title: Cancel/Abort/Confirm an HTML 5 state change event (onpopstate)
body: <p>With unload event of window, it is possible to show the user a confirmation dialog , let's say in a situation where there is an ongoing request you are waiting for to finish and navigating away from the page will terminate that request.</p>
  
  <p>Is there a way to accomplish this with onpopstate of HTML5 history API? Or any other way with the same outcome?</p>