A programming language, a superset of Javascript, TypeScript main feature is static typing, which makes it easier to work on larger projects. It enables static, strong typing, i.e. it monitors whether in the function that should accept a string (text) as a parameter, where there is no other type, such as a number. In addition, it upgrade object-oriented programming which, for example, introduces interfaces or abstract classes, improves cooperation with the code editor, and also allows you to declare interfaces for an API on the server side. This leads to the cooperation between the frontend and the backend being better. You can create files with the extension .d.ts that contain information about types only, useful when using libraries that are written in pure Javascript and do not have information about types. Javascript code is valid TypeScript code.

TypeScript Homepage