# lib/goog/events/browserfeature.js

    1// Copyright 2010 The Closure Library Authors. All Rights Reserved.2//3// Licensed under the Apache License, Version 2.0 (the "License");4// you may not use this file except in compliance with the License.5// You may obtain a copy of the License at6//7//      http://www.apache.org/licenses/LICENSE-2.08//9// Unless required by applicable law or agreed to in writing, software10// distributed under the License is distributed on an "AS-IS" BASIS,11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.12// See the License for the specific language governing permissions and13// limitations under the License.1415/**16 * @fileoverview Browser capability checks for the events package.17 *18 */192021goog.provide('goog.events.BrowserFeature');2223goog.require('goog.userAgent');242526/**27 * Enum of browser capabilities.28 * @enum {boolean}29 */30goog.events.BrowserFeature = {31  /**32   * Whether the button attribute of the event is W3C compliant.  False in33   * Internet Explorer prior to version 9; document-version dependent.34   */35  HAS_W3C_BUTTON: !goog.userAgent.IE ||36      goog.userAgent.isDocumentModeOrHigher(9),3738  /**39   * Whether the browser supports full W3C event model.40   */41  HAS_W3C_EVENT_SUPPORT: !goog.userAgent.IE ||42      goog.userAgent.isDocumentModeOrHigher(9),4344  /**45   * To prevent default in IE7-8 for certain keydown events we need set the46   * keyCode to -1.47   */48  SET_KEY_CODE_TO_PREVENT_DEFAULT: goog.userAgent.IE &&49      !goog.userAgent.isVersionOrHigher('9'),5051  /**52   * Whether the {@code navigator.onLine} property is supported.53   */54  HAS_NAVIGATOR_ONLINE_PROPERTY: !goog.userAgent.WEBKIT ||55      goog.userAgent.isVersionOrHigher('528'),5657  /**58   * Whether HTML5 network online/offline events are supported.59   */60  HAS_HTML5_NETWORK_EVENT_SUPPORT:61      goog.userAgent.GECKO && goog.userAgent.isVersionOrHigher('1.9b') ||62      goog.userAgent.IE && goog.userAgent.isVersionOrHigher('8') ||63      goog.userAgent.OPERA && goog.userAgent.isVersionOrHigher('9.5') ||64      goog.userAgent.WEBKIT && goog.userAgent.isVersionOrHigher('528'),6566  /**67   * Whether HTML5 network events fire on document.body, or otherwise the68   * window.69   */70  HTML5_NETWORK_EVENTS_FIRE_ON_BODY:71      goog.userAgent.GECKO && !goog.userAgent.isVersionOrHigher('8') ||72      goog.userAgent.IE && !goog.userAgent.isVersionOrHigher('9'),7374  /**75   * Whether touch is enabled in the browser.76   */77  TOUCH_ENABLED:78      ('ontouchstart' in goog.global ||79          !!(goog.global['document'] &&80             document.documentElement &&81             'ontouchstart' in document.documentElement) ||82          // IE10 uses non-standard touch events, so it has a different check.83          !!(goog.global['navigator'] &&84              goog.global['navigator']['msMaxTouchPoints']))85};