docs: function getOffsetParent(element) {
    if (__WEBPACK_IMPORTED_MODULE_0__utils__["a" /* default */].isWindow(element) || element.nodeType === 9) {
      return null;
    }
    // ie 这个也不是完全可行
    /*
     <div style="width: 50px;height: 100px;overflow: hidden">
     <div style="width: 50px;height: 100px;position: relative;" id="d6">
     元素 6 高 100px 宽 50px<br/>
     </div>
     </div>
     */
    // element.offsetParent does the right thing in ie7 and below. Return parent with layout!
    //  In other browsers it only includes elements with position absolute, relative or
    // fixed, not elements with overflow set to auto or scroll.
    //        if (UA.ie && ieMode < 8) {
    //            return element.offsetParent;
    //        }
    // 统一的 offsetParent 方法
    var doc = __WEBPACK_IMPORTED_MODULE_0__utils__["a" /* default */].getDocument(element);
    var body = doc.body;
    var parent = void 0;
    var positionStyle = __WEBPACK_IMPORTED_MODULE_0__utils__["a" /* default */].css(element, 'position');
    var skipStatic = positionStyle === 'fixed' || positionStyle === 'absolute';
  
    if (!skipStatic) {
      return element.nodeName.toLowerCase() === 'html' ? null : element.parentNode;
    }
  
    for (parent = element.parentNode; parent && parent !== body; parent = parent.parentNode) {
      positionStyle = __WEBPACK_IMPORTED_MODULE_0__utils__["a" /* default */].css(parent, 'position');
      if (positionStyle !== 'static') {
        return parent;
      }
    }
    return null;
  }