在obj.prototype = new ParentObj（）之后消失的对象方法;在JavaScript中

问题描述

我正在尝试使用JavaScript继承对象。看一下这个例子：

I am trying inherit objects in JavaScript. Take a look at this example:

var BaseObject = function() {
};

var ChildObject = function() {
};

ChildObject.prototype.childMethod = function() {
};

ChildObject.prototype = new BaseObject();
ChildObject.prototype.constructor = ChildObject();

但是，只要我做原型继承，childMethod（）就会消失。我在这里做错了什么？

However, as soon as I do prototypal inheritance, the childMethod() disappears. What am I doing wrong here?

推荐答案

当你将原型分配给BaseObject并且BaseObject的原型没有childMethod方法时，你会覆盖原型。

You are overwriting the prototype when you assign it to BaseObject and BaseObject's prototype has no childMethod method.

要获得所需的行为，您必须在将原型分配给BaseObject后添加childMethod：

To get the desired behavior you have to add childMethod after assigning the prototype to BaseObject:

var BaseObject = function() {
};

var ChildObject = function() {
};


ChildObject.prototype = new BaseObject();
ChildObject.prototype.constructor = ChildObject;
ChildObject.prototype.childMethod = function() {
    return 'childMethod';
};
c = new ChildObject();
alert(c.childMethod());

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