api-console-assets/bower_components/events-target-behavior/events-target-behavior.html

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<link rel="import" href="../polymer/polymer.html">

<script>
(function() {
'use strict';

window.ArcBehaviors = window.ArcBehaviors || {};
/**
 * A `ArcBehaviors.EventsTargetBehavior` is a base behavior that allows setting
 * up event listeners on a default or set node.
 *
 * By default the element listens on the `window` element for events. By setting
 * `eventsTarget` property of this element it removes all previously set
 * listeners and adds the same listeners to the node.
 * It also restores default state when the `eventsTarget` is removed.
 *
 * Implementations should implement two abstract methods:
 * `_attachListeners(node)` and `_detachListeners(node)`. Both of them will be
 * called with event target argument when it's required to either set or remove
 * listeners.
 *
 * ### Example (Polymer 1.x)
 *
 * ```javascript
 * Polymer({
 *   is: 'my-element',
 *   behaviors: [ArcBehaviors.EventsTargetBehavior],
 *   _attachListeners: function(node) {
 *     this.listen(node, 'event-type', 'handlerName');
 *   },
 *   _detachListeners: function(node) {
 *     this.unlisten(node, 'event-type', 'handlerName');
 *   }
 * });
 * ```
 *
 * The behavior handles attached / detached state and calls the functions with
 * required parameters.
 *
 * @polymerBehavior ArcBehaviors.EventsTargetBehavior
 * @group Logic Elements
 */
window.ArcBehaviors.EventsTargetBehavior = {

  properties: {
    /**
     * Events handlers target. By default the element listens on
     * `window` object. If set, all events listeners will be attached to this
     * object instead of `window`.
     */
    eventsTarget: {
      type: Object,
      observer: '_eventsTargetChanged'
    },
    // An event target used to attach listeners.
    _oldEventsTarget: Object
  },

  attached: function() {
    this._eventsTargetChanged(this.eventsTarget);
  },

  detached: function() {
    if (this._oldEventsTarget) {
      this._detachListeners(this._oldEventsTarget);
    }
  },
  /**
   * Removes old handlers (if any) and attaches listeners on new event
   * event target.
   *
   * @param {?Node} eventsTarget Event target to set handlers on. If not set it
   * will set handlers on the `window` object.
   */
  _eventsTargetChanged: function(eventsTarget) {
    if (this._oldEventsTarget) {
      this._detachListeners(this._oldEventsTarget);
    }
    this._oldEventsTarget = eventsTarget || window;
    this._attachListeners(this._oldEventsTarget);
  },
  // To be implement by the element to set event listeners on the target
  _attachListeners: function() {
    console.warn('_attachListeners not found in the element methods');
  },
  // To be implement by the element to remove event listeners from the target
  _detachListeners: function() {
    console.warn('_detachListeners not found in the element methods');
  }
};
})();
</script>