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": "unstable"

 };

 const { Ci } = require("chrome");

 const { observe } = require("../event/chrome");

 const { open } = require("../event/dom");

 const { windows } = require("../window/utils");

 const { filter, merge, map, expand } = require("../event/utils");

 // Function registers single shot event listeners for relevant window events

 // that forward events to exported event stream.

 function eventsFor(window) {

   let interactive = open(window, "DOMContentLoaded", { capture: true });

   let complete = open(window, "load", { capture: true });

   let states = merge([interactive, complete]);

   let changes = filter(states, function({target}) target === window.document);

   return map(changes, function({type, target}) {

     return { type: type, target: target.defaultView }

   });

 }

 // In addition to observing windows that are open we also observe windows

 // that are already already opened in case they're in process of loading.

 let opened = windows(null, { includePrivate: true });

 let currentEvents = merge(opened.map(eventsFor));

 // Register system event listeners for top level window open / close.

 function rename({type, target, data}) {

   return { type: rename[type], target: target, data: data }

 }

 rename.domwindowopened = "open";

 rename.domwindowclosed = "close";

 let openEvents = map(observe("domwindowopened"), rename);

 let closeEvents = map(observe("domwindowclosed"), rename);

 let futureEvents = expand(openEvents, function({target}) eventsFor(target));

 let channel = merge([currentEvents, futureEvents,

                      openEvents, closeEvents]);

 exports.events = channel;