这个js跳转是怎么实现的

演示http://www.izhaowa.com/Proxy.php我想要他的跳转。<script language="javascript">
var isagain;
var childWin=null;
isagain="True";
window.onerror = killErrors;
function fangwen()
{
 if(isagain=="True")
 {
  box2.style.visibility = "visible";
 }
 else
 {
 yang();
 }
}
function yang2()
{
childWin =window.open("http://www.daili99.com/daili99.php",'childWin','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,width=1,height=1,left=1800,top=-800,scrollbars=no');
setTimeout( "yang3()", 5000); 
box2.style.visibility = "hidden";
box3.style.visibility = "visible";
}function yang3()
{
childWin.close();
box3.style.visibility = "hidden";
box.style.visibility = "visible";
window.location="http://www.daili99.com/daili99.php?u=Oi8vd3d3Lmdvb2dsZS5jb20=";
}function yang()
{
window.location="http://www.daili99.com/daili99.php?u=Oi8vd3d3Lmdvb2dsZS5jb20=";
box.style.visibility = "visible";
}
function killErrors() {
  window.location="http://www.daili99.com/daili99.php?u=Oi8vd3d3Lmdvb2dsZS5jb20=";
  return true;
}</script>
<body onLoad="fangwen();"  >