如何实现一个简单的购物车价格计算？

wen java案例 2026-06-05 294
<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">简单购物车 · 价格计算</title>
    <style>
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }
        body {
            background: linear-gradient(145deg, #f5f7fa 0%, #e9edf2 100%);
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
            padding: 1.5rem;
            margin: 0;
        }
        .cart-card {
            max-width: 760px;
            width: 100%;
            background: rgba(255, 255, 255, 0.7);
            backdrop-filter: blur(6px);
            -webkit-backdrop-filter: blur(6px);
            background-color: #ffffffdd;
            border-radius: 32px;
            padding: 2rem 2rem 2.2rem;
            box-shadow: 0 20px 36px -8px rgba(0, 0, 0, 0.15), 0 4px 12px rgba(0, 0, 0, 0.05);
            border: 1px solid rgba(255, 255, 255, 0.6);
            transition: all 0.2s;
        }
        h2 {
            display: flex;
            align-items: center;
            gap: 10px;
            font-weight: 600;
            font-size: 1.8rem;
            letter-spacing: -0.02em;
            color: #1f2a3a;
            margin-bottom: 1.8rem;
            border-bottom: 2px solid rgba(0, 0, 0, 0.04);
            padding-bottom: 0.75rem;
        }
        h2 small {
            font-size: 1rem;
            font-weight: 400;
            color: #5b6b7f;
            margin-left: auto;
            background: #eef2f6;
            padding: 0.3rem 0.9rem;
            border-radius: 30px;
            letter-spacing: 0.3px;
        }
        .cart-item {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            justify-content: space-between;
            background: white;
            padding: 1rem 1.25rem;
            border-radius: 20px;
            margin-bottom: 0.9rem;
            box-shadow: 0 2px 6px rgba(0, 0, 0, 0.02);
            border: 1px solid #f0f2f5;
            transition: 0.15s ease;
        }
        .cart-item:hover {
            border-color: #cbd5e1;
            box-shadow: 0 6px 12px -8px rgba(0, 20, 40, 0.12);
        }
        .item-info {
            display: flex;
            align-items: center;
            gap: 0.8rem;
            flex: 2 1 180px;
        }
        .item-name {
            font-weight: 550;
            font-size: 1.15rem;
            color: #182230;
        }
        .item-price {
            background: #eef3f9;
            padding: 0.2rem 0.8rem;
            border-radius: 40px;
            font-size: 0.85rem;
            font-weight: 500;
            color: #2b4b6f;
            white-space: nowrap;
        }
        .qty-control {
            display: flex;
            align-items: center;
            gap: 0.5rem;
            background: #f2f5f9;
            padding: 0.2rem 0.3rem;
            border-radius: 60px;
            margin: 0.4rem 0.6rem;
        }
        .qty-control button {
            background: transparent;
            border: none;
            width: 34px;
            height: 34px;
            font-size: 1.4rem;
            font-weight: 400;
            line-height: 1;
            color: #2c3e4f;
            cursor: pointer;
            border-radius: 40px;
            transition: 0.1s;
            display: inline-flex;
            align-items: center;
            justify-content: center;
        }
        .qty-control button:hover {
            background: #dce3eb;
            color: #0d1b2b;
        }
        .qty-control button:active {
            background: #cbd5e1;
            transform: scale(0.92);
        }
        .qty-num {
            min-width: 28px;
            text-align: center;
            font-weight: 600;
            font-size: 1.2rem;
            color: #0b1c2e;
        }
        .item-subtotal {
            min-width: 80px;
            text-align: right;
            font-weight: 600;
            font-size: 1.2rem;
            color: #1c314b;
            letter-spacing: 0.2px;
            padding-right: 0.2rem;
        }
        .delete-btn {
            background: none;
            border: none;
            color: #949faf;
            font-size: 1.3rem;
            cursor: pointer;
