Bevry's ESLint configuration is an intelligent, self-configuring system that automatically analyzes your project and adapts ESLint configuration accordingly. It performs comprehensive project analysis to detect your development environment and applies the optimal ESLint setup.

🚀 For the ultimate zero-configuration experience: Use Boundation - Bevry's automatic scaffolding and upgrading tool. When your project is scaffolded and managed by Boundation, nearly everything (including ESLint, TypeScript, testing, documentation, CI/CD, and more) is automatically configured and maintained using Bevry's battle-tested best practices. Simply run npx boundation in your project directory for complete project setup and ongoing maintenance.

• Boundation Ecosystem (optional): Complete automation via interactive Q&A system. When using Boundation, virtually all project metadata (editions, dependencies, keywords, browser fields, TypeScript/Babel/React setup, etc.) is automatically injected and managed, eliminating the need for manual configuration of the elements below.
• Editions Integration (optional): When present, analyzes your package.json editions to extract syntax, module system, and target environment information
• Dependency Detection: Scans dependencies and devDependencies to automatically enable relevant plugins and configurations
• Package.json Analysis: Examines keywords, browser field, and other metadata to determine your project's target environment
• ECMAScript Version Intelligence: Dynamically detects and configures for your specific ECMAScript target (ES5, ES2015, ES2017, ES2020, ES2021+)
  • Automatically disables incompatible rules for older targets
  • Configures appropriate globals and language features
  • Adjusts rule severity based on target capabilities

• ESLint Foundation: Extends ESLint's recommended configuration from @eslint/js as the baseline for all linting rules.
• Module System Detection: Automatically configures for ES modules or CommonJS based on your project structure
  • Enables eslint-plugin-import with appropriate module validation
  • Configures TypeScript-aware import rules when applicable
• Environment-Specific Setup: Intelligently configures globals and rules for detected environments:
  • Node.js: Configures eslint-plugin-n with module-aware or script-aware settings
  • Browser: Applies browser globals and environment-specific rules
  • Web Workers: Configures worker and service worker globals
• Framework Integration: Automatically detects and configures framework-specific linting:
  • React: Enables eslint-plugin-react with auto-detected React version and eslint-plugin-react-hooks
  • JSX: Configures JSX parsing and JSX-runtime rules when detected
• Language Support: Comprehensive language tooling integration:
  • TypeScript: Uses typescript-eslint with strict configuration, disables conflicting JavaScript rules
  • Babel: Integrates @babel/eslint-parser and @babel/eslint-plugin when detected
• Documentation Standards: Automatic JSDoc validation with eslint-plugin-jsdoc, TypeScript-aware when applicable
• Code Formatting: Intelligent Prettier integration via eslint-config-prettier with comprehensive stylistic rule management:
  • Prettier-Compatible Rules: Special rules that can coexist with Prettier (marked as specialRule rather than disabled)
  • Legacy Stylistic Rules: Non-Prettier rules managed by ESLint Stylistic for comprehensive code consistency
  • Smart Conflict Resolution: Automatic detection and resolution of formatting conflicts between ESLint and Prettier

The configuration includes 120+ carefully curated ESLint rules designed to enforce best practices and coding conventions battle-tested by Bevry across 200+ packages and 20 years of JavaScript development.

Zero-Conflict Architecture: Takes great care to ensure zero conflicts between custom rules and plugin configurations. Each rule override is intentional and documented, preventing configurations from inadvertently disabling important plugin-provided rules.

Battle-Tested Standards: These conventions have evolved through maintaining hundreds of open source projects, from simple utilities to complex applications, ensuring they work reliably across diverse JavaScript environments and use cases.

All rules automatically adapt based on your detected environment, target ECMAScript version, and enabled features.

