CODE EXAMPLE FOR TYPESCRIPT

handler for button in react typescript

const handleAddToCart = (clickedItem: CartItemType) => {
    setCartItems(prev => {
      // 1. Is the item already added in the cart?
      const isItemInCart = prev.find(item => item.id === clickedItem.id);

      if (isItemInCart) {
        return prev.map(item =>
          item.id === clickedItem.id
            ? { ...item, amount: item.amount + 1 }
            : item
        );
      }
      // First time the item is added
      return [...prev, { ...clickedItem, amount: 1 }];
    });
  };