Cart is not updating when adding to cart

Hi Team

I need some help and been stuck to this issue, the issue when inspecting by debugging on the server side i am getting 200 status. But on the client side i am getting failed to add to item. What exactly am i doing wrong?

// client side code

     

                            
                            
                             0
                             
                             



            View Detail
            
            Add To Cart
        


// jquery code
$(document).ready(function() {
  $('.add-to-cart-btn').on('click', function(e) {
    e.preventDefault();

    var id = $(this).attr("id");
    var product_item = $("#product-item").val();
    var price = $("#price").val();
    var product_img = $("#product_img").val();
    var quantity = $("#quantity").val();
    // Send an AJAX request to update the cart in the database
    $.ajax({
      url: 'update-cart.php',
      method: 'POST',
      data: { id: id, product_item:product_item, price:price, product_img:product_img, quantity:quantity},
      success: function(response) {
        // Handle the response from the server
        if (response.success) {
          // Update the cart badge count
          var cartBadge = $('.fa-shopping-cart + .badge');
          var cartCount = parseInt(cartBadge.text());
          cartBadge.text(cartCount + 1);
        } else {
          // Handle the error scenario
          alert('Failed to add item to the cart. Please try again.');
        }
      },
      error: function() {
        alert('An error occurred while processing your request. Please try again later.');
      }
    });
  });
});

// server side

setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

            // Update the cart item with the new quantity or perform other operations
            // Example: Update the quantity in the cart table
            $stmt = $conn->prepare("UPDATE cart SET quantity = :quantity WHERE id = :itemId");
            $stmt->bindParam(':quantity', $quantity);
            $stmt->bindParam(':itemId', $id);
            $stmt->execute();

            // Return a success response
            $response = ['success' => true];
            echo json_encode($response);
            exit; // Stop executing further code
        } catch (PDOException $e) {
            // Return an error response
            $response = ['success' => false, 'error' => $e->getMessage()];
            echo json_encode($response);
            exit; // Stop executing further code
        }
    } else {
        echo json_encode(['success' => false, 'error' => 'Invalid request']);
    }
} else {
    echo json_encode(['success' => false, 'error' => 'Invalid request']);
}
?>