Text Input for Positive Integers Only [Angular]

I’m trying to make a number input that is for only positive numbers. I have the following html:

<button class="minus-btn" (click)="minus()" type="button" name="button">
<img src="../assets/images/minus.svg" alt="minus" />
</button>
<input ng-pattern="^(0|\+?[1-9]\d*)$" class="num" name="quantity" [value]="quantity" type="number" min="0">
<button class="plus-btn" (click)="plus()" type="button" name="button">
<img src="../assets/images/plus.svg" alt="plus" /></button>

As you can see, I’ve implemented ng-pattern and min value but neither one works. In the controller:

quantity: number=1;
i=1;

plus(){
this.i++;
this.quantity=this.i;
}

minus(){
this.i–;
this.quantity=this.i;
}

When I add the following to the controller, I get the error " Property ‘match’ does not exist on type ‘number’"

this.quantity.match(/^(0|+?[1-9]\d*)$/g);

The correct solution was posted at: https://www.c-sharpcorner.com/forums/text-input-for-positive-integers-only