title: How to make all AJAX calls sequential?
body: <p>I use jQuery. And I don't want parallel AJAX calls on my application, each call must wait the previous before starting. How to implement it? There is any helper?</p>
  
  <p><strong>UPDATE</strong> If there is any synchronous version of the XMLHttpRequest or jQuery.post I would like to know. But sequential != synchronous, and I would like an asynchronous and sequential solution.</p>