Question

What is a memory efficient way to link two objects? If you store objects using two arrays with corresponding index values the object won’t be released from memory.

The implementation should look like the following.

var obj ={};
var linkedobj = getLinkedObject(obj);
var obj2 ={}
var linkedobj2 = getLinkedObject(obj2);            

Answer 1

Objects are general containers

If all you want to do is associate one object with another one, then why not have them point to one another?

var obj = {};
var obj2 = {};

obj.linkedObject = obj2;
obj2.linkedObject = obj;

This would a normal thing to do, and doesn’t have bad implications on memory.

Releasing memory

If you are asking about holding a table full of object references, you are correct that the object will not disappear until all of the live references to it are gone. Javascript has a garbage collector, and as long as your table or array has a good reference, it will be backed by memory for you. If you give an object to a table and then want it to be deleted from memory entirely, you can simply remove it from your table also. You could also just remove the table, assuming it doesn’t need to hold anything else.

If you are determined to have a getLinkedObject function return an object for another object, you can still allow the objects to each hold the associate reference.

function getLinkedObject(anObject) {
    return anObject.linkedObject;
}

This would probably be accompanied by a counterpart:

function linkObjects(anObject, anotherObject) {
    anObject.linkedObject = anotherObject;
    anotherObject.linkedObject = anObject;
}

Doing this allows you to worry a little less about memory management, which in Javascript (a high-level, dynamic environment with a garbage collector) is typically appropriate.