Amount validation pattern in Angular 7

Question

Hi All,

I have one field for amount. It will take only positive value and greater than 0.

So, I need pattern validation for angular 7.  

<input type="number" required #itemAmount="ngModel" name="itemAmount" [class.is-invalid]="itemAmount.invalid && itemAmount.touched" class="form-control" [(ngModel)]="appModel.itemAmount" placeholder="Approval Limit" min="1"/>