Is it possible to display a custom message in the beforeunload popup?

Question

When using window.onbeforeunload (or $(window).on(\"beforeonload\")), is it possible to display a custom message in that popup?

Maybe a sma

Answer 1

I just made a div appear that shows a message in the background. It is behind the modal but this is better then nothing. It is kind of shady but at least you can give your user some info on why you bother her/him not to leave.

constructor($elem)
{
    $(window).unbind().bind('beforeunload', (e) => this.beforeUnload(e));
}
beforeUnload(e)
{
    $('#leaveWarning').show();
    setTimeout(function(){
        $('#leaveWarning').hide();
    }, 1); // set this to 1ms .. since timers are stopped for this modal,
           // the message will disappear right after the user clicked one of the options  
    return "This message is not relevant in most modern browsers.";
}

Here is a working Fiddle https://jsfiddle.net/sy3fda05/2/