팝업창 화면 크기에 맞게 띄우기

<script language="javascript" type="text/javascript">
function resizeWindow(){
  if(document.all)
  { 
    var x = (document.body.scrollWidth  > 1000) ? 1000 : document.body.scrollWidth;
    var y = (document.body.scrollHeight > 700)  ? 700  : document.body.scrollHeight;
    x -= document.body.clientWidth;
    y -= document.body.clientHeight;
    window.resizeBy(x, y);
  }
}

resizeWindow();
</script>