E-commerce Shopping Cart

1class Product {
2  constructor(data) {
3    this.id = data.id || this.generateId();
4    this.name = data.name;
5    this.description = data.description;
6    this.price = data.price;
7    this.images = data.images || [];
8    this.category = data.category;
9    this.tags = data.tags || [];
10    this.variants = data.variants || [];
11    this.stock = data.stock || 0;
12    this.isActive = data.isActive !== false;
13    this.ratings = data.ratings || [];
14    this.createdAt = new Date(data.createdAt || Date.now());
15  }
16
17  getAverageRating() {
18    if (this.ratings.length === 0) return 0;
19    const sum = this.ratings.reduce((acc, rating) => acc + rating.score, 0);
20    return sum / this.ratings.length;
21  }
22
23  isInStock(quantity = 1) {
24    return this.stock >= quantity;
25  }
26
27  updateStock(quantity) {
28    this.stock = Math.max(0, this.stock + quantity);
29  }
30}
31
32class ProductCatalog {
33  constructor() {
34    this.products = new Map();
35    this.categories = new Map();
36    this.searchIndex = new Map();
37  }
38
39  addProduct(productData) {
40    const product = new Product(productData);
41    this.products.set(product.id, product);
42    this.updateSearchIndex(product);
43    return product;
44  }
45
46  searchProducts(query, filters = {}) {
47    let results = Array.from(this.products.values());
48
49    // Text search
50    if (query) {
51      const terms = query.toLowerCase().split(' ');
52      results = results.filter(product => {
53        const searchText = `${product.name} ${product.description} ${product.tags.join(' ')}`.toLowerCase();
54        return terms.every(term => searchText.includes(term));
55      });
56    }
57
58    // Apply filters
59    if (filters.category) {
60      results = results.filter(p => p.category === filters.category);
61    }
62
63    if (filters.priceMin !== undefined) {
64      results = results.filter(p => p.price >= filters.priceMin);
65    }
66
67    if (filters.priceMax !== undefined) {
68      results = results.filter(p => p.price <= filters.priceMax);
69    }
70
71    if (filters.inStock) {
72      results = results.filter(p => p.stock > 0);
73    }
74
75    // Sort results
76    const sortBy = filters.sortBy || 'name';
77    results.sort((a, b) => {
78      switch (sortBy) {
79        case 'price_asc': return a.price - b.price;
80        case 'price_desc': return b.price - a.price;
81        case 'rating': return b.getAverageRating() - a.getAverageRating();
82        case 'newest': return new Date(b.createdAt) - new Date(a.createdAt);
83        default: return a.name.localeCompare(b.name);
84      }
85    });
86
87    return results;
88  }
89}

1class ShoppingCart {
2  constructor() {
3    this.items = new Map();
4    this.discounts = [];
5    this.shipping = null;
6    this.listeners = new Set();
7  }
8
9  addItem(productId, quantity = 1, variant = null) {
10    const key = this.getItemKey(productId, variant);
11    const existingItem = this.items.get(key);
12
13    if (existingItem) {
14      this.updateQuantity(key, existingItem.quantity + quantity);
15    } else {
16      this.items.set(key, {
17        productId,
18        variant,
19        quantity,
20        addedAt: new Date()
21      });
22    }
23
24    this.notifyListeners('item_added', { productId, quantity, variant });
25    this.saveToStorage();
26  }
27
28  updateQuantity(itemKey, newQuantity) {
29    if (newQuantity <= 0) {
30      this.items.delete(itemKey);
31      this.notifyListeners('item_removed', { itemKey });
32    } else {
33      const item = this.items.get(itemKey);
34      if (item) {
35        item.quantity = newQuantity;
36        this.notifyListeners('quantity_updated', { itemKey, quantity: newQuantity });
37      }
38    }
39
40    this.saveToStorage();
41  }
42
43  calculateTotals(productCatalog) {
44    let subtotal = 0;
45    let totalItems = 0;
46
47    for (const [key, item] of this.items) {
48      const product = productCatalog.getProduct(item.productId);
49      if (product) {
50        subtotal += product.price * item.quantity;
51        totalItems += item.quantity;
52      }
53    }
54
55    const discountAmount = this.calculateDiscounts(subtotal);
56    const shippingCost = this.calculateShipping(subtotal, totalItems);
57    const tax = this.calculateTax(subtotal - discountAmount);
58    const total = subtotal - discountAmount + shippingCost + tax;
59
60    return {
61      subtotal,
62      discountAmount,
63      shippingCost,
64      tax,
65      total,
66      itemCount: totalItems
67    };
68  }
69
70  applyDiscount(discountCode) {
71    // Simulate discount validation
72    const validDiscounts = {
73      'SAVE10': { type: 'percentage', value: 10, minOrder: 50 },
74      'FREESHIP': { type: 'free_shipping', minOrder: 25 },
75      'WELCOME20': { type: 'percentage', value: 20, maxDiscount: 50, newCustomerOnly: true }
76    };
77
78    const discount = validDiscounts[discountCode];
79    if (!discount) {
80      throw new Error('Invalid discount code');
81    }
82
83    // Check if already applied
84    if (this.discounts.some(d => d.code === discountCode)) {
85      throw new Error('Discount already applied');
86    }
87
88    this.discounts.push({
89      code: discountCode,
90      ...discount,
91      appliedAt: new Date()
92    });
93
94    this.notifyListeners('discount_applied', { code: discountCode });
95    this.saveToStorage();
96  }
97
98  getItemKey(productId, variant) {
99    return variant ? `${productId}_${JSON.stringify(variant)}` : productId;
100  }
101
102  saveToStorage() {
103    const cartData = {
104      items: Array.from(this.items.entries()),
105      discounts: this.discounts,
106      shipping: this.shipping,
107      lastUpdated: new Date().toISOString()
108    };
109
110    localStorage.setItem('shopping_cart', JSON.stringify(cartData));
111  }
112
113  loadFromStorage() {
114    try {
115      const saved = localStorage.getItem('shopping_cart');
116      if (saved) {
117        const cartData = JSON.parse(saved);
118        this.items = new Map(cartData.items);
119        this.discounts = cartData.discounts || [];
120        this.shipping = cartData.shipping;
121      }
122    } catch (error) {
123      console.error('Failed to load cart from storage:', error);
124    }
125  }
126}