title: disable ng-bootstrap date and time for previous dates in angular7
body: <h1>html</h1>
  
  <pre><code>     &lt;ngb-datepicker (select)="onDateSelect($event)" [(ngModel)]="datePickerModel"&gt;&lt;/ngb-datepicker&gt;
  
   &lt;ngb-timepicker [meridian]="meridian" [(ngModel)]="time" class="fromTimePick"&gt;
                  &lt;/ngb-timepicker&gt;
  </code></pre>
  
  <p>How to disable the calendar dates for past days i.e. disabling days before today and time before now (ie disable past time before current time with respect to current date) ?</p>