$.ajax crossdomain error handling

HTML

<p><a href="#" class="right">Get correct ajax script</a></p>
<p><a href="#" class="wrong">Get incorrect ajax script</a></p>

JavaScript

$('a.right').click(function() {
 runAjax('http://cdnjs.cloudflare.com/ajax/libs/backbone.js/0.9.2/backbone-min.js');
});

$('a.wrong').click(function() {
 runAjax('http://cdnjs.cloudflare.com/ajax/libs/backbone.js/0.9.2/fake-min.js');
});

function runAjax(urlVar) {
  $.ajax({
    type: "GET", url: urlVar, dataType: 'script',
    timeout : 5000,
    success: function(data) {
        alert('it worked');
    },
    error: function(xhr, ajaxOptions, thrownError) {
        alert('it did not work');
    },
  });
}