$cart = &$_SESSION['cart']; // reference for performance
if ($final_quantity > $available_stock) // High quality: clip to available stock and notify user $final_quantity = $available_stock; $stock_warning = "Only $available_stock items available. Quantity adjusted.";
// --- HIGH QUALITY VALIDATION BLOCK --- if (!$product_id || $product_id <= 0) die(json_encode(['error' => 'Invalid product ID'])); addcartphp num high quality
// Validate CSRF token (prevents cross-site request forgery) if (!validateCsrfToken($_POST['csrf_token'] ?? '')) http_response_code(403); die(json_encode(['error' => 'Invalid security token']));
Introduction In the world of e-commerce, the "Add to Cart" button is the engine of revenue. A broken, slow, or insecure cart system can destroy conversion rates. When developers search for the phrase "addcartphp num high quality" , they are not just looking for any snippet of code. They are looking for a scalable, user-centric, and secure implementation that handles product quantities ( num ) with precision. $cart = &$_SESSION['cart']; // reference for performance if
// --- DATABASE LOOKUP (Prepared Statement) --- $pdo = getDbConnection(); $stmt = $pdo->prepare("SELECT id, name, price, stock_quantity FROM products WHERE id = ? AND status = 1"); $stmt->execute([$product_id]); $product = $stmt->fetch(PDO::FETCH_ASSOC);
A high-quality add-to-cart system requires a dynamic UI. Here is the HTML/JS that interacts with the above PHP script. 4.1 HTML Structure (Product Page) <div class="product" data-product-id="42"> <h3>Premium Widget</h3> <p>Price: $29.99</p> <div class="quantity-control"> <button class="qty-decrement" aria-label="Decrease quantity">-</button> <input type="number" id="qty-num" name="num" value="1" min="1" max="50" step="1"> <button class="qty-increment" aria-label="Increase quantity">+</button> </div> <button class="add-to-cart-btn" data-id="42">Add to Cart</button> <div class="cart-feedback"></div> </div> 4.2 JavaScript (High-Quality Event Handling) // high-quality-cart.js document.querySelectorAll('.add-to-cart-btn').forEach(btn => btn.addEventListener('click', async function(e) quantity < 1) quantity = 1; if (quantity > maxStock) quantity = maxStock; const formData = new URLSearchParams(); formData.append('id', productId); formData.append('num', quantity); formData.append('csrf_token', getCsrfToken()); // fetch from meta tag try const response = await fetch('/addcart.php', method: 'POST', headers: 'Content-Type': 'application/x-www-form-urlencoded', 'X-Requested-With': 'XMLHttpRequest' , body: formData ); const result = await response.json(); const feedbackDiv = this.closest('.product').querySelector('.cart-feedback'); if (result.success) feedbackDiv.innerHTML = `<span class="success">✓ $result.message (Total: $result.cart_count)</span>`; updateCartIcon(result.cart_count); // Optional: animate the cart icon else feedbackDiv.innerHTML = `<span class="error">❌ $result.error</span>`; setTimeout(() => feedbackDiv.innerHTML = '', 3000); catch (err) console.error('Cart error:', err); ); A broken, slow, or insecure cart system can
<?php // addcart.php - High Quality Implementation session_start(); require_once 'config/database.php'; require_once 'includes/csrf.php'; require_once 'includes/sanitize.php'; // Only accept POST requests for security if ($_SERVER['REQUEST_METHOD'] !== 'POST') http_response_code(405); die(json_encode(['error' => 'Method not allowed']));