JSFiddle - React, Tailwind, and code Playground

by Felis Catus

JavaScript

window.addEventListener("beforeunload", function (event) {
  // Cancel the event as stated by the standard.
  document.querySelector('body').setAttribute('style', 'background: red;');
  event.preventDefault();
  
  // Chrome requires returnValue to be set.
  event.returnValue = 'Delete operation in progress; navigating away will result in some entities not being deleted';
  return "please nooooo";
});