<script type='text/javascript'>
var height = screen.height;
var width = screen.width;
document.location.href='byond://?action=get_resolution&height=' + height + '&width=' + width;
</script>
Forum search IS your friend, and I found this little snippet of code that Tiberath wrote using it.
This goes a little over my head though...sorry to say. I'm not actually sure how to implement this into my code to get the player's sreen resolution. Could anyone tell me how to?