CODEWITHSUNDEEP
javascriptperformance
Praveen Prasad
Praveen Prasad

Reputation: 32107

Is this memory leak?? In javascript

(function () {

    //create object with two initail properties
    var obj = {};
    obj.a = { a1: 1, a2: 2 };
    obj.b = { b1: 1, b2: 2 };

    //create a new property 'c' and refer property 'a' to it
    obj.c = obj.a;

    //cyclic reference
    obj.a = obj.b;
    obj.b = obj.a;



    //this function removes a property from the object
    // and display all the three properties on console, before and after.
    window.showremoveshow = function () {

        console.log(obj.a, '-----------a');
        console.log(obj.b, '-----------b');
        console.log(obj.c, '-----------c');

        //delete proprty 'a'
        delete obj.a;

        //comes undefined
        console.log(obj.a, '-----------a'); 

        //displays b
        console.log(obj.b, '-----------b'); 

        //still displays the initial value obj.a
        console.log(obj.c, '-----------c'); 
    }

})();

Now: After deleting obj.a and checking the value of obj.c we find that obj.c still refers to the initial value of obj.a, however obj.a itself doesnt exist. So is this a memory leak. As obj.a is deleted and its initial value still exist.

Edit: is this means,like although we removed the property(obj.a) its values exist even after. Which can be seen in obj.c.

Upvotes: 0

Views: 284

Answers (2)

minond
minond

Reputation: 29

That's not a memory leak. obj.c only holds a copy of the value assigned to obj.a.

Upvotes: 1

Nanne
Nanne

Reputation: 64399

Delete only removes the reference, so that's what happens. Complete answer also here:

Deleting Objects in JavaScript

And if you have some time on your hands, check this :)

http://perfectionkills.com/understanding-delete/

Upvotes: 0

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