Ajax for PHP Developers

Read The Full Tutorial.

In this article we will create a simple php tutorials, and how can we use AJAX with PHP.

1. Create an XMLHttpRequest object

The following codes creates an XMLHttpRequest for all browsers:

var req;

if(window.XMLHttpRequest){
//For Firefox, Safari, Opera
req = new XMLHttpRequest();
}
else if(window.ActiveXObject){
//For IE 5
req = new ActiveXObject("Microsoft.XMLHTTP");
} else if(window.ActiveXObject){
//For IE 6+
req = new ActiveXObject("Msxml2.XMLHTTP");
}
else{
//Error for an old browser
alert('Your browser is not IE 5 or higher, or Firefox or Safari or Opera');
}

Here, first we are using the built-in JavaScript function XMLHttpRequest() for creating an XMLHttpRequest for Firefox, Safari and Opera. If the browser does support window.ActiveXObject, then it is Internet Explorer. For IE versions 5.0+, use new ActiveXObject("Microsoft.XMLHTTP") and for IE 6.0+ use new ActiveXObject("Msxml2.XMLHTTP"). If the browser does not support the built-in JavaScript function XMLHttpRequest() or ActiveXObject, then it does not support AJAX. You can also use JavaScript try-catch blocks for the same output.

var req;
try
{
// Firefox, Opera, Safari
xmlHttp=new XMLHttpRequest();
}
catch (e)
{
// Internet Explorer
try
{
xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e)
{
try
{
xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e)
{
alert('Your browser is not IE 5 or higher, or Firefox or Safari or Opera');
}
}
}

2. Request for a web page

After creating the XMLHttpRequest we now need to send a request for a web page

req.open(“GET”,”somedata.php”);
req.send(null);

3. Monitor for the response of the request

You now need to monitor for the state of the request.you can do by this code

req.onreadystatechange=function()
{
if(req.readyState==4 && req.status == 200)
{
var resp = req.responseText;
}
}