eslint-find-rules

5.0.0 verified Sat Apr 25 auth: no javascript

ESLint utility (v5.0.0, released Dec 2024) that finds built-in and plugin rules missing from your custom ESLint config. Supports both legacy (.eslintrc) and flat config (eslint.config.js). Offers options to list all available rules, current rules, deprecated rules, plugin-specific rules, and unused rules. Actively maintained with support for ESLint v8.57+ and v9.18+. Compatible with Node >=18.20. Differentiators: CLI-first, zero-config for simple use, explicit flag for flat config, and options to include/exclude deprecated or core rules.

Common errors

error Error: Cannot find module 'eslint' ↓

cause eslint not installed or not in node_modules

fix

npm install eslint --save-dev

error Error: ESLint configuration is invalid ↓

cause Provided config file has syntax errors or is not a valid ESLint config

fix

Check the config file for errors, ensure it exports a valid config object

error Error: Unknown option '--flatConfig' ↓

cause Using an older version (<4.2.0) of eslint-find-rules that doesn't support flat config

fix

Upgrade eslint-find-rules to v4.2.0+ with npm install eslint-find-rules@latest

error Error: Process exited with code 1 (no error message) ↓

cause Deprecated or unused rules found; tool exits with non-zero by default

fix

Add -n/--no-error flag if you want to suppress exit code

Warnings

breaking Requires Node >= 18.20 and ESLint >= 8.57.1 ↓

fix Upgrade Node to 18.20+ and ESLint to 8.57.1+ or 9.18+

deprecated Support for ESLint < 8.57.1 dropped in v5 ↓

fix Pin to eslint-find-rules@4.x if using older ESLint

breaking Support for ESLint < 7 dropped in v4.0.0 ↓

fix Use ESLint >= 7 or stick to v3.x

gotcha Using globally installed eslint-find-rules will fail if ESLint and plugins are not also global ↓

fix Install eslint-find-rules as a devDependency and run via npm script

gotcha By default, deprecated rules are omitted from --all-available, --plugin, and --unused output ↓

fix Add --include deprecated or -i deprecated flag to include deprecated rules

breaking Flat config support requires --flatConfig flag; without it, legacy mode is assumed ↓

fix Add --flatConfig to the command when using eslint.config.js

Install

npm install eslint-find-rules

yarn add eslint-find-rules

pnpm add eslint-find-rules

Imports

cli
```
npx eslint-find-rules --unused .eslintrc.js
```
CLI tool, not a library. Use as npm script or npx.
programmatic API
```
const { findRules } = require('eslint-find-rules');
```
Programmatic API is available but undocumented; CLI is the primary interface.
module
```
import { findRules } from 'eslint-find-rules';
```
ESM import works if package is used in a module context (package.json type: module).

Quickstart

Shows how to add eslint-find-rules as an npm script to detect unused or missing rules in your ESLint config.

// package.json
{
  "scripts": {
    "find-unused": "eslint-find-rules --unused .eslintrc.js"
  },
  "devDependencies": {
    "eslint-find-rules": "^5.0.0"
  }
}

// Then run:
// npm run find-unused

// For flat config:
// eslint-find-rules --unused eslint.config.js --flatConfig

// All available options:
// eslint-find-rules --all-available .eslintrc.js
// eslint-find-rules --current .eslintrc.js
// eslint-find-rules --deprecated .eslintrc.js
// eslint-find-rules --plugin .eslintrc.js