มีวีธีเรียกใช้ javascript แบบไม่ผ่าน event ไหม ตรับ

<script language=Javascript>
         function Inint_AJAX() {
            try { return new ActiveXObject("Msxml2.XMLHTTP");  } catch(e) {} //IE
            try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch(e) {} //IE
            try { return new XMLHttpRequest();          } catch(e) {} //Native Javascript
            alert("XMLHttpRequest not supported");
            return null;
         };
 function dochange2(src, val) {
							var req = Inint_AJAX();
							req.onreadystatechange = function () {
									 if (req.readyState==4) {
												if (req.status==200) {
														 document.getElementById(src).innerHTML=req.responseText; //รับค่ากลับมา
												}
									 }
							};
							req.open("GET", "planPO1.php?data="+src+"&val="+val); //สร้าง connection
							req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=utf-8"); // set Header
							req.send(null); //ส่งค่า
				 }
 window.onLoad=dochange2('PO', -1);
</Script>

	echo " <input type='text' name = 'testPO' id = 'testPO' value='".$_SESSION["PONR"]."' onFocus = \"dochange2('Color', document.getElementById('testPO').value);\" >";
							if($_SESSION["PONR"]!=null){
					 ?>
					 <script language=Javascript>
						call.dochange2('Color',document.getElementById('testPO').value);
					 </script>
					 <?php
				 	}