eslint-prettier-config

ESLint & Prettier Configuration

Setup consistent code quality and formatting with ESLint and Prettier.

Core Workflow

1. Install dependencies: ESLint, Prettier, plugins
2. Configure ESLint: Rules and extends
3. Configure Prettier: Formatting options
4. Integrate tools: ESLint + Prettier
5. Setup scripts: Lint and format commands
6. Add hooks: Pre-commit validation

ESLint Flat Config (v9+)

// eslint.config.mjs
import js from '@eslint/js';
import typescript from '@typescript-eslint/eslint-plugin';
import tsParser from '@typescript-eslint/parser';
import react from 'eslint-plugin-react';
import reactHooks from 'eslint-plugin-react-hooks';
import reactRefresh from 'eslint-plugin-react-refresh';
import importPlugin from 'eslint-plugin-import';
import prettier from 'eslint-config-prettier';

export default [
  // Ignore patterns
  {
    ignores: [
      '**/node_modules/**',
      '**/dist/**',
      '**/build/**',
      '**/.next/**',
      '**/coverage/**',
      '**/*.config.js',
      '**/*.config.mjs',
    ],
  },

  // Base JavaScript config
  js.configs.recommended,

  // TypeScript files
  {
    files: ['**/*.ts', '**/*.tsx'],
    languageOptions: {
      parser: tsParser,
      parserOptions: {
        ecmaVersion: 'latest',
        sourceType: 'module',
        ecmaFeatures: {
          jsx: true,
        },
        project: './tsconfig.json',
      },
    },
    plugins: {
      '@typescript-eslint': typescript,
      'import': importPlugin,
    },
    rules: {
      // TypeScript rules
      ...typescript.configs.recommended.rules,
      '@typescript-eslint/no-unused-vars': ['error', {
        argsIgnorePattern: '^_',
        varsIgnorePattern: '^_',
      }],
      '@typescript-eslint/no-explicit-any': 'warn',
      '@typescript-eslint/explicit-function-return-type': 'off',
      '@typescript-eslint/explicit-module-boundary-types': 'off',
      '@typescript-eslint/no-non-null-assertion': 'warn',
      '@typescript-eslint/consistent-type-imports': ['error', {
        prefer: 'type-imports',
        fixStyle: 'inline-type-imports',
      }],

      // Import rules
      'import/order': ['error', {
        groups: [
          'builtin',
          'external',
          'internal',
          ['parent', 'sibling'],
          'index',
          'type',
        ],
        'newlines-between': 'always',
        alphabetize: { order: 'asc', caseInsensitive: true },
      }],
      'import/no-duplicates': 'error',
    },
  },

  // React files
  {
    files: ['**/*.tsx', '**/*.jsx'],
    plugins: {
      'react': react,
      'react-hooks': reactHooks,
      'react-refresh': reactRefresh,
    },
    settings: {
      react: {
        version: 'detect',
      },
    },
    rules: {
      ...react.configs.recommended.rules,
      ...reactHooks.configs.recommended.rules,
      'react/react-in-jsx-scope': 'off',
      'react/prop-types': 'off',
      'react/jsx-uses-react': 'off',
      'react/jsx-no-target-blank': 'error',
      'react/self-closing-comp': 'error',
      'react/jsx-curly-brace-presence': ['error', {
        props: 'never',
        children: 'never',
      }],
      'react-hooks/rules-of-hooks': 'error',
      'react-hooks/exhaustive-deps': 'warn',
      'react-refresh/only-export-components': ['warn', {
        allowConstantExport: true,
      }],
    },
  },

  // Test files
  {
    files: ['**/*.test.ts', '**/*.test.tsx', '**/*.spec.ts', '**/*.spec.tsx'],
    rules: {
      '@typescript-eslint/no-explicit-any': 'off',
      '@typescript-eslint/no-non-null-assertion': 'off',
    },
  },

  // Disable rules that conflict with Prettier
  prettier,
];