fix bugs in page

docs/js/goog/events/browserfeature.js

@@ -0,0 +1,122 @@
+// Copyright 2010 The Closure Library Authors. All Rights Reserved.
+//
+// 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.
+
+/**
+ * @fileoverview Browser capability checks for the events package.
+ *
+ */
+
+
+goog.provide('goog.events.BrowserFeature');
+
+goog.require('goog.userAgent');
+goog.scope(function() {
+
+
+
+/**
+ * Enum of browser capabilities.
+ * @enum {boolean}
+ */
+goog.events.BrowserFeature = {
+  /**
+   * Whether the button attribute of the event is W3C compliant.  False in
+   * Internet Explorer prior to version 9; document-version dependent.
+   */
+  HAS_W3C_BUTTON:
+      !goog.userAgent.IE || goog.userAgent.isDocumentModeOrHigher(9),
+
+  /**
+   * Whether the browser supports full W3C event model.
+   */
+  HAS_W3C_EVENT_SUPPORT:
+      !goog.userAgent.IE || goog.userAgent.isDocumentModeOrHigher(9),
+
+  /**
+   * To prevent default in IE7-8 for certain keydown events we need set the
+   * keyCode to -1.
+   */
+  SET_KEY_CODE_TO_PREVENT_DEFAULT:
+      goog.userAgent.IE && !goog.userAgent.isVersionOrHigher('9'),
+
+  /**
+   * Whether the {@code navigator.onLine} property is supported.
+   */
+  HAS_NAVIGATOR_ONLINE_PROPERTY:
+      !goog.userAgent.WEBKIT || goog.userAgent.isVersionOrHigher('528'),
+
+  /**
+   * Whether HTML5 network online/offline events are supported.
+   */
+  HAS_HTML5_NETWORK_EVENT_SUPPORT:
+      goog.userAgent.GECKO && goog.userAgent.isVersionOrHigher('1.9b') ||
+      goog.userAgent.IE && goog.userAgent.isVersionOrHigher('8') ||
+      goog.userAgent.OPERA && goog.userAgent.isVersionOrHigher('9.5') ||
+      goog.userAgent.WEBKIT && goog.userAgent.isVersionOrHigher('528'),
+
+  /**
+   * Whether HTML5 network events fire on document.body, or otherwise the
+   * window.
+   */
+  HTML5_NETWORK_EVENTS_FIRE_ON_BODY:
+      goog.userAgent.GECKO && !goog.userAgent.isVersionOrHigher('8') ||
+      goog.userAgent.IE && !goog.userAgent.isVersionOrHigher('9'),
+
+  /**
+   * Whether touch is enabled in the browser.
+   */
+  TOUCH_ENABLED:
+      ('ontouchstart' in goog.global ||
+       !!(goog.global['document'] && document.documentElement &&
+          'ontouchstart' in document.documentElement) ||
+       // IE10 uses non-standard touch events, so it has a different check.
+       !!(goog.global['navigator'] &&
+          goog.global['navigator']['msMaxTouchPoints'])),
+
+  /**
+   * Whether addEventListener supports {passive: true}.
+   * https://developers.google.com/web/updates/2016/06/passive-event-listeners
+   */
+  PASSIVE_EVENTS: purify(function() {
+    // If we're in a web worker or other custom environment, we can't tell.
+    if (!goog.global.addEventListener || !Object.defineProperty) {  // IE 8
+      return false;
+    }
+
+    var passive = false;
+    var options = Object.defineProperty({}, 'passive', {
+      get: function() {
+        passive = true;
+      }
+    });
+    goog.global.addEventListener('test', goog.nullFunction, options);
+    goog.global.removeEventListener('test', goog.nullFunction, options);
+
+    return passive;
+  })
+};
+
+
+/**
+ * Tricks Closure Compiler into believing that a function is pure.  The compiler
+ * assumes that any `valueOf` function is pure, without analyzing its contents.
+ *
+ * @param {function(): T} fn
+ * @return {T}
+ * @template T
+ */
+function purify(fn) {
+  return ({valueOf: fn}).valueOf();
+}
+});  // goog.scope