set _scrollTop(top) {
      if (this.scrollTarget === this._doc) {
        window.scrollTo(window.pageXOffset, top);
      } else if (this._isValidScrollTarget()) {
        this.scrollTarget.scrollTop = top;
      }
    }
/**
     * Sets the number of pixels that the content of an element is scrolled
     * upward.
     *
     * @type {number}
     */
Sets the number of pixels that the content of an element is scrolled
upward.

@type {number}
Sets the number of pixels that the content of an element is scrolled upward . @type { number }
set _scrollTop(top) {
      if (this.scrollTarget === this._doc) {
        window.scrollTo(window.pageXOffset, top);
      } else if (this._isValidScrollTarget()) {
        this.scrollTarget.scrollTop = top;
      }
    }
set _scrollTop ( top ) { if ( this . scrollTarget === this . _doc ) { window . scrollTo ( window . pageXOffset , top ) ; } else if ( this . _isValidScrollTarget ( ) ) { this . scrollTarget . scrollTop = top ; } }
Sets the number of pixels that the content of an element is scrolled
 upward.
Sets the number of pixels that the content of an element is scrolled upward .