Next.js 15 ESLint v9

eslint.config.js

/* eslint-disable import-x/no-named-as-default-member */

import comments from '@eslint-community/eslint-plugin-eslint-comments/configs'
import react from '@eslint-react/eslint-plugin'
import { FlatCompat } from '@eslint/eslintrc'
import js from '@eslint/js'
import prettierConfig from 'eslint-config-prettier'
import eslintPluginImportX from 'eslint-plugin-import-x'
import regexPlugin from 'eslint-plugin-regexp'
import security from 'eslint-plugin-security'
import globals from 'globals'
import tseslint from 'typescript-eslint'

import tailwind from 'eslint-plugin-tailwindcss'

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

const config = tseslint.config(
  {
    ignores: ['.next', 'node_modules'],
  },
  // Base
  js.configs.recommended,
  ...tseslint.configs.strictTypeChecked,
  ...tseslint.configs.stylisticTypeChecked,
  eslintPluginImportX.flatConfigs.recommended,
  eslintPluginImportX.flatConfigs.typescript,
  comments.recommended,
  regexPlugin.configs['flat/recommended'],
  security.configs.recommended,

  // Next.js / React
  ...compat.extends('plugin:@next/next/recommended'),
  ...compat.extends('plugin:react-hooks/recommended'),
  ...compat.plugins('react-compiler'),
  react.configs['recommended-type-checked'],

  // Tailwind
  ...tailwind.configs['flat/recommended'],

  {
    linterOptions: {
      reportUnusedDisableDirectives: true,
    },
    languageOptions: {
      ecmaVersion: 'latest',
      sourceType: 'module',
      parserOptions: {
        projectService: true,
        tsconfigRootDir: import.meta.dirname,
        ecmaFeatures: {
          jsx: true,
        },
      },
      globals: {
        ...globals.browser,
        ...globals.node,
      },
    },
    settings: {
      tailwindcss: {
        callees: ['classnames', 'clsx', 'ctl', 'cn', 'cva'],
      },
    },
    rules: {
      '@typescript-eslint/no-unused-vars': [
        'error',
        { argsIgnorePattern: '^_', varsIgnorePattern: '^_' },
      ],

      '@typescript-eslint/consistent-type-imports': [
        'warn',
        { prefer: 'type-imports', fixStyle: 'separate-type-imports' },
      ],

      '@typescript-eslint/no-misused-promises': [
        'error',
        { checksVoidReturn: { attributes: false } },
      ],

      '@typescript-eslint/no-unnecessary-condition': [
        'error',
        {
          allowConstantLoopConditions: true,
        },
      ],

      '@typescript-eslint/consistent-type-exports': [
        'error',
        { fixMixedExportsWithInlineTypeSpecifier: true },
      ],

      'import-x/no-unresolved': ['error', { ignore: ['geist'] }],
      'react-compiler/react-compiler': 'error',
    },
  },

  {
    files: ['**/*.cjs', '**/*.cts'],
    languageOptions: {
      sourceType: 'commonjs',
    },
  },

  prettierConfig,
)

export default config

/* eslint-enable import-x/no-named-as-default-member */

eslint.d.ts

declare module '@eslint-community/eslint-plugin-eslint-comments/configs' {
  import type { Linter } from 'eslint'

  export const recommended: {
    rules: Linter.RulesRecord
  }
}

package.json

{
   "devDependencies": {
    "@eslint-community/eslint-plugin-eslint-comments": "^4.4.1",
    "@eslint-react/eslint-plugin": "^1.15.2",
    "@eslint/eslintrc": "^3.1.0",
    "@eslint/js": "^9.13.0",
    "@next/eslint-plugin-next": "^15.0.2",
    "@types/eslint-config-prettier": "^6.11.3",
    "@types/eslint-plugin-security": "^3.0.0",
    "@types/eslint-plugin-tailwindcss": "^3.17.0",
    "@types/eslint__eslintrc": "^2.1.2",
    "@types/eslint__js": "^8.42.3",
    "eslint": "^9.13.0",
    "eslint-config-prettier": "^9.1.0",
    "eslint-import-resolver-typescript": "^3.6.3",
    "eslint-plugin-import-x": "^4.3.1",
    "eslint-plugin-react-compiler": "19.0.0-beta-6fc168f-20241025",
    "eslint-plugin-react-hooks": "^5.0.0",
    "eslint-plugin-regexp": "^2.6.0",
    "eslint-plugin-security": "^3.0.1",
    "eslint-plugin-tailwindcss": "^3.17.5",
    "globals": "^15.11.0",
    "typescript": "^5.6.3",
    "typescript-eslint": "^8.12.2"
  }
}