How to get the size of a JavaScript object?

Question

I want to know the size occupied by a JavaScript object.

Take the following function:

function Marks(){
  this.maxMarks = 100;
}

function Student(){
  this.firstName = "firstName";
  this.lastName = "lastName";
  this.marks = new Marks();
}

Now I instantiate the student:

var stud = new Student();

so that I can do stuff like

stud.firstName = "new Firstname";

alert(stud.firstName);

stud.marks.maxMarks = 200;

etc.

Now, the stud object will occupy some size in memory. It has some data and more objects.

How do I find out how much memory the stud object occupies? Something like a sizeof() in JavaScript? It would be really awesome if I could find it out in a single function call like sizeof(stud).

I’ve been searching the Internet for months—couldn’t find it (asked in a couple of forums—no replies).

Answer 1

function sizeOf(parent_data, size)
{
    for (var prop in parent_data)
    {
        let value = parent_data[prop];

        if (typeof value === 'boolean')
        {
            size += 4;
        }
        else if (typeof value === 'string')
        {
            size += value.length * 2;
        }
        else if (typeof value === 'number')
        {
             size += 8;
        }
        else
        {      
            let oldSize = size;
            size += sizeOf(value, oldSize) - oldSize;
        }
    }

    return size;
}


function roughSizeOfObject(object)
{   
    let size = 0;
    for each (let prop in object)
    {    
        size += sizeOf(prop, 0);
    } // for..
    return size;
}