code: function handleItemKeypress(e) {
      const itemIndex = NodeListUtils.findNodeWithFirstChar(this.itemEls, e.key);
  
      if (itemIndex !== -1) {
          this.rovingTabindex.index = itemIndex;
      }
  }
docs: For any key that corresponds to a printable character, move focus to
  the first menu item whose label begins with that character.
  https://www.w3.org/TR/wai-aria-practices-1.1/#menu
  @param {KeyboardEvent} e