event.js

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Copyright 2005 Google Inc. All Rights Reserved.

/**
 * @fileoverview A base class for event objects.
 *
 */


goog.provide('goog.events.Event');

goog.require('goog.Disposable');


/**
 * A base class for event objects, so that they can support preventDefault and
 * stopPropagation.
 *
 * @param {string} type Event Type.
 * @param {Object} opt_target Reference to the object that is the target of this
 *     event.
 * @constructor
 * @extends {goog.Disposable}
 */
goog.events.Event = function(type, opt_target) {
  goog.Disposable.call(this);

  /**
   * Event type.
   * @type {string}
   */
  this.type = type;

  /**
   * Target of the event.
   * @type {Object|undefined}
   */
  this.target = opt_target;

  /**
   * Object that had the listener attached.
   * @type {Object|undefined}
   */
  this.currentTarget = this.target;
};
goog.inherits(goog.events.Event, goog.Disposable);


/** @inheritDoc */
goog.events.Event.prototype.disposeInternal = function() {
  delete this.type;
  delete this.target;
  delete this.currentTarget;
};


/**
 * Whether to cancel the event in internal capture/bubble processing for IE.
 * @type {boolean}
 * @private
 */
goog.events.Event.prototype.propagationStopped_ = false;


/**
 * Return value for in internal capture/bubble processing for IE.
 * @type {boolean}
 * @private
 */
goog.events.Event.prototype.returnValue_ = true;


/**
 * Stops event propagation.
 */
goog.events.Event.prototype.stopPropagation = function() {
  this.propagationStopped_ = true;
};


/**
 * Prevents the default action, for example a link redirecting to a url.
 */
goog.events.Event.prototype.preventDefault = function() {
  this.returnValue_ = false;
};