MyClass.prototype = new Object（）和MyClass.prototype = Object之间的区别 [英] Difference between MyClass.prototype = new Object() and MyClass.prototype = Object

问题描述

任何人都可以告诉我，在Javascript中的区别

could anyone please tell me, where in Javascript the difference between

MyClass.prototype = new Object(); //or ... = {}

和

MyClass.prototype = Object;

是？如果结果没有差异，哪一个是最佳实践方式？

is? And if there is no difference in the result, which one is the best-practise-way-to-go?

推荐答案

你的前两个例子是完全等价的：

Your first two examples are completely equivalent:

MyClass.prototype = new Object(); // empty object
MyClass.prototype = {}; // empty object

您的第三个示例无效，因为您要分配给 MyClass.prototype 对对象的引用构造函数，它是一个函数，而不是一个新对象。

Your third example is not valid, since you are assigning to the MyClass.prototype a reference to the Object constructor, and it's a function, not a new object.

我个人更喜欢第二个，对象 literal 或初始化程序语法：

I personally prefer the second, the object literal or initialiser syntax:

MyClass.prototype = {prop1: 'value', prop2: 'value2'};
//...
MyClass.prototype.foo = 'bar';
MyClass.prototype.method1: function () {/**/};

编辑：为了回应您的评论，空对象文字 {} 基本上相当于 new Object（）因为：

In response to your comment, an empty object literal { } essentially equivalent to new Object() because of this:

生产ObjectLiteral：{}是
评估如下：

The production ObjectLiteral : { } is evaluated as follows:

1. 创建一个新对象好像通过表达式new Object（）。


2. 返回结果（1）。

有关详细信息，请查看 ECMAScript语言规范（pdf）。

For more details check the 11.1.5 section (Object Initialiser) of the ECMAScript Language Spec (pdf).

编辑：第三个例子赢了'产生任何错误，但一点也不好，例如，如果你之后扩展MyClass.prototype，你可以很容易地破坏Object构造函数：

The third example won't produce any errors, but is not good at all, for example you can easily clobber the Object constructor function if you extend afterward the MyClass.prototype:

MyClass.prototype = Object;
MyClass.prototype.foo = 'bar';

Object.foo === MyClass.prototype.foo; // true

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