The Clever Trick That Lets a Website Work Offline
Service workers can keep useful pages available when the signal disappears, but only if the site plans for it.
The train enters a tunnel just as you open a saved article. Some websites keep working; others turn into an error page. An install icon alone does not explain the difference.
A helper between the page and the network
A service worker can intercept requests and respond with cached resources. It runs separately from the page and gives developers a way to design offline behaviour. The useful word is design: the site must decide what to save, when to update it and what to show when something is missing.
Editorial image from Blogdel's technology collection, used for illustration.
A reading app might save the article you selected but leave video downloads optional. A ticketing app might make the ticket available while requiring a connection for a new purchase. Both choices are more helpful than pretending every action works offline.
Test the actual promise
Open the item you need while connected, then test the app in airplane mode before relying on it during a journey. Look for a clear indication of what has been downloaded.
Stale information deserves special care. An offline timetable should reveal when it was saved rather than presenting yesterday's departure information as live. The best offline experience makes its limits visible while preserving the useful part of the service.
Editorial image from Blogdel's technology collection, used for illustration.
Sources and further reading
References
- Service Worker API | Mozilla · primary