Reply To: On window close run Bootstrap Popup

[Ilan Firsov]

You can’t really do this, but you can show a message to alert the user he has unsaved changes.
Add a listener for the beforeUnload event and return a string value for a message (will not show on all browsers), when the user saves the changes remove the listener – you can’t just return null or false value, you must remove the listener

A quick demo:
http://codepen.io/ilanfir/pen/Jjlky