ServiceWorker not built in 4.x (next)

Describe the bug

./build/service-worker.js is no longer generated at all (and there are no error messages) with the latest versions of CRA (4.x) using @next.

Did you try recovering your dependencies?

Yes.

Which terms did you search for in User Guide?

N/A

Environment

(paste the output of the command here.)

Steps to reproduce

(Write your steps here:)

1. npx create-react-app test
2. cd test
3. npm install --save react-scripts@next
4. npm run build
5. ls -la ./build

Expected behavior

./build/service-worker.js should be present.

Actual behavior

The file is missing. This causes a problem with apps which are upgrading from prior CRA versions, as they continue to reference the cached service worker (so the web app continues to cache old assets).

Reproducible demo

Just run the commands above.

[zaneclaes]

It would be nice if there were a decent upgrade path, here. Or just a documented one.

For those upgrading to 4.x in an existing project, this is an extremely confusing change. In my case, it transparently broke my application due to a sudden lack of service workers. As others have noted, the upgrade docs are woefully insufficient.

In any case, my “fix” was to create a dummy app:

npx create-react-app my-app --template cra-template-pwa-typescript

And copy over the relevant code:

• reportWebVitals.ts
• service-worker.ts
• serviceWorkerRegistration.ts

As well as the initialization code in index.tsx.

[kivervinicius]

I believe that there are more complaints about forcing a service worker by default than not, but it is extremely simple to continue using serviceWorker.

npx create-react-app my-app --template cra-template-pwa