TypeScript is a strongly typed programming language that builds on JavaScript. Developed by Microsoft under Anders Hejlsberg’s leadership, it adds optional static typing to JavaScript while remaining fully compatible with existing JavaScript code.
Origins
Microsoft released TypeScript in 2012 to address JavaScript’s scalability challenges in large codebases. The language adds type annotations that are erased at compile time, producing clean JavaScript that runs anywhere.
Key Features
TypeScript enhances JavaScript with:
- Static typing: Catch errors at compile time
- Type inference: Types deduced when not explicit
- Interfaces: Define object shapes
- Generics: Type-safe reusable components
- Enums: Named constants
- Decorators: Metaprogramming support
Design Philosophy
TypeScript follows key principles:
- JavaScript compatibility: Valid JS is valid TS
- Gradual typing: Add types incrementally
- Structural typing: Types compared by structure, not name
- Stay aligned with ECMAScript: Implement future JS features early
Impact
TypeScript transformed large-scale JavaScript development:
- Adopted by major frameworks (Angular, Vue 3)
- Used at Google, Microsoft, Airbnb, and many others
- Made refactoring large JavaScript codebases tractable
- Influenced JavaScript itself to add optional type proposals