在这个例子中如何得到父亲的属性？

Question

var father = {
  b: 3,
  c: 4
};

var child = Object.create(father);
child.a = 1;
child.b = 2;

child.b 现在是 2，chrome devtools 显示 child 有 b 属性是继承的。我如何找到它，为什么它没有被覆盖？

Answer 1

javascript 中的对象与其他名为 __proto__ 的对象有一个 link。您可以使用以下方法获取父对象的属性：

var father = {
  b: 3,
  c: 4
};

var child = Object.create(father);
child.a = 1;
child.b = 2;
console.log(child);//prints Object { a: 1, b: 2 }
console.log(child.__proto__);//prints Object { b: 3, c: 4 }

You can use this secret property for learning purposes, but it's not a good idea to use it in your real scripts because it does not exist in all browsers (notably Internet Explorer), so your scripts won't be portable.

Be aware that __proto__ is not the same as prototype, since __proto__ is a property of the instances (objects), whereas prototype is a property of the constructor functions used to create those objects. [ 1 ]

我强烈建议使用 Object.getPrototypeOf():

var father = {
  b: 3,
  c: 4
};

var child = Object.create(father);
child.a = 1;
child.b = 2;
console.log(child);//prints Object { a: 1, b: 2 }
console.log(Object.getPrototypeOf(child));//prints Object { b: 3, c: 4 }

参考

Object-Oriented JavaScript - Second Edition [ 1 ]

Answer 2

这是一种方式，但您需要多阅读一点有关阴影和继承以及原型链的内容。

Object.getPrototypeOf(child).b

在这个例子中如何得到父亲的属性？

How to get the property of father in this example?

javascript

javascript-objects