What does registerServiceWorker do in React JS?

• The serviceworker is a web API that helps you cache your assets and other files

• Because of that, when the user is offline or on slow network, he/she can still see results on the screen.

• Also It helps you build a better user experience, that's what you should know about service worker's for now. It's all about adding offline capabilities to your site.

WHAT IS POSTMAN?

Postman is a great tool for prototyping APIs, and it also has some powerful testing features. 

Postman: The Complete API Development Environment

1)A complete Toolchain for API Development
Postman was designed from the ground up, to support all aspects of API development. Postman's apps are built on a single underlying layer, ensuring consistent performance and user experience.


2)Mirrors your existing API Development workflow
Postman has features for every API developer: request building, tests & pre-request scripts, variables, environments, and request descriptions, designed to work seamlessly together. Postman was designed to make your current workflow faster and better.


3)Designed to support every API developer

Postman has options for the developer in everyone:

• Mac, Windows & Linux Apps
• Individual and team options
• Multiple integrations, including support for Swagger & RAML formats