Method _onKeydown

src/cdk/menu/menu-item.ts:201–243

* Handles keyboard events for the menu item, specifically either triggering the user defined * callback or opening/closing the current menu based on whether the left or right arrow key was * pressed. * @param event the keyboard event to handle

(event: KeyboardEvent)

   * @param event the keyboard event to handle
   */
  _onKeydown(event: KeyboardEvent) {
    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)) {
          const nodeName = this._elementRef.nativeElement.nodeName;

          // Avoid repeat events on non-native elements (see #30250). Note that we don't do this
          // on the native elements so we don't interfere with their behavior (see #26296).
          if (nodeName !== 'A' && nodeName !== 'BUTTON') {
            event.preventDefault();
          }

          this.trigger({keepOpen: event.keyCode === SPACE && !this.closeOnSpacebarTrigger});
        }
        break;

      case RIGHT_ARROW:
        if (!hasModifierKey(event)) {
          if (this._parentMenu && this._isParentVertical()) {
            if (this._dir?.value !== 'rtl') {
              this._forwardArrowPressed(event);
            } else {
              this._backArrowPressed(event);
            }
          }
        }
        break;

      case LEFT_ARROW:
        if (!hasModifierKey(event)) {
          if (this._parentMenu && this._isParentVertical()) {
            if (this._dir?.value !== 'rtl') {
              this._backArrowPressed(event);
            } else {
              this._forwardArrowPressed(event);
            }
          }
        }
        break;
    }
  }

  /** Whether this menu item is standalone or within a menu or menu bar. */
  private _isStandaloneItem() {