子对象访问父对象的更好方法？

发布于 2024-11-14 10:28:03 字数 966 浏览 1 评论 0原文

我有一些 JS 你会在下面看到。我希望内部类对象能够访问它的父对象。它需要访问父方法和属性。我这样做的方式是有效的，但我想知道是否可以在内部类构造函数中做一些事情来获取父级，而不是父级必须显式告诉子级它的父级是谁。看起来很笨重。

<html>
<body>
<script>
function ChildClass(name){
    //this.myParent=  no way of knowing .....
    this.myName=name;
    this.whereDidIComeFrom=function(){
        document.write(this.myName+ " came from " +this.myParent.dad+"<br>");
    }
}

function ParentClass(name){
    this.dad=name;
    this.myChild=new ChildClass(name+"son");
    this.myChild.myParent=this;   //only way I know for myChild to access parent
    this.myChild.whereDidIComeFrom();
}

var parentDavid = new ParentClass("David");
var parentJohn = new ParentClass("John");
</script>
</body>
</html>

运行的输出如下所示：

戴维森来自大卫
约翰逊来自约翰

我问是因为上述结构已经存在于我正在维护的项目中。我不能去重新设计整个事情。只是现在子对象必须访问它的父对象。以前不需要。如果根本不必更改父类并在子类中进行所有更改，那就太好了。但如果我所得到的基本上是“你需要做的”，那就这样吧。

原文

I have some JS you'll see below. I want the inner class object to be able to access it's parent. It needs to access parent methods and properties. The way I've done it is working, but I'd like to know if there's something I can do in the inner class constructor to get the parent, rather than the parent having to explicitly tell the child who it's parent is. It seems clunky.

<html>
<body>
<script>
function ChildClass(name){
    //this.myParent=  no way of knowing .....
    this.myName=name;
    this.whereDidIComeFrom=function(){
        document.write(this.myName+ " came from " +this.myParent.dad+"<br>");
    }
}

function ParentClass(name){
    this.dad=name;
    this.myChild=new ChildClass(name+"son");
    this.myChild.myParent=this;   //only way I know for myChild to access parent
    this.myChild.whereDidIComeFrom();
}

var parentDavid = new ParentClass("David");
var parentJohn = new ParentClass("John");
</script>
</body>
</html>

The output from running that looks like this:

Davidson came from David
Johnson came from John

I ask because the above structure already exists in the project I'm maintaining. I can't go redesigning the whole thing. It's only now that the child object has to access it's parent. Previously it hasn't needed to. It would be nice to not have to change the parent class at all and do all my changes within the child. But if what I've got is basically "what you need to do" then so be it.

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小红帽 2024-11-21 10:28:03

原则上，这已经是正确的方法了。您可以让它变得更奇特，在子级中提供一个 insertParent() 函数来检查父级引用是否已设置，但这不会改变问题的核心。

虽然数据模型中的子级只能属于一个父级，但 Javascript 并不知道这一点。例如，可能有多个父母提到同一个孩子（传闻自然界中有时会发生这种情况）。事实上，孩子不是父母的“内部阶级”。孩子和父母只是相关联的，即“他们以某种方式彼此认识”，这是一种未指定的关系，但两者都不是对方的一部分（或财产）。

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感性不性感 2024-11-21 10:28:03

我的偏好是在创建子级时将父级传递给子级，而不是在创建子级后将父级设置为单独的步骤。因此，代码几乎与您的代码完全相同，除了 ChildClass 函数上有一个额外的参数：

<script>
function ChildClass(name,myParent){
    this.myParent=myParent;
    this.myName=name;
    this.whereDidIComeFrom=function(){
        if (this.myParent != undefined && this.myParent.dad != undefined)
           document.write(this.myName+ " came from " +this.myParent.dad+"<br>");
        else
           document.write(this.myName+ " has no father<br>");
    }
}

function ParentClass(name){
    this.dad=name;
    this.myChild=new ChildClass(name+"son",this);
    this.myChild.whereDidIComeFrom();
}

var parentDavid = new ParentClass("David");
var parentJohn = new ParentClass("John");

当然，没有什么可以阻止您在创建子级后更改父级，或者通过不传递该参数来创建具有 null 或未定义父级的子级。

My preference would be to pass the parent to the child when the child is created, rather than setting the parent as a separate step after creating the child. So code almost exactly like yours except with an extra parameter on the ChildClass function:

<script>
function ChildClass(name,myParent){
    this.myParent=myParent;
    this.myName=name;
    this.whereDidIComeFrom=function(){
        if (this.myParent != undefined && this.myParent.dad != undefined)
           document.write(this.myName+ " came from " +this.myParent.dad+"<br>");
        else
           document.write(this.myName+ " has no father<br>");
    }
}

function ParentClass(name){
    this.dad=name;
    this.myChild=new ChildClass(name+"son",this);
    this.myChild.whereDidIComeFrom();
}

var parentDavid = new ParentClass("David");
var parentJohn = new ParentClass("John");

Of course there's nothing stopping you changing the parent after the child is created, or creating children with null or undefined parents by just not passing that parameter.

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