Angular 2- using *ngIf with multiple conditions

You can move these multiline conditions and complex conditions to your component method as below

showLogout(){
    if(this.authService.userLoggedIn()== true && this.authService.adminLoggedIn() == false)
        return true;
    else
        return false;
}

Also, as the angular4 has *ngIf and else you can use it as

 <div *ngIf="showLogout();then userLogout else adminlogout"></div>

<ng-template #userLogout><a (click)="onUserLogoutClick()" href="#">Logout</a></li></ng-template>
<ng-template #adminlogout><a (click)="onAdminLogoutClick()" href="#">Logout</a></li></ng-template>

I think should be create a boolean properties in component and using it. In stead of writing function or complex expression in template. Function in template reduce performance. Complex expression make it not readble and maintainable.

authService.userLoggedIn() or authService.adminLoggedIn() in your expression wouldn't keep your template informed about who is logged in as your function is invoked only once.

Try make them getter in your service:

  get userLoggedIn(): boolean {
    return this.who.user; // your logic
  }

Then in your template:

<li *ngIf="authService.userLoggedIn && !authService.adminLoggedIn"...