Directory Configuration

Advanced configuration building for specific directories, supporting both file paths and file:// URLs. Handles config reading, path resolution, and pattern building for monorepo structures.

Capabilities

matchToFlatDir Function

Builds ESLint flat config for a specific directory path, automatically reading configuration files and adjusting file patterns with directory prefixes.

/**
 * Builds ESLint flat config for a specific directory path
 * @param {string|URL} cwd - Current working directory or file URL
 * @param {string} path - Relative path to directory
 * @param {Object} [config] - Optional existing config object, reads from directory if not provided
 * @param {Object} [overrides] - Optional override functions for dependency injection
 * @returns {Promise<Array<Object>>} Promise resolving to array of ESLint flat config objects
 */
async function matchToFlatDir(cwd, path, config, overrides);

Parameters:

• cwd (string|URL): Current working directory or file:// URL (supports import.meta.url)
• path (string): Relative path to the directory containing ESLint configuration
• config (Object, optional): Existing configuration object. If not provided, reads from directory
• overrides (Object, optional): Override functions for dependency injection (currently no public override options available)

Returns: Promise resolving to array of ESLint flat config objects with properly prefixed file patterns.

Usage Examples:

With File Path:

const { matchToFlatDir } = require('@putout/eslint-flat');

// Using __dirname (CommonJS)
const config = await matchToFlatDir(__dirname, './packages/putout');

// The function will:
// 1. Read eslint config from ./packages/putout directory
// 2. Prefix all file patterns with **/packages/putout/
// 3. Return flat config array

With File URL (ESM):

import { matchToFlatDir } from '@putout/eslint-flat';

// Using import.meta.url (ESM)
const config = await matchToFlatDir(import.meta.url, './packages/putout');

With Custom Configuration:

const { matchToFlatDir } = require('@putout/eslint-flat');

// Provide config directly instead of reading from directory
const customConfig = {
  match: {
    'bin/*.js': {
      'n/hashbang': 'off',
    },
    'lib/**/*.js': {
      'complexity': ['error', 10],
    },
  },
};

const result = await matchToFlatDir(__dirname, './my-package', customConfig);
// Result will have patterns like:
// - files: ['**/my-package/bin/*.js']
// - files: ['**/my-package/lib/**/*.js']

In Monorepo ESLint Config:

const { safeAlign } = require('eslint-plugin-putout/config');
const { matchToFlatDir } = require('@putout/eslint-flat');

module.exports = [
  ...safeAlign,
  // Include configuration from specific package
  ...await matchToFlatDir(__dirname, './packages/putout'),
  ...await matchToFlatDir(__dirname, './packages/eslint-flat'),
];

Configuration File Resolution

The function automatically tries to read ESLint configuration in this order:

1. Modern flat config files:

   • eslint.config.js
   • eslint.config.cjs
   • eslint.config.mjs

2. Legacy configuration:

   • .eslintrc.json (converted using ESLint's FlatCompat)

Configuration Formats

Match Object Format (Simplified): If the config exports a match property, it uses the simplified object format:

// In ./packages/my-package/eslint.config.js
module.exports = {
  match: {
    'src/*.js': {
      'no-console': 'warn',
    },
    'test/*.js': {
      'no-console': 'off',
    },
  },
};

Standard Flat Config Format: If no match property, processes as standard ESLint flat config:

// In ./packages/my-package/eslint.config.js
module.exports = [
  {
    files: ['src/*.js'],
    rules: {
      'no-console': 'warn',
    },
  },
  {
    files: ['test/*.js'],
    rules: {
      'no-console': 'off',
    },
    ignores: ['test/fixtures/**'],
  },
];

Path Handling

File Pattern Processing:

• Automatically prefixes file patterns with **/directory-path/
• Handles both simple patterns and complex glob patterns
• Preserves function-based file patterns without modification

Ignore Pattern Processing:

• Processes ignores arrays by prefixing with directory path
• Preserves function-based ignore patterns
• Only adds ignores property if patterns exist

URL Support:

• Supports both regular directory paths and file:// URLs
• Automatically converts file:// URLs to file system paths
• Useful for ESM modules using import.meta.url

Error Handling

• Returns empty array [] if no configuration files are found
• Gracefully handles missing directories
• Uses try-catch internally to prevent errors from propagating
• Supports dependency injection via overrides for testing