updateSticky(event = {}){
        if( this._running ) return;
        this._running = true;
  
        ((eventType) => {
          requestAnimationFrame(() => {
            switch( eventType ){
              // When browser is scrolling and re-calculate just dimensions
              // within scroll. 
              case 'scroll':
                this._calcDimensionsWithScroll();
                this.observeScrollDir();
                this.stickyPosition();
                break;
  
              // When browser is resizing or there's no event, observe width
              // breakpoint and re-calculate dimensions.
              case 'resize':
              default: 
                this._widthBreakpoint();
                this.calcDimensions();
                this.stickyPosition(true);
                break;
            }
            this._running = false;
          });
        })(event.type);
      }
Switches between functions stack for each event type, if there's no 
event, it will re-initialize sticky sidebar.
@public