            padding: 0 0.2rem 0 0.8rem;
            transition: 0.1s;
            display: flex;
            align-items: center;
        }
        .delete-btn:hover {
            color: #c83a3a;
            transform: scale(1.1);
        }
        .total-section {
            margin-top: 2rem;
            padding-top: 1.6rem;
            border-top: 2px dashed #d0d9e3;
            display: flex;
            flex-wrap: wrap;
            justify-content: space-between;
            align-items: center;
            gap: 0.8rem 1rem;
        }
        .total-label {
            font-size: 1.2rem;
            font-weight: 500;
            color: #2b4059;
        }
        .total-amount {
            font-size: 2rem;
            font-weight: 650;
            letter-spacing: -0.02em;
            color: #0b1f33;
            background: #eef4fa;
            padding: 0.2rem 1.2rem;
            border-radius: 80px;
        }
        .reset-btn {
            background: #eef2f6;
            border: 1px solid #dce3ea;
            padding: 0.6rem 1.3rem;
            border-radius: 40px;
            font-weight: 500;
            color: #2e4a66;
            cursor: pointer;
            transition: 0.15s;
            font-size: 0.9rem;
            box-shadow: 0 1px 3px rgba(0,0,0,0.02);
        }
        .reset-btn:hover {
            background: #dce5ef;
            border-color: #b1c4d8;
            color: #001c34;
        }
        .reset-btn:active {
            transform: scale(0.96);
        }
        .empty-cart {
            text-align: center;
            padding: 2.2rem 0.5rem;
            color: #6a7b90;
            font-size: 1rem;
            background: #f8faff;
            border-radius: 40px;
            margin: 0.2rem 0;
        }
        .hidden {
            display: none !important;
        }
        .footer-note {
            margin-top: 1.6rem;
            font-size: 0.75rem;
            color: #8799ae;
            text-align: center;
            border-top: 1px solid #e3eaf1;
            padding-top: 1.2rem;
        }
        @media (max-width: 600px) {
            .cart-card { padding: 1.5rem; }
            .cart-item { flex-wrap: wrap; padding: 0.8rem 0.9rem; }
            .item-info { flex-basis: 100%; margin-bottom: 0.4rem; }
            .qty-control { margin-left: 0; }
            .item-subtotal { min-width: 70px; }
            .total-amount { font-size: 1.8rem; }
        }
    </style>
</head>
<body>
<div class="cart-card" role="main">
    <h2>
        🛒 购物车
        <small id="itemCount">3 件商品</small>
    </h2>
    <!-- 购物车容器 -->
    <div id="cartItemsContainer"></div>
    <!-- 底部结算区 -->
    <div class="total-section">
        <span class="total-label">合计</span>
        <span class="total-amount" id="totalPrice">¥0.00</span>
        <button class="reset-btn" id="resetCartBtn" aria-label="清空购物车">🗑️ 清空</button>
    </div>
    <div class="footer-note">点击 +/- 调整数量 · 删除商品</div>
</div>
<script>
    (function() {
        // ---------- 商品初始数据 ----------
        const INIT_ITEMS = [
            { id: 'item1', name: '无线蓝牙耳机', price: 249.00, quantity: 1 },
            { id: 'item2', name: '可折叠支架', price: 89.00, quantity: 2 },
            { id: 'item3', name: 'USB-C 数据线 (1m)', price: 39.90, quantity: 1 },
            { id: 'item4', name: '桌面收纳盒', price: 59.00, quantity: 1 }
        ];
        // 当前状态 (深拷贝)
        let cartItems = INIT_ITEMS.map(item => ({ ...item }));
        // DOM 元素
        const container = document.getElementById('cartItemsContainer');
        const totalPriceEl = document.getElementById('totalPrice');
        const itemCountEl = document.getElementById('itemCount');
        const resetBtn = document.getElementById('resetCartBtn');
        // ---------- 渲染购物车 ----------
        function renderCart() {
            // 过滤掉数量 <= 0 的商品（防御）
            cartItems = cartItems.filter(item => item.quantity > 0);
            // 如果购物车为空，显示空状态
            if (cartItems.length === 0) {
                container.innerHTML = `<div class="empty-cart">🛍️ 购物车是空的，点击「清空」恢复默认商品</div>`;
                updateTotalAndCount();
                return;
            }
            // 生成每个商品条目 HTML
