Method _toggleOnKeydown

src/cdk/menu/menu-trigger.ts:163–208

* Handles keyboard events for the menu item. * @param event The keyboard event to handle

(event: KeyboardEvent)

   * @param event The keyboard event to handle
   */
  _toggleOnKeydown(event: KeyboardEvent) {
    const isParentVertical = this._parentMenu?.orientation === 'vertical';
    switch (event.keyCode) {
      case SPACE:
      case ENTER:
        // Skip events that will trigger clicks so the handler doesn't get triggered twice.
        if (!hasModifierKey(event) && !eventDispatchesNativeClick(this._elementRef, event)) {
          this.toggle();
          this.childMenu?.focusFirstItem('keyboard');
        }
        break;

      case RIGHT_ARROW:
        if (!hasModifierKey(event)) {
          if (this._parentMenu && isParentVertical && this._directionality?.value !== 'rtl') {
            event.preventDefault();
            this.open();
            this.childMenu?.focusFirstItem('keyboard');
          }
        }
        break;

      case LEFT_ARROW:
        if (!hasModifierKey(event)) {
          if (this._parentMenu && isParentVertical && this._directionality?.value === 'rtl') {
            event.preventDefault();
            this.open();
            this.childMenu?.focusFirstItem('keyboard');
          }
        }
        break;

      case DOWN_ARROW:
      case UP_ARROW:
        if (!hasModifierKey(event)) {
          if (!isParentVertical) {
            event.preventDefault();
            this.open();
            event.keyCode === DOWN_ARROW
              ? this.childMenu?.focusFirstItem('keyboard')
              : this.childMenu?.focusLastItem('keyboard');
          }
        }
        break;
    }
  }

  /** Handles clicks on the menu trigger. */
  _handleClick() {