TypeScript

is a free and open source programming language developed and maintained by Microsoft. site

It is a strict superset of JavaScript, and adds optional static typing and class-based object-oriented programming – classes, interfaces, and generics – to the language. wikipedia , mdn

The goal of TypeScript is to help catch mistakes early through its type system and make JavaScript development more efficient. One of the big benefits is enabling IDEs to provide a richer environment for spotting common errors as you type the code.

Anders Hejlsberg, lead architect of C# and creator of Delphi and Turbo Pascal, has worked on the development of TypeScript. TypeScript may be used to develop JavaScript applications for client-side or server-side (Node.js) execution.

TypeScript is designed for development of large applications and transcompiles to JavaScript. As TypeScript is a superset of JavaScript, any existing JavaScript programs are also valid TypeScript programs.

TypeScript supports definition files that can contain type information of existing JavaScript libraries, much like C/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 like 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, transcompiled to JavaScript and licensed under the Apache 2 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.