Calculate Row of Quantity

Im trying to Calculate all row of Quantity By following Code Below…

           calculateTotal() {
				return this.form.items.reduce((total, item) => {
					return total + item.quantity;
				}, 0);
			},

But it show wrong result
Screenshot%20at%202020-01-15%2010-31-57

Any Help??

Hi. The content of the table is strings I think. This is why 1+2 is 12 instead of three. Convert the to numbers before adding them

calculateTotal() {
  return this.form.items.reduce((total, item) => {
    return total + Number(item.quantity);
  }, 0);
},