TypeScript by Example
The essential skill for modern software development
TypeScript has transformed how we build software. As a typed superset of JavaScript, it brings compile-time type checking, enhanced IDE support, and enterprise-grade tooling to the world's most popular programming language.
From startups to Fortune 500 companies, TypeScript powers mission-critical applications at Google, Microsoft, Airbnb, Slack, and thousands of other organizations. It's not just a trend — it's the new standard for professional JavaScript development.
Why TypeScript Matters in 2026
In an era of complex web applications, microservices, and AI-powered tools, TypeScript has become the foundation of professional software development. Here's why leading companies and developers choose TypeScript.
Eliminate Runtime Errors
Catch bugs before they reach production. TypeScript's static type checking identifies errors at compile time, reducing debugging time by up to 15%.
AI-Ready Development
AI coding assistants like GitHub Copilot and Claude work dramatically better with TypeScript. Type annotations provide crucial context for smarter suggestions.
Enterprise Scale
Confidently refactor millions of lines of code. Types serve as contracts between teams, making large-scale applications manageable and maintainable.
Trusted by Industry Leaders
TypeScript powers the products you use every day
Core TypeScript
Master the fundamentals of TypeScript including variables, types, async programming, and design patterns.
Basics
4 examplesMaster the fundamentals of TypeScript including variables, functions, objects, and arrays. These core concepts form the foundation for everything else you'll learn.
Variables
TypeScript supports let and const for variable declarations with type inference and explicit type annotations.
Functions
Functions in TypeScript can have typed parameters and return types, with support for optional and default parameters.
Objects
Objects can be typed using interfaces or type aliases, providing structure and type safety.
Arrays
TypeScript arrays are typed collections with powerful methods for transformation and iteration.
Types
4 examplesExplore TypeScript's powerful type system including generics, union types, type guards, and utility types. Learn how to create flexible, reusable, and type-safe code.
Generics
Generics allow you to write reusable code that works with multiple types while maintaining type safety.
Union Types
Union types allow a value to be one of several types, enabling flexible yet type-safe code.
Type Guards
Type guards narrow types at runtime, helping TypeScript understand which type you're working with.
Utility Types
TypeScript provides built-in utility types for common type transformations.
Async
3 examplesLearn asynchronous programming patterns in TypeScript including Promises, async/await, and error handling. Essential for building modern web applications.
Promises
Promises represent eventual completion or failure of async operations, with full type support.
Async/Await
Async/await provides a cleaner syntax for working with Promises while maintaining full type safety.
Error Handling
Proper error handling in async code ensures robust applications with typed error states.
Patterns
4 examplesExplore design patterns and architectural best practices in TypeScript. Learn Singleton, Factory, Observer, and other proven patterns for scalable code.
Builder Pattern
The Builder pattern creates complex objects step by step with a fluent interface.
Factory Pattern
The Factory pattern creates objects without exposing instantiation logic.
Singleton Pattern
The Singleton pattern ensures a class has only one instance throughout the application.
Observer Pattern
The Observer pattern defines a subscription mechanism to notify objects about events.
Frontend
Build modern, type-safe user interfaces with popular frontend frameworks and libraries.
React
5 examplesBuild modern user interfaces with React and TypeScript. Learn typed components, hooks, context, and state management for robust frontend applications.
Components & Props
Type-safe React components with properly typed props, children, and default values.
Hooks
Type-safe React hooks including useState, useEffect, useRef, useReducer, and custom hooks.
Context API
Type-safe React Context for global state management with proper typing for providers and consumers.
Event Handling
Properly typed event handlers for forms, inputs, clicks, and other DOM events in React.
Form Libraries
Type-safe form handling with React Hook Form and Zod validation for robust form management.
Next.js
4 examplesMaster full-stack development with Next.js and TypeScript. Covers App Router, Server Components, API routes, and data fetching patterns.
Server Components
Type-safe Server Components with async data fetching and proper typing for Next.js App Router.
Server Actions
Type-safe Server Actions for form handling and mutations in Next.js with proper error handling.
API Routes
Type-safe API route handlers in Next.js App Router with request/response typing.
Middleware
Type-safe Next.js middleware for authentication, redirects, and request modification.
Angular
4 examplesBuild enterprise-grade applications with Angular and TypeScript. Learn components, services, dependency injection, and reactive forms.
Components
Type-safe Angular components with proper Input/Output decorators and lifecycle hooks.
Services & DI
Type-safe Angular services with dependency injection, HTTP client, and RxJS observables.
Reactive Forms
Type-safe Angular reactive forms with validation, custom validators, and form arrays.
Signals
Type-safe Angular Signals for reactive state management with computed values and effects.
Backend
Develop robust server-side applications with Node.js and enterprise-grade frameworks.
Node
3 examplesBuild server-side applications with TypeScript and Node.js. Covers file system operations, HTTP servers, and working with environment variables.
Express
3 examplesCreate web servers and APIs with Express.js and TypeScript. Learn routing, middleware, error handling, and building RESTful services.
Typed Routes
Type-safe Express routes with properly typed request parameters, body, and response.
Middleware
Type-safe Express middleware for authentication, validation, error handling, and logging.
Controllers & Services
Clean architecture with typed controllers, services, and repository patterns in Express.
NestJS
4 examplesBuild scalable server-side applications with NestJS, a progressive Node.js framework. Learn modules, controllers, providers, and decorators.
Modules & Controllers
Type-safe NestJS modules, controllers, and dependency injection with decorators.
Guards & Interceptors
Type-safe NestJS guards for authentication/authorization and interceptors for logging/transformation.
Pipes & Exception Filters
Custom validation pipes and exception filters for robust error handling in NestJS.
Testing
Type-safe unit and integration testing in NestJS with Jest and proper mocking.
Quick Start
Run the examples locally in seconds
$ npm install -g typescript ts-node$ npx ts-node basics/variables.ts