            let html = '';
            cartItems.forEach(item => {
                const subtotal = item.price * item.quantity;
                html += `
                    <div class="cart-item" data-id="${item.id}">
                        <div class="item-info">
                            <span class="item-name">${escapeHtml(item.name)}</span>
                            <span class="item-price">¥${item.price.toFixed(2)}</span>
                        </div>
                        <div class="qty-control">
                            <button class="qty-btn minus" data-id="${item.id}" aria-label="减少数量">−</button>
                            <span class="qty-num">${item.quantity}</span>
                            <button class="qty-btn plus" data-id="${item.id}" aria-label="增加数量">+</button>
                        </div>
                        <span class="item-subtotal">¥${subtotal.toFixed(2)}</span>
                        <button class="delete-btn" data-id="${item.id}" aria-label="删除商品">✕</button>
                    </div>
                `;
            });
            container.innerHTML = html;
            updateTotalAndCount();
            // 重新绑定事件 (事件委托在容器上, 但为了防止内存溢出, 使用容器监听)
            // 已经在外部使用委托, 无需再绑定
        }
        // 简单的转义 (防止XSS 但数据可信, 仅做演示)
        function escapeHtml(text) {
            const div = document.createElement('div');
            div.textContent = text;
            return div.innerHTML;
        }
        // ---------- 更新总计和数量徽章 ----------
        function updateTotalAndCount() {
            const total = cartItems.reduce((sum, item) => sum + (item.price * item.quantity), 0);
            totalPriceEl.textContent = `¥${total.toFixed(2)}`;
            const count = cartItems.reduce((sum, item) => sum + item.quantity, 0);
            itemCountEl.textContent = `${count} 件商品`;
        }
        // ---------- 核心操作: 修改数量 / 删除 ----------
        function handleItemAction(target) {
            // 通过匹配最近的 .cart-item 获取商品 id
            const cartItemDiv = target.closest('.cart-item');
            if (!cartItemDiv) return;
            const id = cartItemDiv.dataset.id;
            if (!id) return;
            // 寻找商品索引
            const index = cartItems.findIndex(item => item.id === id);
            if (index === -1) return;
            // 判断操作类型
            if (target.classList.contains('plus')) {
                // 增加数量 (上限 99)
                if (cartItems[index].quantity < 99) {
                    cartItems[index].quantity += 1;
                } else {
                    alert('数量最多为 99');
                    return;
                }
                renderCart();
            } 
            else if (target.classList.contains('minus')) {
                // 减少数量 (最少为 1, 减到0则删除)
                if (cartItems[index].quantity > 1) {
                    cartItems[index].quantity -= 1;
                } else {
                    // 数量为1 再减→移除
                    cartItems.splice(index, 1);
                }
                renderCart();
            } 
            else if (target.classList.contains('delete-btn')) {
                // 直接删除该商品
                cartItems.splice(index, 1);
                renderCart();
            }
        }
        // ---------- 重置购物车 (清空后恢复默认) ----------
        function resetCartToDefault() {
            cartItems = INIT_ITEMS.map(item => ({ ...item }));
            renderCart();
        }
        // ---------- 事件监听 (利用事件委托) ----------
        container.addEventListener('click', function(e) {
            const target = e.target.closest('button');
            if (!target) return;
            // 只处理购物车容器内的按钮 (plus, minus, delete)
            if (target.classList.contains('qty-btn') || target.classList.contains('delete-btn')) {
                e.preventDefault();
                handleItemAction(target);
            }
        });
        // 重置按钮
        resetBtn.addEventListener('click', function(e) {
            resetCartToDefault();
        });
        // ---------- 初始化渲染 ----------
        renderCart();
        // 附加: 若用户误触键盘等, 保持界面统一
        console.log('✅ 简单购物车已启动 — 点击 +/- 修改数量，✕ 删除商品');
    })();
</script>
</body>
</html>