Good day to every one
im trying to centre the pop up window and not sure how to make it.
below is the script

HTML Code:
<script language="javascript">
function target_popup(form) {
    window.open('', 'formpopup', 'width=900,height=400, resizeable,scrollbars,');
    form.target = 'formpopup';
}
</script>

HTML Code:
 <form id="theform" name="order" method="post" action="confirm.php" onsubmit="target_popup(this)" enctype="multipart/form-data" style="position:absolute; left:0px; top:0px">
Thank you