Thanks, Saurabh.
Glad, you liked the article.
The implementation may vary based on the requirement there, the one that I have used to improve application performance is with the help of CacheStorage API.
In that is cache some of my application files such as(main.css etc), this way we can improve the application performance a lot.
There are other uses like to do background syncing(dedicated or shared worker), and using Push API to send and receive push notifications (ServiceWorker).