drop dwon list with ajax

PHP:Ajax

<html>
<head>

<title>Using Ajax and XML dropdown list</title>

<script language = "javascript">
var options;
var xml_req_obj = false;
if (window.XMLHttpRequest) {
xml_req_obj = new XMLHttpRequest();
xml_req_obj.overrideMimeType("text/xml");
} else if (window.ActiveXObject) {
xml_req_obj = new ActiveXObject("Microsoft.XMLHTTP");
}
function getoptions1()
{
if(xml_req_obj) {
xml_req_obj.open("GET", "options1.php", true);
xml_req_obj.onreadystatechange = function()
{
if (xml_req_obj.readyState == 4 && xml_req_obj.status == 200) {
var xmlDocument = xml_req_obj.responseXML;
options = xmlDocument.getElementsByTagName("option");
listoptions(options);
}
}
xml_req_obj.send(null);
}
}
function getoptions2()
{
if(xml_req_obj) {
xml_req_obj.open("GET", "options2.php", true);

xml_req_obj.onreadystatechange = function()
{
if (xml_req_obj.readyState == 4 &&
xml_req_obj.status == 200) {
var xmlDocument = xml_req_obj.responseXML;
options = xmlDocument.getElementsByTagName("option");
listoptions();
}
}
xml_req_obj.send(null);
}
}
function listoptions ()
{
var loopIndex;
var selectControl = document.getElementById('optionList');

for (loopIndex = 0; loopIndex < options.length; loopIndex++ )
{
selectControl.options[loopIndex] = new
Option(options[loopIndex].firstChild.data);
}
}

function setoption()
{
document.getElementById('div_1').style.color =
options[document.getElementById
('optionList').selectedIndex].firstChild.data;
}

</script>
</head>

<body text="#000080" bgcolor="#C0C0C0">

<h1>retreive data in a Drop down list:from server </h1>

<form>
<select size="1" id="optionList" onchange="setoption()">
<option>Select a scheme</option>
</select>
<input type = "button" value = "Use color scheme 1"
onclick = "getoptions1()">
<input type = "button" value = "Use color scheme 2"
onclick = "getoptions2()">
</form>

<div id="div_1" width =100 height=100>Color this text.</div>

</body>

</html>

code option_1.php
<?
header("Content-type: text/xml");
$options = array('red', 'green', 'blue');
echo '<?xml version="1.0"?>';
echo '<options>';
foreach ($options as $value)
{
echo '<option>';
echo $value;
echo '</option>';
}
echo '</options>';
?>

code option_2.php
<?
header("Content-type: text/xml");
$options = array('black', 'white', 'orange');
echo '<?xml version="1.0"?>';
echo '<options>';
foreach ($options as $value)
{
echo '<option>';
echo $value;
echo '</option>';
}
echo '</options>';
?>