Alert on Browser Back button click or page refresh
<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>