SOLID Principles in JavaScript

Which SOLID principle suggests that classes should be small and focused?

class Order {
  calculateTotal() { /* ... */ }
  validateOrder() { /* ... */ }
  processPayment() { /* ... */ }
  generateInvoice() { /* ... */ }
  sendConfirmationEmail() { /* ... */ }
  updateInventory() { /* ... */ }
  generateShippingLabel() { /* ... */ }
  updateCustomerHistory() { /* ... */ }
}

Interface Segregation Principle
Single Responsibility Principle
This code violates the Single Responsibility Principle (SRP). The Order class handles multiple responsibilities: order calculation, validation, payment processing, invoice generation, email notifications, inventory management, shipping, and customer history. Each of these should be handled by separate classes to improve maintainability, testability, and reduce the risk of changes in one area affecting others.
Open/Closed Principle
Dependency Inversion Principle

Next Question (20/20)