Use flat config format

[jhnns]

https://eslint.org/blog/2022/08/new-config-system-part-2/

[jhnns]

Implementation has started on https://github.com/peerigon/eslint-config-peerigon/tree/eslint-9

There are a couple of plugins that don't have ESLint 9 support yet:

• eslint-plugin-import Support eslint v9 import-js/eslint-plugin-import#2948
• eslint-plugin-promise Support ESLint 9 and Flat config eslint-community/eslint-plugin-promise#449
• eslint-plugin-react ESLint v9 contains breaking API changes jsx-eslint/eslint-plugin-react#3699

(Also interesting: eslint/eslint#18391)

We don't necessarily have to wait for all of them because we might switch some dependencies (e.g. switching out eslint-plugin-promise with eslint-plugin-unicorn which also has some promise rules). However, I would definitely wait for eslint-plugin-react as there is not a good alternative afaik.

[karlhorky]

Hey @jhnns! 👋 It's possible to migrate now using the Compatibility Utilities, in case you want to try it out:

• https://x.com/karlhorky/status/1792500811307622631