Hi
In cart view using + button you can exceed the max quantity of item. like if you have max 1 quantity in cart view you can add more then 1 items.
1st suggestion can be before this line we can add
if(this._data.quantityMax && this._data.maxQuantity < ( this._quantity+quantityInt )) return;
Exactly that variable which we are using here like
<ngcart-addtocart id="{{ item.id }}" name="{{ item.name }}" price="{{ item.price }}" quantity="{{item.quantity}}" quantity-max="{{ item.maxQuantity }}" data="item">Add to Cart</ngcart-addtocart>
In my case maxQuantity is that variable which can be use for this.

Best regards