Lesson 9: Generics and Advanced Types

Generics

Generics let one function, interface, or class work with multiple types safely.

function identity<T>(value: T): T {
  return value;
}

Generic Arrays

function getFirstItem<T>(items: T[]): T {
  return items[0];
}

Union Types

let result: string | number;
result = "Pass";
result = 90;

Literal Types

type Direction = "left" | "right" | "up" | "down";

Intersection Types

type Person = { name: string };
type Worker = { company: string };
type Employee = Person & Worker;

Optional Chaining and Nullish Coalescing

console.log(user.contact?.email);
let finalValue = inputValue ?? "Default Text";

Summary

Generics and advanced types make TypeScript especially powerful for building flexible and scalable applications while preserving safety.