ui/webui/resources/cr_elements/v1_0/cr_events/cr_events.js

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * @fileoverview
   7  * `cr-events` provides helpers for handling events in Chrome Polymer elements.
   8  *
   9  * Example:
  10  *
  11  *    <cr-events id="events"></cr-events>
  12  *
  13  * Usage:
  14  *
  15  *    this.$.events.forward(this.$.element, ['change']);
  16  *
  17  * @element cr-events
  18  */
  19 Polymer({
  20   is: 'cr-events',
  21
  22   /**
  23    * Sets up an element to forward events across the shadow boundary, for events
  24    * which normally stop at the root node (see http://goo.gl/WGMO9x).
  25    * @param {!HTMLElement} element The element to forward events from.
  26    * @param {!Array<string>} events The events to forward.
  27    */
  28   forward: function(element, events) {
  29     for (var i = 0; i < events.length; i++)
  30       element.addEventListener(events[i], this.forwardEvent_);
  31   },
  32
  33   /**
  34    * Forwards events that don't automatically cross the shadow boundary
  35    * if the event should bubble.
  36    * @param {!Event} e The event to forward.
  37    * @param {*} detail Data passed when initializing the event.
  38    * @param {Node=} opt_sender Node that declared the handler.
  39    * @private
  40    */
  41   forwardEvent_: function(e, detail, opt_sender) {
  42     if (!e.bubbles)
  43       return;
  44
  45     var node = e.path[e.path.length - 1];
  46     if (node instanceof ShadowRoot) {
  47       // Forward the event to the shadow host.
  48       e.stopPropagation();
  49       node.host.fire(e.type, detail, node.host, true, e.cancelable);
  50     }
  51   },
  52 });