设置“构造函数”的优点在于， “原型”中的属性 [英] Advantages of setting the "constructor" Property in the "prototype"

问题描述

在JavaScript原型继承中，添加prototype.constructor属性的目的是什么。让我以一个例子解释。

In JavaScript Prototype inheritance, what is the goal of adding prototype.constructor property. Let me explain with an example.

var Super = function() {
    this.superProperty = 'Super Property'
}
var Sub = function() {
    this.subProperty = 'Sub Property'
}

Sub.prototype = new Super();
Sub.prototype.constructor = Sub; // advantages of the statement

var inst = new Sub();

在添加Sub.prototype.constructor = Sub时，以下行总是返回true。

The following lines return always true in all case, when adding Sub.prototype.constructor = Sub or not.

console.log(inst instanceof Sub)   // true
console.log(inst instanceof Super) // true

我想，当获取新实例时，或者当和/或如何时，它可能会有用？

I guess, it may be useful when getting new instances but when and/or how?

。

推荐答案

只需正确地重置构造函数属性，用于构造对象的函数。

It's just to properly reset the constructor property to accurately reflect the function used to construct the object.

Sub.prototype = new Super();

console.log(new Sub().constructor == Sub);
// -> 'false' 

Sub.prototype.constructor = Sub;
console.log(new Sub().constructor == Sub);
// -> 'true' 

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