Progressive Web Apps (PWA) is a popular software concept introduced in 2015 by Google that brought regular web apps on desktop and mobile to a whole new level. Employing Service Workers, Web App manifest, push-notifications, HTTPS, App Shell, etc., Google’s PWA policies imply these advanced solutions to strictly fit the following standards:

Reliable (parts of functionality are available offline);
Fast (in PWAs, most part of interactive elements and dynamic content is refreshed on the client-side);
Engaging (a PWA provides smooth and inviting user experience).
You can create a profitable, user-pleasing PWA solution for your Shopify-based eCommerce store as well. We’ll tell you how, but first, let’s figure out some essentials.
https://multi-programming.com/blog/pwa-for-shopify-stores-using-angular-2