Method _backArrowPressed

src/cdk/menu/menu-item.ts:254–266

* Handles the user pressing the back arrow key. * @param event The keyboard event.

(event: KeyboardEvent)

   * @param event The keyboard event.
   */
  private _backArrowPressed(event: KeyboardEvent) {
    const parentMenu = this._parentMenu!;
    if (this._menuStack.hasInlineMenu() || this._menuStack.length() > 1) {
      event.preventDefault();
      this._menuStack.close(parentMenu, {
        focusNextOnEmpty:
          this._menuStack.inlineMenuOrientation() === 'horizontal'
            ? FocusNext.previousItem
            : FocusNext.currentItem,
        focusParentTrigger: true,
      });
    }
  }

  /**
   * Handles the user pressing the forward arrow key.