code: function scrollHandler(el){
              var state = getState(el);
              return throttle(function(event){
                  computeVisibleArea(el);
                  computeBarHeight(el); // fallback for an undetected content change
                  if (!state.barDragging) {
                      computeBarTop(el);
                      updateDragger(el, {withScrollingClasses: true});
                  }
              }.bind(this), state.config.scrollThrottle);
          }
docs: /*------------------------------------*\
  Events & Handlers
  \*------------------------------------