JSFiddle - React, Tailwind, and code Playground

by Apostle

HTML

<a href="jsfiddle.net">jsfiddle</a>

JavaScript

/*
The different results on the JavaScript event onBeforeUnload:
FireFox - a confirm message with text about a possible loss of unsaved changed data;
Google Chrome - a confirm message with text 'My warning!';
Opera - nothing (none of this event handler, but available like - onUnload).
*/
window.onbeforeunload = function(e) {
    return 'My warning!';
};