Review: Classes and Generics
Review how TypeScript’s class system and generics enforce safety, enable reuse, and bring clarity to object-oriented and parametric design.
We'll cover the following...
- Classes: Structure with boundaries
- Initialization: Deliberate and complete
- Access modifiers: Control what’s visible
- Abstract classes: Structure and enforcement
- Generics: Reusable logic, exact types
- Generic type aliases and interfaces: Reusable patterns
- Generic classes: Type-safe containers with behavior
- What was reinforced?
This chapter introduced two of the most expressive features in the language: classes, for modeling structure and behavior with guarantees and generics, for designing reusable logic that stays type-safe across contexts.
Together, they elevate TypeScript from a typed JavaScript helper to a full-scale modeling language for real-world architecture.
Let’s review what we made possible.
Classes: Structure with boundaries
In TypeScript, a class is more than a shape—it’s a set of guarantees. Fields must be declared and initialized. Behavior must be typed. Constructors must be complete. The compiler ensures nothing is left ambiguous.
class User {constructor(public name: string, private email: string) {}greet(): string {return `Welcome, ${this.name}`;}}
Fields are created and initialized in a single step using parameter properties.
Access modifiers control visibility.
Method return types are explicit and enforced.
This is the structure we can rely on—every time an instance is created. ...