Method _resetActiveOption

src/material/list/selection-list.ts:482–493

* Resets the active option. When the list is disabled, remove all options from to the tab order. * Otherwise, focus the first selected option.

()

   * Otherwise, focus the first selected option.
   */
  private _resetActiveOption() {
    if (this.disabled) {
      const activeItem = this._items.find(item => item.selected) || this._items.first;
      const index = activeItem ? this._items.toArray().indexOf(activeItem) : -1;
      this._setActiveOption(index);
      return;
    }

    const activeItem =
      this._items.find(item => item.selected && !item.disabled) || this._items.first;
    this._setActiveOption(activeItem ? this._items.toArray().indexOf(activeItem) : -1);
  }

  /** Returns whether the focus is currently within the list. */
  private _containsFocus() {