text: /**
   * Copyright (c) Facebook, Inc. and its affiliates.
   *
   * This source code is licensed under the MIT license found in the
   * LICENSE file in the root directory of this source tree.
   *
   * @flow
   */
  
  /**
   * Translation from modifier key to the associated property in the event.
   * @see http://www.w3.org/TR/DOM-Level-3-Events/#keys-Modifiers
   */
  
  import type {AnyNativeEvent} from 'events/PluginModuleType';
  
  const modifierKeyToProp = {
    Alt: 'altKey',
    Control: 'ctrlKey',
    Meta: 'metaKey',
    Shift: 'shiftKey',
  };
  
  // IE8 does not implement getModifierState so we simply map it to the only
  // modifier keys exposed by the event itself, does not support Lock-keys.
  // Currently, all major browsers except Chrome seems to support Lock-keys.
  function modifierStateGetter(keyArg: string): boolean {
    const syntheticEvent = this;
    const nativeEvent = syntheticEvent.nativeEvent;
    if (nativeEvent.getModifierState) {
      return nativeEvent.getModifierState(keyArg);
    }
    const keyProp = modifierKeyToProp[keyArg];
    return keyProp ? !!nativeEvent[keyProp] : false;
  }
  
  function getEventModifierState(
    nativeEvent: AnyNativeEvent,
  ): (keyArg: string) => boolean {
    return modifierStateGetter;
  }
  
  export default getEventModifierState;
  