How to display a message when closing a bookmark in JavaScript?

Question

JavaScript

Hello, I want to make it so that when you close the browser window with our site or something else, when you leave our site, display a message
How to do this?

Answer 1

window.onbeforeunload = function () {
  return "Точно хочешь закрыть страницу?";
}

But:
1) Such sites are infuriating
2) In different browsers, the message will look different, browsers also add their own additional text, stating that the message is displayed by the site, and not by the browser.

Answer 2

You can display the table using onbeforeunload
Example
Doesn't work everywhere. And almost none of the modern browsers allows you to change the message.