Prerequisite:

    loggedInUser = { id :1, name:"Naresh", role:"ADMIN"}

Task 1: Display a link if the loggedInUser is "ADMIN"

    <a *ngIf="loggedInUser=='ADMIN'">Welcome {{loggedInUser.name}} </a>

Task 2: Display the loggedInUser role

    <p>
        Welcome {{loggedInUser.name}} 
  <ng-container *ngIf="loggedInUser">
    ( {{loggedInUser.role}} )
  </ng-container>
    </p>

Task 3: Display Roles

    roles = ["USER","ADMIN", "TRAINER","MANAGER"];

    <p> Roles - 
     <ng-container *ngFor="let role of roles; let first=first; let last=last">
      <ng-container *ngIf="!first">,</ng-container>
      <ng-container *ngIf="last">and</ng-container>
      {{role}}
    </ng-container>.
    </p>