Open a Modal when closing browser tab

Question

Want to open a modal when closing browser tab. Tried window.onbeforeunload , window.unload but not working. Any Other Solution with JavaScript or jQuery?

    <script>
        window.onbeforeunload = modal;

        function modal() {
        return 'leaving';
        }
    </script>

Answer 1

I think it's forbidden.In modern browsers, any action want to stop closing window is impossible.

some actions such as window.showModalDialog(), window.alert(), window.confirm(),window.prompt() are ignored in onunload or onbeforeunload event.

And, if u can do these actions, means you can make the browser can't be closed. it's dangerous for users