on window close give alert javascript
let disableConfirmation = false;
window.addEventListener('beforeunload', event => {
const confirmationText = 'Are you sure?';
if (!disableConfirmation) {
event.returnValue = confirmationText; // Gecko, Trident, Chrome 34+
return confirmationText; // Gecko, WebKit, Chrome <34
} else {
// Set flag back to false, just in case
// user stops loading page after clicking a link.
disableConfirmation = false;
}
});
After Confimation if you want to send any ajax request and you have used jquery
$(window).on('unload', function() {
// async: false will make the AJAX synchronous in case you're using jQuery
axios
.get('ajax_url')
.then(response => {});
});
And if no jquery is used you can use navigator, it require navigator library
navigator.sendBeacon(url, data);