1 files changed, 68 insertions, 0 deletions
diff --git a/toolkit/jetpack/sdk/window/events.js b/toolkit/jetpack/sdk/window/events.js
new file mode 100644
index 000000000..b1d3a1f3e
--- /dev/null
+++ b/toolkit/jetpack/sdk/window/events.js
@@ -0,0 +1,68 @@
+/* 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, Cu } = 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 documentMatches(weakWindow, event) {
+  let window = weakWindow.get();
+  return window && event.target === window.document;
+}
+
+function makeStrictDocumentFilter(window) {
+  // Note: Do not define a closure within this function.  Otherwise
+  //       you may leak the window argument.
+  let weak = Cu.getWeakReference(window);
+  return documentMatches.bind(null, weak);
+}
+
+function toEventWithDefaultViewTarget({type, target}) {
+  return { type: type, target: target.defaultView }
+}
+
+// Function registers single shot event listeners for relevant window events
+// that forward events to exported event stream.
+function eventsFor(window) {
+  // NOTE: Do no use pass a closure from this function into a stream
+  //       transform function.  You will capture the window in the
+  //       closure and leak the window until the event stream is
+  //       completely closed.
+  let interactive = open(window, "DOMContentLoaded", { capture: true });
+  let complete = open(window, "load", { capture: true });
+  let states = merge([interactive, complete]);
+  let changes = filter(states, makeStrictDocumentFilter(window));
+  return map(changes, toEventWithDefaultViewTarget);
+}
+
+// Create our event channels.  We do this in a separate function to
+// minimize the chance of leaking intermediate objects on the global.
+function makeEvents() {
+  // 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.
+  var opened = windows(null, { includePrivate: true });
+  var 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";
+
+  var openEvents = map(observe("domwindowopened"), rename);
+  var closeEvents = map(observe("domwindowclosed"), rename);
+  var futureEvents = expand(openEvents, ({target}) => eventsFor(target));
+
+  return merge([currentEvents, futureEvents, openEvents, closeEvents]);
+}
+
+exports.events = makeEvents();