Extensions

The extensions option enables specialized rule packs that are useful across many project types.

Install @santi020k/eslint-config-extensions alongside the lean basic package before enabling or auto-detecting entries on this page. The full package already includes it.

Extension	Enum	Use It When	Auto-Detected
RegExp	Extension.Regexp	The project wants stronger regular-expression linting.	No
Unicorn	Extension.Unicorn	The project wants modern JavaScript best-practice rules.	No
SonarJS	Extension.Sonarjs	The project wants maintainability-oriented rules.	No
Security	Extension.Security	The project wants additional security-oriented checks.	Yes
Perfectionist	Extension.Perfectionist	The project wants ordering and consistency rules.	No
BestPractices	Extension.BestPractices	The project wants light-weight quality rules with no extra dependencies.	No
Boundaries	Extension.Boundaries	The project wants dependency-free import boundary guardrails for package, generated-code, and test imports.	No
A11y	Extension.A11y	The project wants accessibility linting for JSX and Vue.	Yes
Biome	Extension.Biome	The project wants to enforce Biome formatting and rules.	No
Node	Extension.Node	The project is a Node.js codebase that wants eslint-plugin-n rules.	No
Compat	Extension.Compat	The project wants browser-compatibility checks against its browserslist.	No
DeMorgan	Extension.DeMorgan	The project wants negated logical expressions simplified automatically.	No
Depend	Extension.Depend	The project wants suggestions for lighter or native dependency alternatives.	No
Oxlint	Extension.Oxlint	The project runs Oxlint alongside ESLint and wants duplicate rules disabled.	No

Example

import { defineConfig, Extension } from '@santi020k/eslint-config-basic'

export default await defineConfig({
  extensions: [
    Extension.Unicorn, Extension.Security, Extension.Perfectionist, Extension.BestPractices, Extension.Boundaries
  ]
})

Details

BestPractices

The Extension.BestPractices pack adds four quality rules that don’t require any external plugin dependencies:

• no-console (warn) — catches leftover debug output
• no-alert (error) — disallows browser alert, confirm, and prompt
• complexity (warn, max 10) — flags overly complex functions
• max-depth (warn, max 4) — flags deeply nested blocks

Refactor a complexity finding when branches describe separable work, repeated decisions, or deeply nested control flow. A validator or release transaction that deliberately runs independent checks to return one complete report can merit a narrow source-level directive instead. Keep that directive on the smallest function and explain why preserving the complete transaction is more useful than splitting it.

To see the complexity ESLint counted for a file, run:

basic-eslint explain complexity --file src/validator.ts

The explanation includes each current complexity diagnostic and its source location. ESLint’s diagnostic reports the calculated complexity and configured maximum.

Boundaries

The Extension.Boundaries pack adds dependency-free import guardrails:

• import/no-relative-packages (warn) — catches relative imports across package boundaries.
• import/no-self-import (error) — prevents a module from importing itself.
• no-restricted-imports (error) — blocks production imports from generated-code and test-only paths.

Node

The Extension.Node pack applies eslint-plugin-n recommended rules. Module-resolution rules (n/no-missing-import, n/no-missing-require) are disabled for TypeScript files because the compiler already validates imports.

Oxlint

The Extension.Oxlint pack disables ESLint rules already covered by Oxlint so both linters can run side by side without duplicate reports — the same hybrid-linting model as the Biome extension.

Example usage:

import { defineConfig, Extension } from '@santi020k/eslint-config-basic'

export default await defineConfig({
  extensions: [
    // other extensions...
    Extension.Oxlint
  ]
})

By adding this extension, ESLint will no longer report errors for rules that Oxlint can check. You are expected to run oxlint manually (e.g., in your CI pipeline or package.json lint scripts) alongside eslint to catch those issues much faster.

Notes

• The Security extension is enabled by default through detection.
• These extensions can be layered with frameworks, formats, and tooling without changing the core composition model.
• Like Prettier and Biome, the Oxlint extension is applied after other extensions so its rule disables win.

Repository Examples

• Extension Playgrounds: packages/playground/extensions
• Extensions Package Source: packages/extensions