在Angular 2中动态显示/隐藏菜单栏

I'm currently working on a Angular 2 project. I implemented two components (1. header and 2. display page content). If I open the service, I start with login / register. At this time, I want to hide all other menu items. If I'm logged-in, I want to show all menu items.I'm currently working on a Angular 2 project. I