สอบถาม ถ้าต้องการให้ ajax ทำงาน window.location ในไฟล์ที่ขอไปต้องทำอย่างไรครับ

<script language="javascript">
var HttPRequest = false;
	   function doCallAjax() {
		  HttPRequest = false;
		  if (window.XMLHttpRequest) { // Mozilla, Safari,...
			 HttPRequest = new XMLHttpRequest();
			 if (HttPRequest.overrideMimeType) {
				HttPRequest.overrideMimeType('text/html');
			 }
		  } else if (window.ActiveXObject) { // IE
			 try {
				HttPRequest = new ActiveXObject("Msxml2.XMLHTTP");
			 } catch (e) {
				try {
				   HttPRequest = new ActiveXObject("Microsoft.XMLHTTP");
				} catch (e) {}
			 }
		  } 
		  
		  if (!HttPRequest) {
			 alert('Cannot create XMLHTTP instance');
			 return false;
		  }
	
		  var url = 'system/check_login.php';
		  var pmeters = "user=" + encodeURI( document.getElementById("user").value)+ "&pass=" + encodeURI(document.getElementById(encodeURI("pass")).value)+ "&forever=" + encodeURI(document.getElementById(encodeURI("forever")).value);

			HttPRequest.open('POST',url,true);

			HttPRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
			HttPRequest.setRequestHeader("Content-length", pmeters.length);
			HttPRequest.setRequestHeader("Connection", "close");
			HttPRequest.send(pmeters);
			
			HttPRequest.onreadystatechange = function()
			{

				if(HttPRequest.readyState == 3)  // Loading Request
				{
					document.getElementById("display").innerHTML = '<img src="images/loading.gif" width="16" height="16">';
				}

				if(HttPRequest.readyState == 4) // Return Request
				{
					if(HttPRequest.responseText == 'Y')
					{
						window.location = 'index.php';
					}
					else
					{
						document.getElementById("display").innerHTML = HttPRequest.responseText;
					}
				}
			}
	   }

ob_start(); 
session_start();
include "connection_db.php";
	$strSQL = "SELECT * FROM customer WHERE user = '".trim($_POST['user'])."' and pass = '".trim($_POST['pass'])."'";
	$objQuery = mysql_query($strSQL);
	$objResult = mysql_fetch_array($objQuery);
	if(!$objResult)
	{
			echo "Username หรือ Password ไม่ถูกต้อง";
	}
	else if($_POST['forever']=='on')
	{
		setcookie("id",$objResult["number"], time()+3600*24*365,"/");
		setcookie("status", $objResult["status"], time()+3600*24*365,"/");
		if($objResult["status"] == "ADMIN")
			{
			echo "<script>window.location.href= '../home.php'</script>";
			}
			else
			{
			echo "<script> window.location.href = '../homevdo.php'</script>";
			}
	}
	else {
				$_SESSION['id'] = $objResult["number"];
				$_SESSION['status'] = $objResult["status"];
				session_write_close();
				
				if($objResult["status"] == "ADMIN")
				{
					echo "<script> window.location.href = '../home.php'</script>";
				}
				else
				{
					echo "<script> window.location.href = '../homevdo.php'</script>";
				}
			}
			mysql_close();
		ob_end_flush();