TypeScript Foundations: Union Types and Type Aliases

As you build larger applications, restricting variables to a single rigid data type can limit your code's flexibility. Understanding how to combine and customize types is essential for writing clean, scalable TypeScript. This written course guides you through the core concepts of union types and type aliases, enabling you to create highly adaptable type definitions. You will learn how to handle multiple potential types safely, reduce code duplication, and write self-documenting code that catches errors during development. What you'll learn: Understand the foundational syntax of union types to allow variables to hold multiple type options; Create custom, reusable type definitions using type aliases to simplify complex type signatures; Apply type narrowing techniques, including type guards and the typeof operator, to safely handle union types at runtime; Implement literal types and discriminated unions to model precise application states; Practice refactoring standard JavaScript code into strongly typed TypeScript structures through written exercises. The course begins with essential terminology and the basic mechanics of unions before moving into practical patterns for type composition and narrowing. You will read clear explanations and analyze step-by-step code snippets to solidify your understanding of modern type design. This course is designed for beginners who have a basic grasp of JavaScript and want to master TypeScript's type system. No advanced TypeScript experience is required. Start reading today to write safer, more expressive TypeScript code.