getAffixType(){
        this._calcDimensionsWithScroll();
        var dims = this.dimensions;
        var colliderTop = dims.viewportTop + dims.topSpacing;
        var affixType = this.affixedType;

       if( colliderTop <= dims.containerTop || dims.containerHeight <= dims.sidebarHeight ){
          dims.translateY = 0;
          affixType = 'STATIC';
        } else {
          affixType = ( 'up' === this.direction ) ? 
            this._getAffixTypeScrollingUp() : this._getAffixTypeScrollingDown();
        }

        // Make sure the translate Y is not bigger than container height.
        dims.translateY = Math.max(0, dims.translateY);
        dims.translateY = Math.min(dims.containerHeight, dims.translateY);
        dims.translateY = Math.round(dims.translateY);
  
        dims.lastViewportTop = dims.viewportTop;
        return affixType;
      }
Gets affix type of sidebar according to current scroll top and scrolling direction.
@public
@return {String|False} - Proper affix type.