How Can You Access the Parent Object of a Nested Child Object in JavaScript?

Javascript Objects: Determining Parentage

In Javascript, objects can be nested, creating a hierarchical structure. However, accessing the parent object from a nested child object can be challenging.

Consider the following nested object:

<code class="javascript">obj: { subObj: { foo: 'hello world' } };</code>

To reference the subobject within s, we use:

<code class="javascript">var s = obj.subObj;</code>

Now, we want to obtain the parent object obj using s.

Unfortunately, there is no direct mechanism to retrieve the parent object from a child object in Javascript. This is because child objects have no knowledge of their parent's existence.

Alternative Solution

One workaround is to utilize a function to establish a parent-child relationship within nested objects. Extending the code above:

<code class="javascript">var main = {
    name : "main object",
    child : {
        name : "child object",
        parent : null
    },
    init : function() {
        this.child.parent = this;
        delete this.init;
        return this;
    }
}.init();</code>

In the init function, we assign the parent object to the parent property within the child object. By calling this, we refer to the current object (ie. main) from within the nested child object. Finally, we remove the init function for code clarity.

Using this technique, we can now access the parent object from the child:

<code class="javascript">main.child.parent.name // returns "main object"</code>

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