[[Prototype]] vs原型：..有什么区别？ （MyCons .__ proto__ === MyCons.prototype）等于FALSE [英] [[Prototype]] vs prototype: ..what is the difference? (MyCons.__proto__ === MyCons.prototype) equals FALSE

问题描述

这里似乎有区别......

It seems like there is a difference here...

假设我们有函数MyConstructor（）{}

MyConstructor的 [[Prototype]] 是 Function.prototype ，不 MyConstructor.prototype。

MyConstructor's [[Prototype]] is Function.prototype, not MyConstructor.prototype.

其他（非标准/console.log-able）字样：
$
MyConstructor .__ proto __ 不是 MyConstructor的 MyConstructor.prototype

In other (non-standard/"console.log-able") words:
MyConstructor.__ proto__ is not MyConstructor's MyConstructor.prototype

尝试这个：

function MyConstructor() {};
(MyConstructor.__proto__ === MyConstructor.prototype); //false?! why?

为什么会这样？有人可以向我解释差异吗？

Why is this so? Can someone explain it to me the difference?

推荐答案

想想这样吗。 MyConstructor 是一个函数对象，因此它是由 Function 创建的;因此它的 [[Prototype]] （或 __ proto __ ）与 Function.prototype <相同/ code>。

Think of it like this. MyConstructor is a function object, so it was created by Function; therefore its [[Prototype]] (or __proto__) is identical to Function.prototype.

以同样的方式， var myObj = new MyConstructor（）创建一个对象 myObj [[Prototype]] 与 MyConstructor.prototype相同。

In the same way, var myObj = new MyConstructor() creates an object myObj with a [[Prototype]] identical to MyConstructor.prototype.

换句话说，函数有一个 prototype 属性，当你用<调用函数时code> new ，他们将构造一个对象，其 [[Prototype]] 与构造函数的相同原型属性...但是函数的原型属性与它的 [[Prototype]]不是一样的（或 __ proto __ ）属性，因为函数遵循与其他对象相同的规则并获取其内部 [[Prototype]] 来自构造它的函数的属性（它总是函数，顺便说一句。）

To put it another way, functions have a prototype property, and when you invoke functions with new, they will construct an object having a [[Prototype]] identical to the constructor function's prototype property... however a function's prototype property is not the same thing as its [[Prototype]] (or __proto__) property, because a function follows the same rules as other objects and gets its internal [[Prototype]] property from the function that constructed it (which is always Function, incidentally).

为了进一步解释， [[Prototype]] 和 prototype 有完全不同的用途。在解析对象的属性时使用 [[Prototype]] 。如果一个对象没有属性，则检查其 [[Prototype]] ，然后检查该对象的 [[Prototype]] ，依此类推，直到找到一个属性或者你到达原型链的末尾。

To explain further, [[Prototype]] and prototype have entirely different purposes. [[Prototype]] is used when resolving an object's properties. If an object doesn't have a property, its [[Prototype]] is checked, and then that object's [[Prototype]], and so on, until either a property is found or you hit the end of the prototype chain.

相比之下，原型是将 [[Prototype]] 属性分配给对象的机制，因为除了非对象之外，您无法直接访问它们标准 __ proto __ 属性。

In contrast, prototype is the mechanism by which you assign [[Prototype]] properties to objects, since you can't access them directly other than with the non-standard __proto__ property.

由于函数是对象，它们都有一个 [[Prototype]] 内部属性，用于解析属性使用普通对象和 prototype 属性，该属性被指定为由 [[Prototype]] 构造的新对象功能。

Since functions are objects, they have both a [[Prototype]] internal property, used to resolve properties as with normal objects, and a prototype property, which is assigned as the [[Prototype]] of new objects constructed by the function.

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