How to force service worker to update?

Question

I'm using sw-precache to generate my service work with Polymer CLI build process, so it's intended to update the hash of updated files to signal a need to update the cache. But my updated content is not being replaced in cache, so it's getting an old version if I refresh with ctrl+r but the new version if I refresh with ctrl+shift+r. A reason for that can be that my service worker is not being updated.

This doc states that

If there is even a byte's difference in the service worker file compared to what it currently has, it considers it new.

, but what if my new service worker didn't change a byte? (as it happens if just one hash has changed). How to configure the sw-precache to update the service work at every new request?

Answer 1

As the previous answers stated, there is a 1 day (24hr) built-in limit for the browser to look for updates to the service worker, but what you need to be mindful of is you still need to call .update() on your ServiceWorkerRegistration object otherwise the original version of the file will be used.

While testing changes in Chrome, I always right-click on the refresh button and select 'Empty Cache and Hard Reset' (options are available when developer tools are open) when working on my service worker script.

Answer 2

'sw-precache' has been superseded by Workbox which generates hashes for the files you want to precache and adds those to the source code of your service worker (I don't know if sw-precache works the same way, Jeff's answer suggests it does). If any of the files you want to precache change -- and you re-run your build -- the updated hashes in your service worker are updated which pretty much guarantees the service worker will be "at least one byte different".

When you reload (ctrl-r) or re-visit your app the browser will fetch again the service worker that was registered for it. And, if that service worker has changed, it will be "queued up" to manage the app. But it won't start managing the app until you close all tabs with the app open, and then open a new one.

When you hard refresh (shift-ctrl-r) it’ll always load without a controller which is not the same as using your new service worker.

For testing during development, I use skip waiting in devtools to make the new service worker replace the old one without waiting for me to close all the tabs.