将原型添加到对象文字中 [英] Adding a prototype to an object literal

问题描述

我有一些对象，比如 son ，我想继承另一个对象 father 。

I have some object, say son, which I'd like to inherit from another object father.

当然我可以为父做一个构造函数，比如

Of course I can make a constructor function for father, like

Father = function() {
  this.firstProperty = someValue;
  this.secondProperty = someOtherValue;
}

然后使用

var son = new Father();
son.thirdProperty = yetAnotherValue;

但这不是我想要的。由于 son 将具有许多属性，因此将子声明为对象文字将更具可读性。但后来我不知道如何设置其原型。

but this is not exactly what I want. Since son is going to have many properties, it would be more readable to have son declared as an object literal. But then I don't know how to set its protoype.

做类似的事情

var father = {
  firstProperty: someValue;
  secondProperty: someOtherValue;
};
var son = {
  thirdProperty: yetAnotherValue
};
son.constructor.prototype = father;

不起作用，因为原型链似乎是隐藏的而不关心构造函数的更改。原型。

will not work, as the prototype chain seems to be hidden and not care about the change of constructor.prototype.

我想我可以在Firefox中使用 __ proto __ 属性，例如

I think I can use the __proto__ property in Firefox, like

var father = {
  firstProperty: someValue;
  secondProperty: someOtherValue;
};
var son = {
  thirdProperty: yetAnotherValue
  __proto__: father
};
son.constructor.prototype = father;

但据我所知，这不是该语言的标准功能，它更好不要直接使用它。

but, as far as I understand, this is not a standard feature of the language and it is better not to use it directly.

有没有办法为对象文字指定原型？

推荐答案

你是对的， __ proto __ 是一个非标准的属性，你只有两种标准方式设置一个新对象的 [[Prototype]] ，是：

You're right, __proto__ is a non-standard property, and the only two standard ways you have to set a new object's [[Prototype]], are:

• 通过使用构造函数和 new 运算符（如您所述）。


• 使用ECMAScript 5 Object.create 方法。

• Through the use of a constructor and the new operator (as you already mention).
• Using the ECMAScript 5 Object.create method.

Object.create 不是广泛支持（适用于IE9Pre3 +，Firefox 3.7Alpha +，Chrome 5+ Safari 5+， Rhino 1.7），但在某些时候所有实现都符合ES5规范。

Object.create is not widely supported yet (works on IE9Pre3+, Firefox 3.7Alpha+, Chrome 5+ Safari 5+, Rhino 1.7), but at some point all the implementations will conform the ES5 spec.

它可以有两个参数，第一个是将用作的对象新对象的 [[Prototype]] ，第二个是另一个可以描述自己属性的对象（与你使用的结构相同 Object.defineProperties ）。

It can take two arguments, the first one is the object that will be used as the [[Prototype]] of the new object, and the second one, is another object where the own properties can be described (in the same structure that you would use Object.defineProperties).

例如：

var father = {
  firstProperty: 1,
  secondProperty: 2
};

var son = Object.create(father, {
  thirdProperty: {
    value: 'foo'
  }
});

father.isPrototypeOf(son); // true
son.firstProperty; // 1

儿子内部 [[Prototype]] 属性将引用 father ，它将包含一个名为的值属性thirdProperty 。

The son internal [[Prototype]] property will refer to father, and it will contain a value property named thirdProperty.

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