height\n  }\n\n  _process() {\n    const scrollTop = this._getScrollTop() + this._config.offset\n    const scrollHeight = this._getScrollHeight()\n    const maxScroll = this._config.offset + scrollHeight - this._getOffsetHeight()\n\n    if (this._scrollHeight !== scrollHeight) {\n      this.refresh()\n    }\n\n    if (scrollTop >= maxScroll) {\n      const target = this._targets[this._targets.length - 1]\n\n      if (this._activeTarget !== target) {\n        this._activate(target)\n      }\n\n  ...