| null) {\n // Ignore the cases where the `portal` is set to a falsy value before the lifecycle hooks have\n // run. This handles the cases where the user might do something like ``\n // and attach a portal programmatically in the parent component. When Angular does the first CD\n // round, it will fire the setter with empty string, causing the user's content to be cleared.\n if (this.hasAttached() && !portal && !this._isInitialized) {\n return;\n }\n\n if (this.hasAttached()) {\n super.detach();\n }\n\n if (portal) {\n super.attach(portal);\n }\n\n this._attachedPortal = portal;\n }\n\n /** Emits when a portal is attached to the outlet. */\n @Output() attached: EventEmitter =\n new EventEmitter();\n\n /** Component or view reference that is attached to the portal. */\n get attachedRef(): CdkPortalOutletAttachedRef {\n return this._attachedRef;\n }\n\n ngOnInit() {\n this._isInitialized = true;\n }\n\n ngOnDestroy() {\n super.dispose();\n this._attachedPortal = null;\n this._attachedRef = null;\n }\n\n /**\n * Attach the given ComponentPortal to this PortalOutlet using the ComponentFactoryResolver.\n *\n * @param portal Portal to be attached to the portal outlet.\n * @returns Reference to the created component.\n */\n attachComponentPortal(portal: ComponentPortal