docs: function (vnode, options) {
      const scroller = getParentScroller(vnode)
      const scrollDirection = scroller.scrollDirection || 'vertical'
  
      if (scroller && scroller.$el && vnode.$el) {
        // if it's a list, then the listVnode.scrollDirection is undefined. just
        // assum it is the default value 'vertical'.
        const dSuffix = ({
          horizontal: 'Left',
          vertical: 'Top'
        })[scrollDirection]
        let offset = vnode.$el[`offset${dSuffix}`]
  
        if (options) {
          offset += Number(options.offset) || 0
          offset *= jud.config.env.scale /* adapt offset to different screen scales. */
        }
        else if (process.env.NODE_ENV === 'development') {
          console.warn('[Vue Render] The second parameter of "scrollToElement" is required, '
            + 'otherwise it may not works well on native.')
        }
  
        step({
          scrollable: scroller.$el,
          startTime: now(),
          frame: null,
          startPosition: scroller.$el[`scroll${dSuffix}`],
          position: offset,
          method: scrollElement,
          dSuffix: dSuffix
        })
      }
    }