I'm having a hard time getting my AJAX requests to work on a staging server. It all worked fine on my development machine, but as soon as I uploaded it, all my AJAX requests stopped working. I found out that, if I change the relative urls (eg. index.php) to absolute urls (http://example.com/index.php) the requests work again, but I do not understand why.

Example request:

jQuery.post('index.php', {id: 1234, action: 1, step: 1}, function(data) { /* something */ });

This does not work, I does not even show up in the firebug console. The success handler is called though, which is very confusing.

This works just fine:

jQuery.post('http://example.com/index.php', {id: 1234, action: 1, step: 1}, function(data) { /* something */ });

Can anybody explain why AJAX requests behave in this way? x_X