eslint-plugin-fsecond

1.5.0 verified Sat Apr 25 auth: no javascript

ESLint plugin providing opinionated rules for JavaScript, TypeScript, and React projects. Current stable version is 1.5.0 (February 2026). Requires Node.js >=22 and ESLint >=9.0.0. Supports TypeScript via peer dependency typescript >=5.0.0. Key differentiators: includes rules like no-inline-interfaces (auto-fixable), prefer-destructured-optionals, valid-event-listener, and no-redundant-jsx-prop-usage (requires type information). Offers recommended and recommendedTypeChecked configs. Actively maintained with regular releases.

Common errors

error Error [ERR_REQUIRE_ESM]: require() of ES Module ... ↓

cause Package is ESM-only; using require() in a CommonJS file.

fix

Switch to import syntax or use dynamic import: const fsecond = await import('eslint-plugin-fsecond');

error ESLint couldn't find the plugin "eslint-plugin-fsecond". Are you sure it's installed? ↓

cause ESLint plugin not installed or not in node_modules.

fix

Run: pnpm add -D eslint-plugin-fsecond

Warnings

breaking Node.js >=22 required; older Node versions are not supported. ↓

fix Upgrade Node.js to version 22 or higher.

breaking ESLint >=9.0.0 required; flat config only (no .eslintrc). ↓

fix Migrate to ESLint flat config (eslint.config.js/ts) and upgrade ESLint to 9+.

deprecated The rule 'valid-event-listener' has an option 'checkWindowListener' that was deprecated in v1.1.0; use 'checkGlobalListeners' instead. ↓

fix Replace 'checkWindowListener' with 'checkGlobalListeners' in rule options.

gotcha Default import is ESM-only; require() will throw an error. ↓

fix Use import statements or dynamic import().

Install

npm install eslint-plugin-fsecond

yarn add eslint-plugin-fsecond

pnpm add eslint-plugin-fsecond

Imports

fsecond
wrong
```
const fsecond = require('eslint-plugin-fsecond')
```
correct
```
import fsecond from 'eslint-plugin-fsecond'
```
Default import of the plugin object. ESM-only as the package does not export a CommonJS entry point.
fsecond.configs.recommended
wrong
```
import { configs } from 'eslint-plugin-fsecond'
```
correct
```
import fsecond from 'eslint-plugin-fsecond'; export default [...fsecond.configs.recommended]
```
Accessing configs via named import may fail because the default export is the plugin object with a configs property.

no-inline-interfaces

wrong

import { rules } from 'eslint-plugin-fsecond'

correct

import fsecond from 'eslint-plugin-fsecond'; ... rules: { 'fsecond/no-inline-interfaces': 'error' }

Rules are accessed via the plugin prefix in ESLint configs, not by importing individual rule objects.

Quickstart

Shows how to use the recommended config and override a rule with options.

// eslint.config.ts
import fsecond from 'eslint-plugin-fsecond';

export default [
  ...fsecond.configs.recommended,
  {
    rules: {
      'fsecond/no-inline-interfaces': ['error', { allowObjectTypes: false }],
    },
  },
];