TypeScript Patterns

Go beyond basic types: generics, utility types, type guards, and advanced patterns that are expected at most companies in 2026.

16 exercises

mediumTypeScript

TypeScript Utility Types from Scratch

# Build Custom Utility Types Implement five essential TypeScript utility types from scratch without using the built-in...

typescriptutility-typesmapped-types+3

mediumTypeScript

Type-Safe Query Builder with Method Chaining

Build a type-safe QueryBuilder class that enforces method call order and prevents duplicate calls using TypeScript's typ...

mediumTypeScript

Generic Result Type Implementation

Implement a generic `Result<T, E>` type similar to Rust's Result enum. This type represents either a successful value (`...

mediumTypeScript

Type-Safe Event Emitter

Build a generic `EventEmitter<Events>` class that provides full type safety for event handling. The `Events` type param...

easyTypeScript

Generic Stack Implementation

Implement a generic `Stack<T>` class that provides last-in-first-out (LIFO) data structure functionality with full type...

easyTypeScript

Express Request Logging Middleware

Build an Express middleware function that logs information about every HTTP request and response. ## Requirements Your...

mediumTypeScript

Express Schema Validation Middleware

Create Express middleware that validates incoming request bodies against schema objects. The middleware should support:...

mediumTypeScript

Express Error Handling System

Build a robust error handling system for an Express application with three key components: 1. **Custom AppError Class**...

mediumTypeScript

Next.js Dynamic Routes with Static Generation

Create a Next.js-style dynamic route component that simulates the behavior of `[slug]/page.tsx` with `generateStaticPara...

hardTypeScript

Next.js On-Demand ISR Revalidation System

Build a system that simulates Next.js on-demand ISR (Incremental Static Regeneration) with revalidation capabilities. #...

mediumTypeScript

User Data Fetcher with State Management

Build a data fetching component that loads users from a mock API and manages all possible states. ## Requirements Impl...

mediumTypeScript

Todo List State Management

# Todo List Component Implement a `TodoList` class that manages todo items with full CRUD functionality. Each todo shou...

Page 1 of 2Next