Javascript assigning prototype confusion

Question

var object1 = {
    name: "abc",
    age: 21
}

var Object2 = function() {}
Object2.prototype = object1;
Object2.prototype.hello = function() {
    console.log("Hello");
}

var obj = Object.create(object1);
for (var prop in obj) {
    console.log(prop + ": " + obj[prop]);
}

The output of this code is:

name: abc
age: 21
hello: function () {
    console.log("Hello");
}

Obj is created by setting its prototype as object1, which doesn't have the 'hello' function, so why is it listed in the output? If I comment out 'Object2.prototype = object1;', the 'hello' function no longer shows in the output. I don't see how obj and Object2 are connected. Can anyone please explain what's happening here?

Answer 1

After this line...

Object2.prototype = object1;

... both Object2.prototype and object1 refer to the same object. Hence this line...

Object2.prototype.hello = function() { // ...

... assigns a new property to the object referred by object1.

I don't see how obj and Object2 are connected.

With var obj = Object.create(object1), you create an object which __proto__ property points to object1. The latter, as we established, is actually the same object Object2.prototype points to.

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I.e setting Object2.prototype to an object without them both referring to the same object?

If you only want Object2.prototype to copy properties from object1, just clone an object.