Improve examples folder

[ahnpnl]

Summary

See individual commits

Test plan

Green CI

Does this PR introduce a breaking change?

• Yes
• No

Other information

N.A.

[coveralls]

Pull Request Test Coverage Report for Build 4596657275

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.009%) to 95.842%

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Totals
Change from base Build 4595719534:	0.009%
Covered Lines:	4055
Relevant Lines:	4154

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💛 - Coveralls

[mike-lischke]

Very nice! I wonder why you now spread the preset in the config. For me it works fine to set the preset field and have the transform field set to transform ts with ESM.

[ahnpnl]

The purpose is moving away from using preset key to avoid conflicting when using together with transform. Even though we have put a warning in documentation but still many users often run into that mistake.

Making example repos config to be clearer is the first step.

[mike-lischke]

But isn't the preset key the main configuration switch in Jest? Somehow that seems to be counter productive. Wouldn't it be better to check if both are used and print an error in the terminal, instead?

[ahnpnl]

That would be the 2nd step.

[ahnpnl]

Ping @kulshekhar