ng-bootstrap date format starts with zero

I am using angular with ng-bootstrap date component. Datepicker working well. But when I select today date shows as 2018-11-6.

I need change format like 2018-11-06 (leading zero). How can I change it?

  <div class="input-group">
      <input class="form-control" placeholder="yyyy-mm-dd"
             name="mydate" [(ngModel)]="bankDetailDate" ngbDatepicker #d="ngbDatepicker">
      <div class="input-group-append">
        <button class="btn btn-outline-secondary fa fa-calendar" (click)="d.toggle()" type="button"></button>
      </div>
    </div>