title: beforeSend in $.getJSON
body: <p>How do I use <code>beforeSend</code> callback in <code>$.getJSON</code>(cross domain).   </p>
  
  <p>More specifically <code>$.getJSON</code> is call is to a YQL service 
  Like </p>
  
  <blockquote>
    <p>select * from html where
    url=”<a href="http://www.yahoo.com" rel="noreferrer">http://www.yahoo.com</a>”</p>
  </blockquote>