code: function() {
  				var stepValue = (getTimestamp() - dt) / 1000 * self.options.scrollStep;
  
  				if (self.smoothScrollActive) {
  					self.value += stepValue * direction;
  					self.setValue(self.value);
  					self.triggerScrollEvent(self.value);
  
  					if (!isFinishedScrolling()) {
  						dt = getTimestamp();
  						raf(doScrollAnimation);
  					}
  				}
  			}
docs: animation step