<!DOCTYPE html>
<html>
<body onbeforeunload="return myFunction()">
<p>Close this window, press F5 or click on the link below to invoke the onbeforeunload event.</p>
<a href="https://horje.com">Click here to go to horje.com</a>
<script>
function myFunction() {
return "Write something clever here...";
}
</script>
</body>
</html>