Reactive form validation

<input id="name" class="form-control"
      formControlName="name" required >
<div *ngIf="name.invalid && (name.dirty || name.touched)"
    class="alert alert-danger">
  <div *ngIf="name.errors.required">
    Name is required.
  </div>
  <div *ngIf="name.errors.minlength">
    Name must be at least 4 characters long.
  </div>
  <div *ngIf="name.errors.forbiddenName">
    Name cannot be Bob.
  </div>
</div>