1// https://developer.mozilla.org/en-US/docs/Web/API/PageTransitionEvent
2window.addEventListener('pageshow', myFunction);
3
4function myFunction(event) { 
5  if (event.persisted) {
6    alert("The page was cached by the browser");
7  } else {
8    alert("The page was NOT cached by the browser");
9  }
10}