eslint-plugin-complexity

1.0.2 verified Sat Apr 25 auth: no javascript

ESLint plugin providing additional complexity-related rules beyond ESLint's built-in complexity rule. Version 1.0.2 is the latest stable release, published on npm. It adds a custom rule 'complexity/comment' to warn when a function's cyclomatic complexity exceeds a configurable maximum. Differentiator: focused solely on complexity with a comment-based rule, not a general-purpose plugin.

Common errors

error Configuration for rule "complexity/comment" is invalid: Value "{max:10}" should be object. ↓

cause Configuration of rule 'complexity/comment' is not an object with max property.

fix

Use { max: 10 } with quotes: 'complexity/comment': ['warn', { max: 10 }]

error ESLint couldn't find the plugin "eslint-plugin-complexity". ↓

cause Plugin not installed or not listed in plugins array correctly.

fix

Run npm i eslint-plugin-complexity -D and add 'complexity' to plugins array in config.

Warnings

gotcha Rule 'complexity/comment' only checks functions with a leading comment (e.g., /* complexity: 5 */). Without a comment, no warning is emitted. ↓

fix Ensure a comment like '/* complexity: N */' is present before the function to be checked.

Install

npm install eslint-plugin-complexity

yarn add eslint-plugin-complexity

pnpm add eslint-plugin-complexity

Imports

default export (plugin object)
wrong
```
const complexity = require('eslint-plugin-complexity')
```
correct
```
import complexity from 'eslint-plugin-complexity'
```
ESLint plugins are typically used via plugins array in config, not direct import in code.

Flat config (ESLint 9+)

wrong

module.exports = { plugins: ['complexity'], rules: { 'complexity/comment': 'warn' } }

correct

import complexity from 'eslint-plugin-complexity';
export default [ { plugins: { complexity }, rules: { 'complexity/comment': 'warn' } } ]

With flat config, import the plugin object and assign to plugins property.

Legacy .eslintrc config

wrong

import complexity from 'eslint-plugin-complexity';
export default { plugins: { complexity }, rules: { 'complexity/comment': 'warn' } }

correct

module.exports = { plugins: ['complexity'], rules: { 'complexity/comment': 'warn' } }

Legacy config uses string in plugins array; flat config uses object.

Quickstart

Configures ESLint to warn when function cyclomatic complexity exceeds 10 using the comment rule.

module.exports = {
  plugins: ['complexity'],
  rules: {
    'complexity/comment': ['warn', { max: 10 }]
  }
};