Detect an AJAX Request in PHP

Whenever you need to check if request is Ajax or non-Ajax, you can check it using following code.

if(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') {
echo "This is an Ajax Request";
}else {
echo "Not an Ajax Request";
}

Reference : http://davidwalsh.name/detect-ajax