Allow for browserslist environment variables

[GreenGremlin]

Browserslist allows for setting browserslist config using environment variables, but CRA still prompts for setting browserslist config when it is already configured for the environment.

For example, running this currently results in CRA improperly detecting that browserslist is not configured, even though it is.

BROWSERSLIST="> 5%" npm run build

[GreenGremlin]

It looks like the build is now passing for other MRs, can someone please re-run CI on this MR?

[GreenGremlin]

It looks like the build is now passing for other MRs, can someone please re-run CI on this MR?

Never mind, I just pushed an amended commit.

[mrmckeb]

@GreenGremlin We've had some problems with out CR, sorry that you had to push to get your PR (😉) to pass.

[mrmckeb]

This looks good, can you share the documentation on this? I couldn't find it on their repo.

[GreenGremlin]

This looks good, can you share the documentation on this? I couldn't find it on their repo.

Unfortunately, just like findConfig there doesn't appear to be documentation on loadConfig. You can see from the loadConfig implementation that, unlike findConfig which just returns the path to the config, it returns the actual config. The primary difference here being that it also checks process.env.BROWSERSLIST and process.env.BROWSERSLIST_CONFIG, which findConfig doesn't account for.

[mrmckeb]

I had a look there, thanks! I've tagged this for the next minor.

[ianschmitz]

It's interesting that we're setting this in our e2e tests. I imagine it must not be doing anything?

create-react-app/tasks/e2e-kitchensink.sh

Line 107 in ac93f31

export BROWSERSLIST='ie 9'

[GreenGremlin]

It's interesting that we're setting this in our e2e tests. I imagine it must not be doing anything?

create-react-app/tasks/e2e-kitchensink.sh

Line 107 in ac93f31

export BROWSERSLIST='ie 9'

The environment variables work for everything but the check for browserslist config that determines wether we should prompt to add it. Also, if the e2e tests are not run interactively, we may just skip the prompt entirely.

[ianschmitz]

Thanks @GreenGremlin!