关于在MDN上标题为“Object.create（）”的文档中的javascript继承的困惑

Question

I've been reading the this document at Mozilla Developer Network. In this document, a way for inheritance is defined as follows:

// subclass extends superclass
Rectangle.prototype = Object.create(Shape.prototype);
Rectangle.prototype.constructor = Rectangle;

The question is, while assigning the Shape prototype to Rectangle prototype, why do I create a new Object as given in this code snippet? :

Rectangle.prototype = Object.create(Shape.prototype);

Why couldn't I assign the inheritance as this code snippet? :

Rectangle.prototype = Shape.prototype;

Answer 1

Because then anything you add to Rectangle.prototype will also be in Shape.prototype .
You'll also have the wrong constructor property.

You want Rectangle.prototype to inherit all members from Shape.prototype , but still be an independent object that can have its own members.