Introduction

The Typescript language verifies your Javascript code ahead of time with static type checking. Javascript is a dynamic programming language where we can do all sorts of crazy things, like reference variables that don't exist or work with unknown objects. The code is interpreted by a browser-- but if your code is broken, you won't catch it until runtime when the browser throws an error.

Typescript prevents errors like this from ever happening by extending the Javascript language with types. The language is a strict superset of Javascript, which means you can write plain JS in a .ts file, with all of the TS extra features being completely optional.