title: $.getJSON get status
body: <p>Perform cross domain query, how to perform a certain function if the URL on which it is running is not available (404)?
  I try something like this:</p>
  
  <pre><code>$.getJSON({
  url:'example.php?callback=?',
  statusCode: {
  404:function(){alert('404');}
  },
  success :function(data){//do stuff}
  });
  </code></pre>