eslint-plugin-ckeditor5-rules

15.0.0 verified Sat Apr 25 auth: no javascript

Official ESLint plugin used by the CKEditor 5 team for enforcing project-specific code style and linting rules. Current stable version is 15.0.0 (released as part of CKEditor 5 linters config). The plugin follows CKEditor 5's major/minor versioning policy, with breaking changes occurring in major releases. It provides rules for import validation, license headers, no-enum, module tag validation, changelog formatting, and more. Typically used via the eslint-config-ckeditor5 preset, but can be used standalone. Requires Node.js >=24.11.0. Differentiators: tightly coupled with CKEditor 5 development workflow; includes rules like `cross-package-imports`, `no-relative-imports`, and `allow-imports-only-from-main-package-entry-point` that enforce strict module boundaries.

Common errors

error Error: Cannot find module 'eslint-plugin-ckeditor5-rules' ↓

cause Package not installed or incorrect import path

fix

Run 'npm install --save-dev eslint-plugin-ckeditor5-rules' and verify the import is correct (ESM only)

error ESLint configuration error: ["ckeditor5-rules/no-relative-imports"] is not a valid rule ↓

cause Rule name not prefixed correctly in flat config

fix

Use 'ckeditor5-rules/no-relative-imports': 'error' (include the prefix)

error TypeError: ckeditor5Rules is not a function or object ↓

cause Using CommonJS require() on an ESM-only package

fix

Change to 'import ckeditor5Rules from 'eslint-plugin-ckeditor5-rules'' and ensure your project uses ESM

error Unsupported rule: ckeditor5-rules/ckeditor-imports ↓

cause Rule was removed in v14.0.0

fix

Use 'ckeditor5-rules/allow-imports-only-from-main-package-entry-point' instead

Warnings

breaking Removed 'ckeditor-imports' rule in v14.0.0 ↓

fix Use 'allow-imports-only-from-main-package-entry-point' rule instead

breaking Removed 'no-legacy-imports' rule in v14.0.0 ↓

fix Remove the rule from your config; it is no longer needed

deprecated The 'ckeditor5-rules/no-enum' rule is enabled by default in eslint-config-ckeditor5 since v15.0.0, disallowing enums unconditionally ↓

fix Use TypeScript union types instead of enums, or disable the rule if you must use enums

gotcha Requires Node.js >=24.11.0; older Node versions will cause runtime errors ↓

fix Upgrade Node.js to 24.11.0 or later

gotcha ESM-only package; cannot be used with CommonJS require or older ESLint (legacy .eslintrc) formats ↓

fix Use import syntax and ESLint flat config

breaking Enabled 'enforce-node-protocol' rule for all JS/TS files in v13.0.0 ↓

fix Ensure all 'node:' imports use the full URL (e.g., 'node:fs') or disable the rule

Install

npm install eslint-plugin-ckeditor5-rules

yarn add eslint-plugin-ckeditor5-rules

pnpm add eslint-plugin-ckeditor5-rules

Imports

default

wrong

const ckeditor5Rules = require('eslint-plugin-ckeditor5-rules')

correct

import ckeditor5Rules from 'eslint-plugin-ckeditor5-rules'

ESM-only package since v13; does not provide CommonJS export

plugins
wrong
```
plugins: ['ckeditor5-rules']
```
correct
```
plugins: { 'ckeditor5-rules': ckeditor5Rules }
```
ESLint flat config requires plugin object, not string array
rules
wrong
```
'no-relative-imports': 'error'
```
correct
```
'ckeditor5-rules/no-relative-imports': 'error'
```
Rule names must be prefixed with 'ckeditor5-rules/' in flat config

Quickstart

Minimal ESLint flat config using the plugin with two CKEditor 5 rules

import { defineConfig } from 'eslint/config';
import ckeditor5Rules from 'eslint-plugin-ckeditor5-rules';

export default defineConfig([
  {
    plugins: {
      'ckeditor5-rules': ckeditor5Rules
    },
    rules: {
      'ckeditor5-rules/no-relative-imports': 'error',
      'ckeditor5-rules/license-header': ['error', {
        headerLines: [
          '/**',
          ' * @license Copyright (c) 2003-2026, CKSource Holding sp. z o.o. All rights reserved.',
          ' * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license',
          ' */'
        ]
      }],
      'ckeditor5-rules/no-enum': 'error'
    }
  }
]);