Confirm Before Leaving the Page

Following Function asks the User to Confirm if she really wants to leave the page on before unload of page.

 var myEvent = window.attachEvent || window.addEventListener;
        var chkevent = window.attachEvent ? 'onbeforeunload' : 'beforeunload'; ///for IE7, IE8
                    myEvent(chkevent, function(e) { // For >=IE7, Chrome, Firefox
                        var confirmationMessage = 'Are you sure to leave the page?';  // a space
                        (e || window.event).returnValue = confirmationMessage;
                        return confirmationMessage;
        });



This Will help to maintain data in accidental back space click. But if you click back space twice you will loose the Page.