If I shouldn't serve mockServiceWorker.js in production, then why "public" directory?

[silvenon]

The site doesn't seem to mention anything about this warning in the script:

Please do NOT serve this file on production.

All examples include copying the script to "public", but this location will make it to production. Or is serving https://my-site.com/mockServiceWorker.js without starting it harmless, and not what the script is warning me about?

If I'm indeed supposed to keep it away from production, and the script will be installed in "public" upon installing msw, I guess the only way is to delete that script after installing dependencies?

[kettanaito]

Hi, @silvenon.

We are going a bit too harsh on the warning so to make it clear you don't use MSW in production. In practice, you are right, just placing the worker script in a public directory will normally mean that it's also there in production. I trust it to your build setup to remove it when needed, e.g.

  - name: build
    run: npm run build && rm ./public/mockServiceWorker.js

Maybe we should be more explicit about this. The problem with mentioning this is that there are multiple ways to solve this and, ultimately, you should know best. So it's hard to recommend "one size fits all" approach.

Serving the worker script in production without registering it does nothing. It doesn't affect your site and your app must never load it (that is a hard must).

[kettanaito]

Also seems a nice way to check if someone is using MSW: https://github.com/mockServiceWorker.js. Huh.

[silvenon]

The example with removing it from public is sending me mixed signals, but my understanding from what you said, and from GitHub's own serving of MSW, is that it's ok to serve the file as long as I'm not mocking in production, i.e. as long as I'm not USING the file in production.

Btw, the GitHub example made me chuckle 😄

[kettanaito]

Nobody's paying any price for having it there so I see little reason to emphasize on it. Besides, there are companies that are using MSW but don't serve it in production. The way you serve frontend assets is, generally, extremely project-dependent.

Have fun!