TypeScript is JavaScript with syntax for types.
TypeScript is a strongly typed programming language which builds on JavaScript giving you better tooling at any scale.
JavaScript and More
TypeScript adds additional syntax to JavaScript to support a tighter integration with your editor. Catch errors early in your editor.
A Result You Can Trust
TypeScript code converts to JavaScript which runs anywhere JavaScript runs: In a browser, on Node.js or Deno and in your apps.
Safety at Scale
TypeScript understands JavaScript and uses type inference to give you great tooling without additional code.
Source: https://www.typescriptlang.org/