Increase or decrease popup window height and width

Hi All,

I am opening a popup window using window.open method where i am passing height and width
parameters to window.open method.
Window contains one div tag.

Now my requirement is like :-
When div size increases/decreases then window size increases/decreases accordingly.

Below is the code:-

var pop_window = null;
function Open_Popup_Window(URL, Height, Width) 
{
    try {       
        pop_window = window.open(URL, "_blank", 'status=no, resizable=1, toolbar=no,menubar=no,scrollbars=no,location=no,directories=no, width=' + Width + ', height=' + Height + ');
    }
    catch (e) {
        console.log(e.message);
    }

    return pop_window;
}

function ResizeWindow()
{
    //alert('ResizeWindow' + pop_window);
    if (pop_window)
        pop_window.resizeTo(500, 650);
}

Above js function is written in js file.
I tried with resizeTo method with window object but it's getting null when calling ResizeWindow function from different page then pop_window object is getting null.