docs: function fastCheck() {
          for (var i = watchArray.length - 1; i >= 0; i--) {
              if (!watchArray[i].inited) continue;
  
              var deltaTop = Math.abs(getDocOffsetTop(watchArray[i].clone) - watchArray[i].docOffsetTop),
                  deltaHeight = Math.abs(watchArray[i].parent.node.offsetHeight - watchArray[i].parent.height);
  
              if (deltaTop >= 2 || deltaHeight >= 2) return false;
          }
          return true;
      }