What are some common TypeScript design patterns for large-scale applications?

The Singleton pattern in large TypeScript applications ensures the class has no more than one instance, and it’s used for things like logging or configuration. The Factory pattern allows the dynamic object creation and provides flexibility by reducing dependencies. The Decorator pattern simply enhances classes or methods with functionality like caching or logging without changing their core logic. The Observer Pattern enables event-driven architecture, where changes to one object may trigger reactions across other objects. Dependency injection improves modularity and testability by providing dependencies externally. Altogether, these patterns keep TypeScript code bases scalable and maintainable.