The Tor Browser / file revision

 /* 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/. */

 "use strict";

 module.metadata = {

   "stability": "experimental"

 };

 const method = require("../../method/core");

 const { Class } = require("./heritage");

 // Object that inherit or mix WeakRefence inn will register

 // weak observes for system notifications.

 const WeakReference = Class({});

 exports.WeakReference = WeakReference;

 // If `isWeak(object)` is `true` observer installed

 // for such `object` will be weak, meaning that it will

 // be GC-ed if nothing else but observer is observing it.

 // By default everything except `WeakReference` will return

 // `false`.

 const isWeak = method("reference/weak?");

 exports.isWeak = isWeak;

 isWeak.define(Object, _ => false);

 isWeak.define(WeakReference, _ => true);