This template can be used to create new npm packages with some set standards.
Typescript is build on Javascript and is primarily used for catching errors and providing types for your code, see docs. Typescript files will compile to js and types (d.ts) in a dist folder.
Prettier and ESLint are defined as the default code formatter. I would recommend the Prettier - Code formatter extension when using VSCode as your default IDE.
Everything is optional, feel free to edit/delete any dependencies and files.