TypeScript 3.4 RC release, Microsoft Scripting Language
TypeScript is a language for application-scale JavaScript. It adds optional types, classes, and modules to JavaScript. It supports tools for large-scale JavaScript applications for any browser, for any host, on any OS. It compiles to readable, standards-based JavaScript. It supports much the same types (numbers, strings, structures, boolean values, and the like) as you would expect in JavaScript, with a convenient enumeration type thrown in to help things along.
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.
It compiles to clean, simple JavaScript code which runs on any browser, in Node.js, or in any JavaScript engine that supports ECMAScript 3 (or newer).
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, including those from ECMAScript 2015 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.
Changelog v3.4 RC