Progressive Web Apps with React

The App Shell

Our last chapter was about adding home screen installation and push notifications--both meant to improve the user's experience by adding functionality--but, as we described in our user stories at the beginning of the book, one of the most important features of this app was its inclusiveness; it was a chat app for everyone, anyone, anywhere.

From a web app perspective, we can better rephrase that as "any connection, any speed." The biggest blocker of web application performance is network requests: how long it takes to load data over a poor connection.

Developers can fail to give performance its due attention, simply because we usually test our sites on speedy connections inside air-conditioned buildings in urban hubs. However, ...