_getAffixTypeScrollingUp(){
        var dims = this.dimensions;
        var sidebarBottom = dims.sidebarHeight + dims.containerTop;
        var colliderTop = dims.viewportTop + dims.topSpacing;
        var colliderBottom = dims.viewportBottom - dims.bottomSpacing;
        var affixType = this.affixedType;

        if( colliderTop <= dims.translateY + dims.containerTop ){
          dims.translateY = colliderTop - dims.containerTop;
          affixType = 'VIEWPORT-TOP';
        
        } else if( dims.containerBottom <= colliderBottom ){
          dims.translateY = dims.containerBottom - sidebarBottom;
          affixType = 'CONTAINER-BOTTOM';

        } else if( ! this.isSidebarFitsViewport() ){

          if( dims.containerTop <= colliderTop && 
              (0 !== dims.translateY && dims.maxTranslateY !== dims.translateY) ){
            affixType = 'VIEWPORT-UNBOTTOM';
          } 
        }

        return affixType;
      }
Get affix type while scrolling up.
@private
@return {String} - Proper affix type of scrolling up direction.