For your test.ts you probably want to add the following:

/* eslint-disable @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-function-type, @typescript-eslint/no-empty-object-type, @typescript-eslint/no-unsafe-argument -- we are writing tests, we have to test type-unsafe inputs */

• 🚀 Zero Configuration: Works out-of-the-box with intelligent project detection
• 📦 Dependency-Free: No need to install or manage individual ESLint plugins
• 🔧 Self-Maintaining: Configuration updates automatically with your project changes
• ⚡ Performance Optimized: Only loads and configures plugins you actually need
• 🛡️ Battle-Tested: Used across Bevry's ecosystem of 200+ open source projects

Use boundation to automate installation and maintenance, making the rest of this usage section unnecessary.

Otherwise, to proceed and maintain manually, first install it and ESLint:

npm install --save-dev eslint eslint-config-bevry

💡 Zero Plugin Management: With eslint-config-bevry, there's no need to manually install or configure any ESLint plugins (eslint-plugin-react, typescript-eslint, eslint-plugin-import, etc.). The configuration automatically includes and configures all necessary plugins based on your project's detected features, saving you from dependency management complexity.

Then add eslint.config.js file to your project root:

import { defineConfig } from 'eslint/config'
import eslintBevry from 'eslint-config-bevry'
export default defineConfig(eslintBevry)

eslint-config-bevry supports customization through your package.json or programmatically:

Default Files: When no files are specified, eslint-config-bevry automatically includes:

• If Editions are detected: {sourceEdition.directory}/**/*.{js,cjs,mjs,jsx,mjsx,ts,cts,mts,tsx,mtsx}
• Otherwise: **/*.{js,cjs,mjs,jsx,mjsx,ts,cts,mts,tsx,mtsx}

Default Ignores: Always includes these patterns (your custom ignores are appended):

• **/*.d.ts - TypeScript declaration files
• **/vendor/ - Third-party vendor directories
• **/node_modules/ - Node.js dependencies

Via package.json:

{
    "eslintConfig": {
        "files": [
            // Replaces the configuration from `eslint-config-bevry`
            "source/**/*.{js,ts}"
        ],
        "ignores": [
            // Appends to the configuration from `eslint-config-bevry`
            "dist/",
            "*.config.js"
        ],
        "rules": {
            // Overrides the configuration from `eslint-config-bevry`
            "no-console": "off"
        }
    }
}

Programmatic customization:

import { defineConfig } from 'eslint/config'
import eslintBevry from 'eslint-config-bevry'
export default defineConfig({
    extends: [eslintBevry],
    files: [
        // Replaces the configuration from `eslint-config-bevry`
        'source/**/*.{js,ts}',
    ],
    ignores: [
        // Appends to the configuration from `eslint-config-bevry`
        'dist/',
        '*.config.js',
    ],
    rules: {
        // Overrides the configuration from `eslint-config-bevry`
        'no-console': 'off',
    },
})

Use ESLint as normal:

npx eslint --fix

To see, inspect, and debug the resultant configuration:

npx eslint --inspect-config

To validate your configuration is working correctly:

# Check specific files
npx eslint source/index.js --max-warnings 0

# See what files ESLint will process
npx eslint --dry-run

🔍 Troubleshooting: If you encounter unexpected behavior, the configuration adapts based on your package.json dependencies and metadata. Check that your project's dependencies, devDependencies, keywords, and editions accurately reflect your project setup.

Discover the release history by heading on over to the HISTORY.md file.

Discover how to contribute via the CONTRIBUTING.md file.

• Benjamin Lupton — Accelerating collaborative wisdom.

• Benjamin Lupton — Accelerating collaborative wisdom.

• Benjamin Lupton — view contributions
• Michael Duane Mooring — view contributions
• Rob Loach — view contributions

• Andrew Nesbitt — Working on mapping the world of open source software @ecosyste-ms and empowering developers with @octobox
• Divinci ™ — A more comfortable AI conversation experience, with friends! 🤖🖤
• Mr. Henry
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• GitHub
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• WriterJohnBuck

Unless stated otherwise all works are:

• Copyright © Benjamin Lupton

and licensed under:

• Artistic License 2.0