can't handle request for shared workers

[njoel24]

Prerequisites

• I confirm my issue is not in the opened issues
• I confirm the Frequently Asked Questions didn't contain the answer to my issue

Environment check

• I'm using the latest msw version
• I'm using Node.js version 14 or higher

Browsers

Chromium (Chrome, Brave, etc.)

Reproduction repository

not available

Reproduction steps

When trying to request a shared worker, the clientId attached to fetch event object is an empty string.

That causes the following line to break under mockServiceWorker.js in resolveMainClient function:
if(client.frameType === 'top-level')

I managed to make it work currently by checking for client like the following:
if(client && client.frameType === 'top-level')

With that I am able to work with shared worker.

Do you have any ideas why that happens?

msw version: 0.44.2

Thanks

Current behavior

the msw fails handling the request

Expected behavior

msw should handle the request.

[kettanaito]

Hey, @njoel24.

Could you tell me more about your setup? It's really hard to advise anything without knowing what/how you're trying to do.

This condition is a part of the resolveMainClient logic that tries to look up the actual client that has registered the worker. Since you may have nested clients (i.e. a page embed via iframe), we need to find the top-level client, which is always your application that called worker.start(). It's that client with which the worker must communicate, that client is responsible for request resolution.

I don't have experience with shared workers. I'd be thankful if you contributed an integration test for that, which would reproduce the issue. Until then, I consider this issue closed for the lack of a reproduction scenario.

[njoel24]

Hey @kettanaito ,

thanks for your reply.

In the issue I described there are no iframes involved, it might be something related on how the shared worker requests the resource.

Yes, I will definitely create an integration test for that, so you will have more details.

[njoel24]

hey @kettanaito ,

I created an integration test for the issue: https://github.com/njoel24/integration-test-ms-shared-worker
Just clone, install, run 'npm run build' and run 'npm run start' and run the code on the browser.

Here what the error should be in console:

Please note that the handler has not been implemented and left as null because the error happens before.

Kindly let me know if you need any more information.
I would be more than happy to help.

[kettanaito]

Released: v0.48.0 🎉

This has been released in v0.48.0!

• 📄 Release notes
• 📦 npm package

Make sure to always update to the latest version (npm i msw@latest) to get the newest features and bug fixes.

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