javascript:find screen resolution when having multiple monitors

I am using this piece of code to determine the client screen resolution, and then logging it

<input type="hidden" id="DFF63C7E-FB32-49AE-8ADA-3AB5C4834FB0" name="DFF63C7E-FB32-49AE-8ADA-3AB5C4834FB0"/>
 <input type="hidden" id="565C07CF-0D37-41DE-B47D-A247E9BD231B" name="565C07CF-0D37-41DE-B47D-A247E9BD231B" />
<script type="text/javascript" language="javascript">
         document.getElementById("DFF63C7E-FB32-49AE-8ADA-3AB5C4834FB0").value = screen.width;  
         document.getElementById("565C07CF-0D37-41DE-B47D-A247E9BD231B").value = screen.height;

It worked OK when testing in my localhost, but what I found out from the production logs was that the screen resolution was always 480x640. Does anyone know why this happens ?

And I did some more digging and found that I could change the resolution of my primary monitor and regardless of whether I open my browser in primary/secondary monitor, it would always give me the resolution of the primary monitor.

Is there any way to get the screen resolution based on which monitor the browser gets opened ?

And obviously the next question is, if the resolution changes midway (say from control panel) or moving the browser from one to another, is there a way to detect/update it with JS ?

  1. It might be that your production PC really has 640*480 screen resolution. Is there a reason to doubt it?
  2. Javascript has no means getting out of its virtual machine to take even a glance on the real host, so you must implement your update mechanism by the same means you detect the screen resolution, whatever it is.

Add the following line to your page.

window.moveTo(0,0); window.resizeTo(screen.availWidth,screen.availHeight);" 

it will resize your window to full width and height..

for example use

<body onload="window.moveTo(0,0); window.resizeTo(screen.availWidth,screen.availHeight);" >

Try this to get the dimensions of the window instead:

window.document.width //Get the width
window.document.height //Get the height