3 Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
4 This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
5 The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
6 The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
7 Code distributed by Google as part of the polymer project is also
8 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
10 <link rel=
"import" href=
"../polymer/polymer.html">
15 `iron-signals` provides basic publish-subscribe functionality.
17 Note: avoid using `iron-signals` whenever you can use
18 a controller (parent element) to mediate communication
21 To send a signal, fire a custom event of type `iron-signal`, with
22 a detail object containing `name` and `data` fields.
24 this.fire('iron-signal', {name: 'hello', data: null});
26 To receive a signal, listen for `iron-signal-<name>` event on a
27 `iron-signals` element.
29 <iron-signals on-iron-signal-hello="{{helloSignal}}">
31 You can fire a signal event from anywhere, and all
32 `iron-signals` elements will receive the event, regardless
33 of where they are in DOM.
40 attached: function() {
43 detached: function() {
44 var i
= signals
.indexOf(this);
51 // private shared database
55 function notify(name
, data
) {
56 // convert generic-signal event to named-signal event
57 var signal
= new CustomEvent('iron-signal-' + name
, {
58 // if signals bubble, it's easy to get confusing duplicates
59 // (1) listen on a container on behalf of local child
60 // (2) some deep child ignores the event and it bubbles
61 // up to said container
62 // (3) local child event bubbles up to container
63 // also, for performance, we avoid signals flying up the
64 // tree from all over the place
68 // dispatch named-signal to all 'signals' instances,
69 // only interested listeners will react
70 signals
.forEach(function(s
) {
71 s
.dispatchEvent(signal
);
75 // signal listener at document
76 document
.addEventListener('iron-signal', function(e
) {
77 notify(e
.detail
.name
, e
.detail
.data
);