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122

In an array of named objects in javascript - are the names accessible?

rated 0 times [ 126] [ 4] / answers: 1 / hits: 15297 / 9 Years ago, wed, may 27, 2015, 12:00:00

If we create some objects, and fill an array with those objects, are the names stored within the array, or only the properties of the object?
I guess this may be trivial, but I haven't been able to find an answer.

var boxA = {color: red, width: 100};

var boxB = {color: yellow, width: 200};

var boxC = {color: blue, width: 300};



boxArray = [boxA, boxB, boxC];



for (var i = 0; i < boxArray.length; i++) {



    //****

    // What code do we insert here to log

    // boxA

    // boxB

    // boxC

    //****



}

Of course, it is a trivial workaround to add

boxA.box = boxA;

etc and then call

console.log(boxArray[i].box);

But is that really necessary?

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sergiobrayanc

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3 Years ago

answered 9 Years ago kylanalis · Accepted Answer

No, that does not work like that.

The variable name is a reference to an object in a heap area of memory managed by JS automatically for you.

In details it means that:

var boxA = {color: red, width: 100};

this statement:

Creates an object in the heap

Associates a local symbol boxA with that object.

So the object is referenced by one variable yet.

var boxArray = [boxA];

here:

An array with one element is created. That element contains a reference to an object. A copy of the reference to be precise. So, the same original object is referenced twice now.

A boxArray is assigned a reference to the array, which is also placed in the heap.

To summarize: the variable names exist only in code listing for developers to easier reason about some objects in memory, instead of operating with memory addresses (which would be horrible).