To Logoff, Restart or Shutdown Windows using Batch you can Simply execute shutdown with the needed parameters. To execute the shutdown command you need the sufficient user privileges.
List of Parameters
prompt
How to make a confirmation prompt before leaving the page in javascript
To make a confirmation prompt before leaving the page in javascript you can use the following snippet.
Sample Javascript
window.onbeforeunload = function(){
var msg = 'Do you really want to leave this page?';
return msg;
};