const handleAddToUpdate = (selecteInventory) => { let newCart = []; const exists = inventorys.find(inventory => inventory.quantity === selecteInventory.quantity); if (!exists) { selecteInventory.quantity = parseInt(); newCart = [...inventorys, selecteInventory]; } else { const rest = inventorys.filter(inventory => inventory.quantity !== selecteInventory.quantity); exists.quantity = exists.quantity + 1; newCart = [...rest, exists]; } setInventorys(newCart); // addToDb(selecteInventory.id); } <button className='btn btn-primary' onClick={() => handleAddToUpdate(inventory.quantity)}>UPDATE</button>`