how to find the given request from ajax with php

In my recent project ,i have to restrict a page from direct accessing from browser with typing address on browser .this page must only accessible with ajax only.thank god there is a solution to find this with php server global variable that works with php5.then i made it a simple following function.

1
2
3
4

function is_Ajax() {
return (isset($_SERVER['HTTP_X_REQUESTED_WITH']) &&
($_SERVER['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest'));
}