var protofoo1 = new protofoo();
console.log(protofoo.prototype.toString()); //[object Object]

When we create an ordinary object without new, ie explicitly from a function, it doesn't have prototype but it has an empty proto which can be assigned a prototype.

var foo={
  check: 10
};
console.log(foo.__proto__); // empty
console.log(bar.prototype); //  TypeError
foo.__proto__ = protofoo1; // assigned
console.log(foo.__proto__); //protofoo

We can use Object.create to link an object explicitly.

// we can create `bar` and link it to `foo`
var bar = Object.create( foo );
bar.fooprops= "We checking prototypes";
console.log(bar.__proto__); // "foo"
console.log(bar.fooprops); // "We checking prototypes"
console.log(bar.check); // 10 is delegated to `foo`