Simple AJAX

This a simple AJAX code. now i'm using PHP as server side programming language. there is 3 source, they are index.html, script.js and process.php

index.html

< !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
< html >
< head>
< title>Simple AJAX< /title>
< script type="text/javascript" src="script.js">< /script>
< /head>
< body onload='process()'>
Input Tutorial:
< input type="text" id="myName" />
< div id="divMessage" />
< /body>
< /html>



process.php

< ?php
// create XML output
header('Content-Type: text/xml');
// create XML header
echo '';
// create the element
echo '';
// get paramater
$name = $_REQUEST['name'];
// create output
$userNames = array('AJAX', 'WEB 2.0', 'ASP.NET');
if (in_array(strtoupper($name), $userNames))
echo 'This tutorial about ' . htmlentities($name) . '!';
else if (trim($name) == '')
echo 'Please input tutorial that you want';
else
echo ' Sorry, there is no tutorial about '.htmlentities($name).'!';
echo '';
? >

script.js

var xmlHttp = createXmlHttpRequestObject();
// Create Request Object
function createXmlHttpRequestObject()
{
var xmlHttp;
// if Internet Explorer
if(window.ActiveXObject)
{
try
{
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e)
{
xmlHttp = false;
}
}
// if Mozilla or another browser
else
{
try
{
xmlHttp = new XMLHttpRequest();
}
catch (e)
{
xmlHttp = false;
}
}

if (!xmlHttp)
alert("Error creating the XMLHttpRequest object.");
else
return xmlHttp;
}
// Create asynchronous HTTP request with XMLHttpRequest object
function process()
{

if (xmlHttp.readyState == 4 || xmlHttp.readyState == 0)
{
// get parameter input by user
name = encodeURIComponent(document.getElementById("myName").value);
var param='name='+name;

// connection to server
xmlHttp.open("POST", "process.php", true);
xmlHttp.onreadystatechange = handleServerResponse;
xmlHttp.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
// Create request to server
xmlHttp.send(param);
}
else

setTimeout('process()', 1000);
}


function handleServerResponse()
{

if (xmlHttp.readyState == 4)
{

if (xmlHttp.status == 200)
{

xmlResponse = xmlHttp.responseXML;


xmlDocumentElement = xmlResponse.documentElement;

helloMessage = xmlDocumentElement.firstChild.data;

document.getElementById("divMessage").innerHTML ='' + helloMessage + '';
// restart sequence
setTimeout('process()', 1000);
}

else
{
alert("There was a problem accessing the server: " + xmlHttp.statusText);
}
}
}