Make it possible to pass configurations options to the service worker from the main thread

[TomasHubelbauer]

Hi, I am following the documentation on how to use the Firebase JavaScript SDK, specifically I am interested in FCM:
https://firebase.google.com/docs/cloud-messaging/js/receive#setting_notification_options_in_the_service_worker

The documentation states that alongside the JS SDK itself, I have to add a SW file as per the link above. I did that. Now turning the sample code in the documentation into production-ready code, I am getting rid of the hardcoded configuration strings, pulling them from my app's configuration instead.

However I am running into an issue doing this for the service worker. I can't access the main thread directly from the service worker thread, so it appears my only option is to use something like MessageChannel, Broadcast or the Client API.

But I can't help but think this is a common scenario the SDK already has an answer for, or at least, should; would folks agree? Would it be possible to have the SDK ship an API method for passing configuration options to the worker and be able to pick up the payload in the worker and initialize the SDK there as well based on the passed options?

I can and will for now do this myself using Broadcast, but IMO service workers are super fiddly to set up and make work right so I'd trust an SDK-provided solution over my own.

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[laurentpayot]

@TomasHubelbauer you can also transmit configuration options to the service worker via URL parameters. For instance:

• in the main thread

const LANG = 'en'

navigator.serviceWorker.register(`/service-worker.js?lang=${LANG}`})

• in the service worker

const LANG = new URL(location.href).searchParams.get('lang')

Hope it helps…

[TomasHubelbauer]

@laurentpayot The service worker is registered automatically by the Firebase JS SDK so there is no control over how that process is done, but this is a great tip for using service workers in general! Thank you

[DellaBitta]

Hi @TomasHubelbauer,

did @laurentpayot answer your question or do you require more support?

Thanks!

[TomasHubelbauer]

@DellaBitta Sorry, but as you can read, this idea while good in general, doesn't apply to the JS SDK :D So no, it is not really applicable to this problem… This is a feature request for the JS SDK to be able to pass it the configuration though its API without having to whip up stuff for that as its consumer.

[DellaBitta]

Ok, great, thanks for the quick response!

[TomasHubelbauer]

My pleasure! Thanks for considering this issue for triage 🤘

[laurentpayot]

@TomasHubelbauer also note that you can communicate between your main thread and workers with BroadcastChannel (simple way) or MessageChannel (more complex but safer as it queues unread messages).