A Working AJAX Request
The HTML / Javascript
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script>
//***********************************
//***********************************
//********** AJAX HANDLERS **********
//***********************************
//***********************************
//<div id='ajax_area1'>THIS WILL BE REPLACED</div>
//Setup to make an HTTP POST Ajax request
AjaxRequest1Parameters = "request_type=get_image_to_show"; //<<<<<SET PARAMETER TO POST (id1=val1&id2=val2 for multiple parameters)
AjaxRequest1 = new ajaxRequest();
AjaxRequest1.open("POST", "ajax.php", true); //<<<<<SET THE FILE TO POST THE REQUEST TO
AjaxRequest1.setRequestHeader("Content-type", "application/x-www-form-urlencoded; charset=UTF-8");
AjaxRequest1.setRequestHeader("Content-length", AjaxRequest1Parameters.length);
AjaxRequest1.setRequestHeader("Connection", "close");
AjaxRequest1.onreadystatechange = function()
{
//-----------------------------------------------
//----- RESPONSE RECEIVED FROM AJAX REQUEST -----
//-----------------------------------------------
if (this.readyState == 4) //4=Completed Ajax request
{
if (this.status == 200) //200=Call succeeded
{
if (this.responseText != null) //Check we got some response data (this.responseText or this.responseXML)
{
//----- PROCESS THE RESPONSE -----
document.getElementById('ajax_area1').innerHTML = this.responseText
}
else
{
alert("Ajax error: No data received");
}
}
else
{
alert( "Ajax error: " + this.statusText);
}
}
}
//SEND THE AJAX REQUEST
AjaxRequest1.send(AjaxRequest1Parameters); //Use (null) if there are no parameters to send
//************************************************
//************************************************
//********** CREATE AJAX REQUEST OBJECT **********
//************************************************
//************************************************
function ajaxRequest()
{
//Cross browser - deal with IE varients
try
{
//Non IE Browser
var request = new XMLHttpRequest();
}
catch(e1)
{
try
{
//IE6?
request = new ActiveXObject("Msxml2.XMLHTTP");
}
catch(e2)
{
try
{
//IE5?
request = new ActiveXObject("Microsoft.XMLHTTP");
}
catch(e3)
{
//There is no Ajax support in this browser
request = false;
}
}
}
return request;
}
</script>
</head>
<body>
<div id='ajax_area1'>THIS WILL BE REPLACED</div>
</body>
</html>
The PHP File
<?php
header('Content-Type: text/xml'); //Include these headers at the very start - they are essential to stop some browsers caching the ajax response
header("Cache-Control: no-cache, must-revalidate");
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); //A date in the past
if (isset($_POST['request_type']))
{
if ($_POST['request_type'] == "get_image_to_show")
{
//--------------------------------------------
//----- AJAX REQUEST - GET IMAGE TO SHOW -----
//--------------------------------------------
echo "WITH THIS!";
}
}
?>
Note – you can't just use "AjaxRequest1.send(AjaxRequest1Parameters);" again after first setting it up, but you can put the whole thing (including the onreadystatechange function) inside a function and call it whenever you want to send the same ajax request.
Feel free to comment if you can add help to this page or point out issues and solutions you have found. I do not provide support on this site, if you need help with a problem head over to stack overflow.