Service workers act as proxy servers that handle network requests inside your app. This makes it possible to make your app work offline, but even if you don't need offline support (or can't realistically implement it because of the type of app you're building), it's often worth using service workers to speed up navigation by precaching your built JS and CSS.

However, if these timeouts are moved into a web worker, they should run to time and not get de-prioritised by the browser.

v1 tabs tightly couple to their v1 Cache; v2 tabs tightly couple to their v2 Cache. This tight coupling makes them “application caches.” The app must be completely shut down (all tabs closed) in order to upgrade atomically to the newest cache of code.

If a Service Worker fails, it’s possible to break an entire website in ways that we can’t fix on the server side (or at least, not right away). Imagine this: your site appears to be down, but refreshing the page won’t help, because the browser isn’t even talking to your server; it’s just talking to your broken Service Worker.

As programmers, we sometimes have to work on tricky stuff, but then we say, “Well, it’s not rocket science.” But Service Workers are rocket science.

Service Workers are very powerful. They allow offline functionality, push notifications, content caching, and more. They have a short lifetime, and the way they work is by waking up when they get an event (e.g., network requests, push notifications, connectivity changes) and then they start running only as long as the process needs it.

Service Workers are also helpful for offline caching and performance. You can write code to cache your application shell to work offline and populate its content using JavaScript.