Question

Here’s some simple Javascript:

(function($){
    var ajax_callback = function(data) { window.location.hash = data.h1; };
    $('.clickable').live('click', function() { 
             $.post('server.fcgi', {}, ajax_callback, 'json');
         }
    );
})(jQuery);

The server is a c++ binary (yes, i know) that spits out (through fast_cgi) the string:
{"h1":"newhash"}.

The expected behavior is that the URL should change.
Instead, nothing happens and Firebug complains that ‘data’ is “null”!.
Any help would be greatly appreciated!

Will.

When the following code enters “ajax_callback”, it says that “data” is “null”!.
But the server is a c++ binary that is confirmed to return the JSON string {"h1":"newhash"}.
Anyone have an idea why JQuery seems unable to accept the JSON data when calling the ajax_callback?

Answer 1

Make sure the server also returns the correct HTTP headers before the payload. E.g.:

HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: ...
...

{"h1":"bla"}

From your description, I could not quite make out if all it did was printf("{\"h1\":\"bla\"}"); or not.

To check the actual result, use a command line tool like HEAD, GET, wget, curl, or even nc. If you are not able to use one of those, you might get some clues from the Net panel in Firebug and the like.