code: function ( y ){
  
          y = y < 0 ? 0 :y;
          y = y > this.range ? this.range : y;
  
          this.inner.style.top = - Math.floor( y / this.ratio ) + 'px';
          this.scroll.style.top = Math.floor( y ) + 'px';
  
          this.py = y;
  
          //this.onWheel = false;
  
      }
docs: ----------------------------------- Scroll