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node_modules/normalize-wheel/src/ExecutionEnvironment.js

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+/**
+ * Copyright (c) 2015, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule ExecutionEnvironment
+ */
+
+/*jslint evil: true */
+
+'use strict';
+
+var canUseDOM = !!(
+  typeof window !== 'undefined' &&
+  window.document &&
+  window.document.createElement
+);
+
+/**
+ * Simple, lightweight module assisting with the detection and context of
+ * Worker. Helps avoid circular dependencies and allows code to reason about
+ * whether or not they are in a Worker, even if they never include the main
+ * `ReactWorker` dependency.
+ */
+var ExecutionEnvironment = {
+
+  canUseDOM: canUseDOM,
+
+  canUseWorkers: typeof Worker !== 'undefined',
+
+  canUseEventListeners:
+    canUseDOM && !!(window.addEventListener || window.attachEvent),
+
+  canUseViewport: canUseDOM && !!window.screen,
+
+  isInWorker: !canUseDOM // For now, this is true - might change in the future.
+
+};
+
+module.exports = ExecutionEnvironment;