Cross-domain ajax request

Normally, if you send an ajax request to a server script stays in a different domain server, you will get this error:

XMLHttpRequest cannot load http://my.external.domain/myscript.php. Origin http://my.external.domain is not allowed by Access-Control-Allow-Origin.

So, to allow other domains call this cript, just set the 'access-control-allow-origin' header equal '*'.

For example:

http://my.external.domain/myscript.php

<?php header('content-type: application/json; charset=utf-8');
header('access-control-allow-origin: *');

$date = date('m-d-Y h:i:s a', time());

$json = json_encode($date);

echo isset($_GET['callback'])
    ? "{$_GET['callback']}($json)"
    : $json;
?>

And in my current site, send the ajax request to myscript.php:

var mydate = '';

jQuery.ajax({ url: 'http://my.external.domain/myscript.php', crossDomain: true, type: 'GET' }).done(function(res){ console.log(res); mydate = res; });

References:

http://www.geekality.net/2010/06/27/php-how-to-easily-provide-json-and-jsonp/