Dev service worker on Firefox is not working

[fkrauthan]

I've configured the service worker to use strategies: "injectManifest", and created the minimal service worker code required. My dev section looks as follow:

			devOptions: {
				enabled: true,
				type: "module",
			},

However when running my sveltekit app in dev mode (pnpm run dev) and opening the page on Firefox I get a SW registration error TypeError: ServiceWorker script at http://localhost:5173/dev-sw.js?dev-sw for scope http://localhost:5173/ threw an exception during script evaluation. [PWA.svelte:23:18](http://localhost:5173/src/lib/components/PWA.svelte) error (without any additonal errors displayed in the console).

Opening the same page in for example Chrome registers the service worker correctly.

You can use this repository https://github.com/fkrauthan/sveltekit-pwa-issue to see this issue yourself.

[userquin]

You cannot use custom sw with type module in Firefox, it is not supported.

[fkrauthan]

Hmm but changing type to classic produces the same error?

[userquin]

Because cannot use import statements, the custom sw in dev is "compiled" via esbuild just removing the ts annotations:

• https://caniuse.com/?search=service%20worker
• https://caniuse.com/mdn-javascript_statements_import_service_worker_support

Check the source code in the network or source tab.

[fkrauthan]

Ah so in general dev mode for service workers does not work right now for firefox. Might be worth pointing out in the docs (as it only calls out that type module is only supported on chromium.

[userquin]

You can write your custom service worker using importScripts, it should work.

[userquin]

Ah so in general dev mode for service workers does not work right now for firefox. Might be worth pointing out in the docs (as it only calls out that type module is only supported on chromium.

https://vite-pwa-org.netlify.app/guide/development.html#injectmanifest-strategy

[fkrauthan]

Yeah to me that reads as I can use type module on chrome (especially since the box just below it talks about that classic is used for prod builds all the time and works on all browsers), and I can use classic on all browsers.