TypeScript
Noun · Development · Origin: 2012
Definitions
TypeScript is a strongly typed programming language created by Microsoft that builds on JavaScript by adding optional static type annotations. It compiles (or more precisely, transpiles) to plain JavaScript, meaning TypeScript code runs anywhere JavaScript runs: browsers, Node.js, Deno, and serverless platforms. TypeScript's type system catches errors at compile time that would otherwise surface as runtime bugs, such as accessing properties on undefined values, passing wrong argument types, or mismatched function signatures. The type system includes features like interfaces, generics, union and intersection types, type guards, mapped types, and conditional types, enabling precise modeling of complex data shapes. TypeScript supports both gradual adoption (you can mix typed and untyped code) and strict mode for maximum type safety. The language integrates deeply with modern editors like VS Code, providing autocomplete, inline documentation, and refactoring tools powered by type information. TypeScript has become the standard for large-scale JavaScript projects and is used by Angular, many React codebases, Vue 3, and thousands of npm packages that ship type declarations.
In plain English: JavaScript with added safety nets — it catches many common mistakes before your code even runs, by letting you specify what types of data variables should hold.
Etymology
- 2012
- Microsoft publicly releases TypeScript, designed by Anders Hejlsberg (creator of C# and Turbo Pascal) to add optional static types to JavaScript
- 2016
- Angular 2 adopts TypeScript as its primary language, giving it massive ecosystem momentum
- 2023
- TypeScript surpasses JavaScript in developer surveys for new projects, completing a decade-long shift
Origin Story
Microsoft's answer to JavaScript's 'anything goes' philosophy
**TypeScript** was created at Microsoft by a team led by **Anders Hejlsberg** — the same language designer who created Turbo Pascal, Delphi, and C#. It was publicly announced in October 2012 after two years of internal development.
The problem TypeScript addressed was scale. JavaScript was designed in 10 days in 1995 for small browser scripts, but by 2010, companies like Microsoft, Google, and Facebook were building applications with millions of lines of JavaScript. Dynamic typing, which makes small scripts flexible and quick, became a liability at scale. Bugs that a type system would catch at compile time instead appeared at runtime, often in production.
Hejlsberg's key design decision was to make TypeScript a **strict superset** of JavaScript: any valid JavaScript is valid TypeScript. This meant teams could adopt it incrementally, file by file, without rewriting their codebase. The gradual adoption path proved crucial. By 2023, TypeScript had become one of the most popular programming languages in the world, and many developers now consider writing untyped JavaScript at scale to be almost reckless.
Coined by: Anders Hejlsberg / Microsoft
Context: Microsoft, publicly announced October 2012
Fun fact: Anders Hejlsberg has been designing programming languages for over 40 years. He's one of the few people whose language designs span the Turbo Pascal era (1983), the enterprise Java competitor era (C#, 2000), and the modern web era (TypeScript, 2012).