title: event object not defined only with Firefox (IE and Chrome works)
body: <pre><code>&lt;a class="lnk" href="#" onclick="showItem();"&gt;
      &lt;span data-id="27"&gt;TEST&lt;/span&gt;
  &lt;/a&gt;
  
  function showItem()
  {
      var itid = event.target.dataset.id;
      alert(itid);
  }
  </code></pre>
  
  <p>If you try <a href="http://jsfiddle.net/tek5yqdd/1/" rel="nofollow">this jsfiddle code</a> you can see that with IE (11) and Chrome the event object is correctly evaluated, but with Firefox (32.0) you get an error (ReferenceError : event is not defined)</p>
  
  <p>It's a bug of Firefox or a different event object lifecycle in IE and Chrome ?
  However since in IE and Chrome it's working I think it's a problem.
  About a workaround ?</p>
  
  <p>p.s: in jsfiddle, only with firefox, code selection still having problem (after some run you cannot select code.</p>