TypeScript

TypeScript is an open-source programming language developed and maintained by Microsoft. It is a strict syntactical superset of JavaScript, and adds optional static typing to the language. TypeScript is designed for development of large applications and transcompiles to JavaScript. As TypeScript is a superset of JavaScript, existing JavaScript programs are also valid TypeScript programs. TypeScript may be used to develop JavaScript applications for both client-side and server-side (Node.js) execution. There are multiple options available for transcompilation. Either the default TypeScript Checker can be used,, or the Babel compiler can be invoked to convert TypeScript to JavaScript.TypeScript supports definition files that can contain type information of existing JavaScript libraries, much like C++ header files can describe the structure of existing object files. This enables other programs to use the values defined in the files as if they were statically typed TypeScript entities. There are third-party header files for popular libraries such as jQuery, MongoDB, and D3.js. TypeScript headers for the Node.js basic modules are also available, allowing development of Node.js programs within TypeScript.The TypeScript compiler is itself written in TypeScript and compiled to JavaScript. It is licensed under the Apache 2.0 License. TypeScript is included as a first-class programming language in Microsoft Visual Studio 2013 Update 2 and later, beside C# and other Microsoft languages. An official extension allows Visual Studio 2012 to support TypeScript as well.Anders Hejlsberg, lead architect of C# and creator of Delphi and Turbo Pascal, has worked on the development of TypeScript.

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 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.

TypeScript is being developed on GitHub. The TypeScript compiler is implemented in TypeScript and can be used in any JavaScript host.