What do you mean by TypeScript?

TypeScript is created by Microsoft, a typed superset of JavaScript which adds the optional types, async/await, classes including several other features and then compiles to the plain JavaScript. Angular is entirely built in TypeScript and is being used as a primary language.

TypeScript can be installed globally as,

The AngularJS uses JavaScript while the Angular2 and its above version uses the TypeScript, which is basically the superset of JavaScript.