.prototype 和 [[prototype]]。 为什么 .prototype 是一个空对象？

Question

I am actually very confused with prototypes right now despite reading most articles on StackOverflow.

function Foo() {

}

Foo.prototype.speak = function() {
    console.log('Foo');
};

function Bar() {

}

console.log(Bar.prototype); // {}

Bar.prototype = Object.create(Foo.prototype);

console.log(Bar.prototype); // {} ----- (1)

Bar.prototype.speak = function() {  // ----------(2)
    console.log('Bar');
};   

console.log(Bar.prototype); // { speak: [Function] }  ----- (3)

Question:

1) Why is (1) an empty object after Object.create . Shouldn't it turn an object with a speak method from Foo ?

2) What am I actually changing on (2) ?? The Bar object or the prototype object ? What is actually happening?

3) What's happening on (3) .

4) How is [[prototype]] involved in all of this? What I do know is [[prototype]] is used for look ups if the current object does not contain a property.

Just to be sure, .prototype !== [[prototype]] but [[prototype]] === __proto__ ?

Sorry if this is a duplicate. Because I can't seem to answer those questions despite multiple similar questions.

Answer 1

You can't change the prototype of a function/object by simply trying to assign it. You need to set it at the time of object creation or you should use ES6 features to change it.

So, Bar.prototype = Object.create(Foo.prototype); doesn't make any sense.

[[prototype]] is the internal representation of the real prototype of an object.

Probably you should re-arrange your test case based on these fundamentals and seek explanation.