text: "use strict";
  
  /**
   * Copyright (c) 2013-present, 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.
   *
   */
  
  /**
   * @param {DOMElement} element
   * @param {DOMDocument} doc
   * @return {boolean}
   */
  function _isViewportScrollElement(element, doc) {
    return !!doc && (element === doc.documentElement || element === doc.body);
  }
  
  /**
   * Scroll Module. This class contains 4 simple static functions
   * to be used to access Element.scrollTop/scrollLeft properties.
   * To solve the inconsistencies between browsers when either
   * document.body or document.documentElement is supplied,
   * below logic will be used to alleviate the issue:
   *
   * 1. If 'element' is either 'document.body' or 'document.documentElement,
   *    get whichever element's 'scroll{Top,Left}' is larger.
   * 2. If 'element' is either 'document.body' or 'document.documentElement',
   *    set the 'scroll{Top,Left}' on both elements.
   */
  
  var Scroll = {
    /**
     * @param {DOMElement} element
     * @return {number}
     */
    getTop: function (element) {
      var doc = element.ownerDocument;
      return _isViewportScrollElement(element, doc) ?
      // In practice, they will either both have the same value,
      // or one will be zero and the other will be the scroll position
      // of the viewport. So we can use `X || Y` instead of `Math.max(X, Y)`
      doc.body.scrollTop || doc.documentElement.scrollTop : element.scrollTop;
    },
  
    /**
     * @param {DOMElement} element
     * @param {number} newTop
     */
    setTop: function (element, newTop) {
      var doc = element.ownerDocument;
      if (_isViewportScrollElement(element, doc)) {
        doc.body.scrollTop = doc.documentElement.scrollTop = newTop;
      } else {
        element.scrollTop = newTop;
      }
    },
  
    /**
     * @param {DOMElement} element
     * @return {number}
     */
    getLeft: function (element) {
      var doc = element.ownerDocument;
      return _isViewportScrollElement(element, doc) ? doc.body.scrollLeft || doc.documentElement.scrollLeft : element.scrollLeft;
    },
  
    /**
     * @param {DOMElement} element
     * @param {number} newLeft
     */
    setLeft: function (element, newLeft) {
      var doc = element.ownerDocument;
      if (_isViewportScrollElement(element, doc)) {
        doc.body.scrollLeft = doc.documentElement.scrollLeft = newLeft;
      } else {
        element.scrollLeft = newLeft;
      }
    }
  };
  
  module.exports = Scroll;