title: how to determine failure in ajax request
body: <p>I'm working with Mootools to develop a simple ajax-y page that does some manipulation with db records using PHP as the backend. </p>
  
  <p>I'm submitting the ajax request to a PHP page that calls a function and returns <code>TRUE</code> or <code>FALSE</code> if the record was able to be updated/deleted or not.</p>
  
  <p>However, it seems like the mootools <code>onSuccess</code> event is fired anytime the server returns a 200 status, regardless of the value returned (eg. <code>FALSE</code> is still assumed to be a success).</p>
  
  <p>How do I use onSuccess in a meaningful way, short of returning a 40x error code or something?</p>