resetPosition() {
    // Position on the main scroller (offset)
    // it is independent from slide index
    this._currPositionIndex = 0;
    this._prevPositionIndex = 0; // This will force recalculation of size on next resize()

    this.slideWidth = 0; // _containerShiftIndex*viewportSize will give you amount of transform of the current slide

    this._containerShiftIndex = -1;
  }
Reset X position of the main scroller to zero