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Adding ignore folders to flat file eslint config

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joostschuur posted this in #help-forum
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joostschuurOP
I'm trying to get eslint to ignore an additional folder (or just what's in .gitignore), but can't seem to get this to work with the new flat filesystem format (I'm on Next.js 15.3) and at build time.

next lint isn't processing files in tmp (which is also in .gitignore), but next build returns a linting error from a .ts file in tmp which I'm trying to ignore.

It looks like I'm trying to combine these two approaches, and I'm not sure if I'm doing this right:

https://nextjs.org/docs/app/api-reference/config/eslint#additional-configurations
https://eslint.org/docs/latest/use/configure/ignore#including-gitignore-files

3 Replies

joostschuurOP
import { FlatCompat } from '@eslint/eslintrc';
import { defineConfig } from 'eslint/config';
import { fileURLToPath } from 'url';

const gitignorePath = fileURLToPath(new URL('.gitignore', import.meta.url));

const compat = new FlatCompat({
  baseDirectory: import.meta.dirname,
});

const eslintConfig = defineConfig([
  includeIgnoreFile(gitignorePath, compat),
  {
    linterOptions: {
      reportUnusedDisableDirectives: true,
    },
  },
  // Custom rules would go here
  {
    rules: {},
  },
  ...compat.config({
    extends: ['next/core-web-vitals', 'next/typescript'],
  }),
]);

export default eslintConfig;
joostschuurOP
using dirs in next.config.ts doesn't seem to work either. eslint: { dirs: ['src'] } still gives me the same linting error from tmp which is a sibling directory.

https://nextjs.org/docs/app/api-reference/config/eslint#linting-custom-directories-and-files
joostschuurOP
Well, it looks like the solution is to put the additional folder into tsconfig.json's exclude folder list.

Not fully intuitive, but I guess it's because using @typescript/eslint under the hood? I don't think the docs were helpful in pointing this out 😦