I've created this simple JavaScript function which I've added to an external Javascript file and now call from server-side code on most every page:

    function ToggleBeforeUnload(onOff)
    {
      if (onOff == true)
        window.onbeforeunload = UnloadPage;
      else
      {
        window.onbeforeunload = null;
      }
    }

It *appears* that when onOff = false the latter statement is having no effect.  In other words, by calling "window.onbeforeunload = null" what I want to do is NOT have it call "UnloadPage" anymore.

Is it possible that I'm using the wrong approach and there's another way to disable the "onbeforeunload" event?

Robert

hi,

please change the code as follows.

 if (window.addEventListener) {
                    window.addEventListener("onbeforeunload", Unloadpage, false);
                } else if (window.attachEvent) {
                    window.attachEvent("onbeforeunload", Unloadpage);
                } else {
                    window.onbeforeunload= Unloadpage;
                }

try this,it will work

That worked for me. How are you setting your "onOff" variable? Here is what I tried:

<form id="Form1" method="post" runat="server">
 <input type="button" onclick="window.onbeforeunload = null;" value="Turn it off">
</form>

<script type="text/javascript">
<!--
function windowOnBeforeUnload()
{
 return 'Are you sure?';
}

window.onbeforeunload = windowOnBeforeUnload;
// -->
</script>

NC...

NC,

That's the way I used to have things considered but since then I've built a much more sophisticated mechanism that automatically saves all specially marked Session variables to a special table in the DB.  It then restores them the next time the user logs in.  It's done with serialization.  It works really well but does require that JavaScript function to call the UnloadPage javascript function.

Sathesh,

Thank you for your code but I don't understand it.  Could you explain to me where in your code you are disabling the call to UnloadPage?  Put another way, once I've setup 'window.onbeforeunload' to call UnloadPage, how do I disable this?  I know how to do it in C# with server-side event handlers but I simply want to learn how to do it with JavaScript.

Robert

How about something as simple as: 

var isEnabled = true;
window.onbeforeunload = function (e) {
  if(isEnabled){
    var e = e || window.event;

    if (e) {
      e.returnValue = 'Any string';
    }
    else{
      return 'Any string';
    }
  }
}

Eric

 Did you try the code or just look at it?

Run the code the way it is....than run the code with the boolean set to false.

Eric

rmdw:

NC,

That's the way I used to have things considered but since then I've built a much more sophisticated mechanism that automatically saves all specially marked Session variables to a special table in the DB.  It then restores them the next time the user logs in.  It's done with serialization.  It works really well but does require that JavaScript function to call the UnloadPage javascript function.

Sathesh,

Thank you for your code but I don't understand it.  Could you explain to me where in your code you are disabling the call to UnloadPage?  Put another way, once I've setup 'window.onbeforeunload' to call UnloadPage, how do I disable this?  I know how to do it in C# with server-side event handlers but I simply want to learn how to do it with JavaScript.

 

Robert

The code is simple enough. When you press the button, the onbeforeunload is set to null, and won't be called if you "X" close the page. Otherwise it will.

NC...