windows.open打開新的頁面，彈出窗口居中

<script>function changyongyu(){
  var iWidth=800;                          //彈出窗口的寬度;
   var iHeight=500;                        //彈出窗口的高度;
  var iTop = (window.screen.availHeight-30-iHeight)/2;       //獲得窗口的垂直位置;
   var iLeft = (window.screen.availWidth-10-iWidth)/2;           //獲得窗口的水平位置;
  window.open("../../../oa_api_porder_delay.php?FLOW_ID="+g_flow_id+"&RUN_ID="+g_run_id,"newwindow","height=500,width=800,top="+iTop+",left="+iLeft+",toolbar=no,menubar=no,scrollbars=yes, resizable=yes");
  }
jQuery(document).ready(function($){
  // alert("123123");
  if(g_flow_prcs=='2'){
  document.getElementById("tongbu").style.display="";
  } else {
  document.getElementById("tongbu").style.display="none";
  } 
});</script>