Version: jQuery 1.4.2

Browser: Firefox 3.6.13 with Firebug 1.6.1

OS: Windows 7 Home Premium, x64

Steps to reproduce:

1. Set up a server-side handler to send the following JSON data:

{"result":"success"}

2. Perform a jQuery.ajax() call:

$.ajax({
    cache: false,
    type:  'POST',
    url:   'http://url-to-your-application',
    data:  {},
    dataType: 'json',
    error: function(e, xhr) {
        alert('error');
    }
    success: function(data, textStatus, XMLHttpRequest) {
        alert('success');
    }
});

Expected result:

An alert box with the word 'success'

Actual result:

An alert box with the word 'error'

Workaround:

The "result" property in the JSON object seems to be the problem. Changing it to "r" allows jQuery to parse the JSON correctly.