gecko-dev/dom/webidl/BeforeUnloadEvent.webidl

/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * For more information on this interface, please see
 * http://www.whatwg.org/specs/web-apps/current-work/#beforeunloadevent
 */

[Exposed=Window]
interface BeforeUnloadEvent : Event {
  attribute DOMString returnValue;
};