title: Alert on Browser Back button click or page refresh
body: <p>I have seen the same function is multiple sites including SO. I am also trying to achieve this.
  Here is the code so far. </p>
  
  <pre><code> &lt;script&gt;
              var myEvent = window.attachEvent || window.addEventListener;
              var chkevent = window.attachEvent ? 'onbeforeunload' : 'beforeunload'; 
  
              myEvent(chkevent, function(e) { // For &gt;=IE7, Chrome, Firefox
                  var confirmationMessage = ' ';  
                  (e || window.event).returnValue = confirmationMessage;
                  return confirmationMessage;
              });
          &lt;/script&gt;
  </code></pre>
  
  <p>The problem is above code is working fine in chrome and IE but when I tried to test in on Firefox it is not working. I checked firebug but there is no error.
  I updated the firefox and version are 47.0.1.</p>
  
  <p>But issue not fixed. </p>
  
  <p>Any advice would be helpful. </p>
  
  <p>Guys if you have code better than this then it would be also helpful.</p>