var getPageScroll = (window.pageXOffset !== undefined) ?
  function () {
    return {
      top: pageYOffset,
      left: pageXOffset
    }
  } : function () {
    var html = document.documentElement;
    var body = document.body;

    var top = html.scrollTop || body && body.scrollTop || 0;
    top -= html.clientTop; // only for IE7

    var left = html.scrollLeft || body && body.scrollLeft || 0;
    left -= html.clientLeft; // only for IE7

    return {
      top: top,
      left: left
    }
  };