TypeScript is a programming language developed by Microsoft. It was first published in 2012. The goal is to enhance JavaScript with new features which should be implemented in the future version of ECMAScript (ECMAScript 6).
ECMAScript 6, which should come with the new features, is not supported by many common browsers and it will take some
time until compatibility can be guaranteed.
Therefore, Microsoft decided to invent TypeScript which already makes it
possible to make use of these new features including: optional static types, generics, namespaces etc.
Also strongly typed variables are featured in order to prevent runtime errors.
One of the main reasons it was invented is to provide maintainability of the code written for a web application.
Many features are taken from the programming language C# since one of the leading
inventors of TypeScript also invented C#.
Under the following address one can easily write and test TypeScript inside the browser: http://www.typescriptlang.org/Playground