Always on the current ECMA standard
Your code is strongly typed, so you can safely refactor your code. When using VisualStudio, the TypeScript compiler is integrated in the built process, giving you errors and warnings about your code.
Functional & Object oriented
Available libraries and TypeScript definition files
There are serveral repositories for TypeScript Typings available. That means most of the common libraries has typings available so you can start building strongly typed code over common libraries. See https://github.com/DefinitelyTyped/DefinitelyTyped . Recently, the tsd tool used to search and install typings for your application has been replaced by this project https://github.com/typings/typings.