this.update = function(bKeepScroll){
      var bKeepScroll = bKeepScroll || false;
      var CurrentScroll = iScroll;
      iScroll = 0;      
      oViewport[options.axis] = oViewport.obj[0]['offset'+ sSize];
      oContent[options.axis] = oContent.obj[0]['scroll'+ sSize];
      oContent.ratio = oViewport[options.axis] / oContent[options.axis];
      oScrollbar.obj.toggleClass('disable', oContent.ratio >= 1);
      oTrack[options.axis] = options.size == 'auto' ? oViewport[options.axis] : options.size;
      oThumb[options.axis] = Math.min(oTrack[options.axis], Math.max(0, ( options.sizethumb == 'auto' ? (oTrack[options.axis] * oContent.ratio) : options.sizethumb )));
      oScrollbar.ratio = options.sizethumb == 'auto' ? (oContent[options.axis] / oTrack[options.axis]) : (oContent[options.axis] - oViewport[options.axis]) / (oTrack[options.axis] - oThumb[options.axis]);
      setSize();
      if(!(oContent.ratio >= 1) && bKeepScroll){
        iScroll = CurrentScroll;
        if((iScroll + oViewport[options.axis]) > oContent[options.axis]) {
          iScroll = oContent[options.axis] - oViewport[options.axis];   
        }
        oContent.obj.css(sDirection, -iScroll);
        if((oScrollbar.ratio > 0) && (iScroll > 0)) {
          iPosition.now = iScroll / oScrollbar.ratio;
          oThumb.obj.css(sDirection, iPosition.now);
        }
      }
    };

tinyscrollbar

tinyscrollbar - no revert scroll

javascript, jquery

jQuery