ADR-005: ESLint Configuration Abstraction

• Status: accepted
• Date: 2025-01-26

Context and Problem Statement

The ESLint configuration was directly using @antfu/eslint-config in the eslint.config.js file. To make the package more useful for consumers and provide a cleaner API, we needed to abstract the ESLint configuration into a reusable function that could be imported and customized.

Decision Drivers

• Need to provide reusable ESLint configuration for consumers
• Desire to abstract antfu implementation details
• Requirement for easy customization and extension
• Need for consistent configuration across related projects
• Desire to provide a clean, simple API
• Need to support merging of custom options with defaults

Considered Options

• Keep direct antfu usage in eslint.config.js
• Create wrapper function with basic options
• Create abstraction with defu merging capabilities
• Create separate ESLint configuration package

Decision Outcome

Chosen option: "Create abstraction with defu merging capabilities", because it provides a clean API while allowing full customization through object merging.

Positive Consequences

• Clean, abstracted API for consumers
• Easy customization through object merging
• Hides antfu implementation details
• Consistent base configuration across projects
• Flexible extension capabilities
• Simple function-based API

Negative Consequences

• Additional dependency (defu)
• Slightly more complex internal structure
• Need to maintain abstraction layer

Implementation Details

• Abstraction file: eslint.js with createEslintConfig(options) function
• Dependency: defu for object merging
• Package export: "./eslint": "./eslint.js"
• Default configuration: TypeScript, Node.js, standard ignores
• Merging: Custom options override defaults using defu
• API: Simple function call with optional parameter

Usage Examples

Basic usage:

import createEslintConfig from '@relational-fabric/canon/eslint'

export default createEslintConfig()

With custom options:

import createEslintConfig from '@relational-fabric/canon/eslint'

export default createEslintConfig({
  ignores: ['custom-ignore'],
  rules: {
    'no-console': 'warn',
  },
})

For the package:

// eslint.config.js
import createEslintConfig from './eslint.js'

export default createEslintConfig()

Links

• defu - Object Merging Library
• @antfu/eslint-config