TypeScript starts from the same syntax and semantics that millions of JavaScript developers know today. Use existing JavaScript code, incorporate popular JavaScript libraries, and call TypeScript code from JavaScript.

TypeScript compiles to clean, simple JavaScript code which runs on any browser, in Node.js, or in any JavaScript engine.

Types enable JavaScript developers to use highly-productive development tools and practices like static checking and code refactoring when developing JavaScript applications.

Types are optional, and type inference allows a few type annotations to make a big difference to the static verification of your code. Types let you define interfaces between software components and gain insights into the behavior of existing JavaScript libraries.

TypeScript offers support for the latest and evolving JavaScript features and future proposals, like async functions and decorators, to help build robust components.

These features are available at development time for high-confidence app development but are compiled into simple JavaScript that targets ECMAScript 3 (or newer) environments.