I don't see service worker activity in Brave

[misha-erm]

Hello 👋🏻

I'm using Brave browser and I can't see any requests handled by MSW in Network tab and no service workers in Application tab.

Is it expected?

[kettanaito]

Hey, @MikeYermolayev.

That seems like an issue. I'm testing the library in Brave and can see requests being handled in the Network, as well as the worker active in the "Application" tab.

• What version of Brave are you running?
• What version of MSW are you running?
• Can you see the orange "[MSW] Mocking enabled." message in the console? (if not, it's likely you're not calling worker.start()).
• Can you please share your setup?

[misha-erm]

Seems like problem appears only in local environment. On demo account it can be observed in dev tools as expected

• Version 1.30.87 Chromium: 94.0.4606.71 (Official Build) (x86_64)
• https://pkg.csb.dev/mswjs/msw/commit/f69b09c6/msw (because of Cannot access response body after request is intercepted by MSW #905 )
• It starts in fallback mode [MSW] Mocking enabled (fallback mode).
• I suppose the problem is that we do not use localhost or 127.0.0.1. We use hostname with http e.g. http://local.product.io:8000

[kettanaito]

You don't see the worker because MSW runs in a fallback mode in your case. The fallback mode is designed for environments that:

• Don't support Service Workers;
• Cannot run Service Workers (i.e. running from a local file://).

Neither seems to be the case for you.

You can check rather quickly what triggers a fallback mode for you. Here's the condition that enables the fallback mode:

msw/src/setupWorker/setupWorker.ts

Lines 155 to 156 in 11bb244

	useFallbackMode:
	!('serviceWorker' in navigator) || location.protocol === 'file:',

One of these statements is true.

[misha-erm]

hm. Seems like serviceWorker is missing in navigator object.

I think this might be the answer https://stackoverflow.com/a/54934302/4280642 . Will check and come back later

[kettanaito]

Oh, my bad, I should've pointed this earlier.

If you're running on a custom host, it should be served via HTTPS and/or marked as secure in your browser (ideally, both). Otherwise, Service Workers won't work, treating your environment as unsafe.

If you decide to go the local HTTPS route, we have the guide written on that.

[misha-erm]

Adding my domain to chrome://flags/#unsafely-treat-insecure-origin-as-secure helped with the issue. Can see service worker in local environment too.

https://stackoverflow.com/a/54934302/4280642