Non‐Functional‐Requirements - ganesh-agre/angular-ecommerce-app GitHub Wiki

⚙️ Step 2: Non-Functional Requirements – E-commerce App

Beyond features, a good frontend system is defined by its quality attributes — how fast, accessible, secure, and maintainable it is.

Here are the key non-functional goals for our Angular-based e-commerce store:

🚀 Performance

  • Use lazy loading for feature modules like cart, wishlist, and checkout.
  • Apply OnPush change detection to optimize rendering.

📱 Responsiveness

  • Implement a mobile-first layout with CSS Flex/Grid.
  • Use Angular’s BreakPointObserver if needed for dynamic layouts.

🔒 Security

  • Avoid XSS using Angular's built-in sanitization.
  • Protect routes with guards (auth, roles).
  • Store JWT securely (prefer HttpOnly cookie strategy).

♿ Accessibility

  • Follow WCAG 2.1 guidelines.
  • Use ARIA labels and proper semantic HTML.
  • Ensure full keyboard navigation (especially for product filters and checkout forms).

These NFRs guide every future design decision — from component strategy to folder structure, from routing to testing.

🧱 Reliability

  • Graceful fallback UIs for failed API calls (e.g., show error messages, retry options, empty state UI).
  • Use RxJS retry/backoff patterns for network resilience where appropriate.
  • Critical flows like checkout, cart updates, and login include optimistic updates with rollback handling.
  • Monitor key events via custom error handlers and global interceptors.
  • Detect and alert runtime errors using tools like Sentry, Firebase Crashlytics, or custom logging.

🧪 Combine with testing strategy to catch regressions early and ensure uptime through reliable user experiences.

📈 Scalability

  • Modular architecture using feature-based folders (e.g., /products, /cart, /orders) allows easy onboarding of new features.
  • State is managed centrally using NgRx or locally via Signals, enabling distributed development and horizontal scaling.
  • Feature modules are lazy loaded, ensuring performance even as the app grows.
  • Ready for micro frontends if needed in the future (e.g., separate admin panel, product engine, etc.).

🛠️ Maintainability

  • Uses DRY (Don't Repeat Yourself) principles via shared components, pipes, and services.
  • Follows Angular style guide: consistent naming, smart/dumb component separation, clear folder structure.
  • Includes CoreModule for singleton services and SharedModule for UI elements to reduce duplication.
  • Encourages single responsibility principle (SRP) for services and components.

🧪 Testing Strategy

Layer Approach Tooling
Unit Testing Pure component/service logic Karma + Jasmine
Integration Component with DOM interactions Angular Testing Utils
E2E Testing Simulated user flows Cypress or Playwright
  • Write unit tests for every service and pipe.
  • Cover component outputs and user interactions via integration tests.
  • Run E2E tests for cart, checkout, and auth flows.
  • Use TestBed for isolation and mocking dependencies.

🔁 Automated testing in CI pipelines is recommended for consistent build verification.

✅ These additions ensure that your e-commerce frontend isn’t just feature-complete, but also engineered to last — flexible to scale, easy to modify, and reliable in real-world use.