Legacy Config

The Legacy Config is designed for teams who want a One-To-One/Drop-In Replacement for the original Airbnb ESLint configs, but with support for Flat Config (ESLint 9+).

Instead of rewriting rules, this mode focuses on parity and smooth migration. If your team already uses:

• eslint-config-airbnb
• eslint-config-airbnb-base
• eslint-config-airbnb-typescript

You can switch to eslint-config-airbnb-extended/legacy with minimal diffs while being future-ready.

Overview

The legacy entrypoint provides:

• Configs → Predefined sets of rules that map directly to the Airbnb family.
• Rules → Core rule groups that enforce good coding practices and are used in configs.

This ensures your project setup is familiar, stable, and ESLint 9-ready.

Configs

The configs mirror the original Airbnb packages, making migration straightforward.

1. For eslint-config-airbnb-base

Use this if you want only JavaScript base rules without React or TypeScript.

eslint.config.mjs

import { configs } from 'eslint-config-airbnb-extended/legacy';

// Equivalent to airbnb-base/legacy
export default [...configs.base.legacy];

// Equivalent to airbnb-base
export default [...configs.base.recommended];

2. For eslint-config-airbnb

Use this when working with React. It provides a one-to-one mapping with all the standard Airbnb React presets, including hooks.

eslint.config.mjs

import { configs } from 'eslint-config-airbnb-extended/legacy';

// Equivalent to airbnb/legacy
export default [...configs.react.legacy];

// Equivalent to airbnb/base
export default [...configs.react.base];

// Equivalent to airbnb
export default [...configs.react.recommended];

// Equivalent to airbnb/hooks
export default [...configs.react.hooks];

3. For eslint-config-airbnb-typescript

Use this if you’re on TypeScript and want the Airbnb TypeScript rules, but in Flat Config format without breaking compatibility.

eslint.config.mjs

import { configs } from 'eslint-config-airbnb-extended/legacy';

// Equivalent to airbnb-typescript/base
export default [...configs.base.typescript];

// Equivalent to airbnb-typescript
export default [...configs.react.typescript];

Rules

The rules are the building blocks of configs. Each config combines these rule groups.

Base Rules

Rule Group	Description
Best Practices	Enforces common best practices to improve code quality and maintainability.
Errors	Helps catch runtime errors and unsafe patterns early.
ES6	Provides rules specific to ES6+ syntax and features.
Imports	Ensures proper import/export usage with eslint-plugin-import.
Node	Includes Node.js-specific rules for server-side development.
Strict	Enables strict mode rules.
Style	Covers general code style rules such as spacing, quotes, and semicolons.
Variables	Validates variable declarations, usage, and scoping rules.

React Rules

Rule Group	Description
Base	Core React rules for JSX and component structure.
JSX Accessibility	Accessibility rules via eslint-plugin-jsx-a11y for inclusive UIs.
Hooks	Rules from eslint-plugin-react-hooks ensuring proper hook usage.

TypeScript Rules

Rule Group	Description
Base	Core TypeScript linting rules for types, syntax, and consistency.
Overrides	Adjusts ESLint by disabling rules covered by TypeScript and enabling ones that benefit from type-checking.
Settings	Additional config values for TypeScript resolver and parser options.

Why Legacy Config Exists

• ✅ 1:1 replacements → drop-in equivalents of Airbnb configs.
• ✅ Flat Config ready → works with ESLint 9 and beyond.
• ✅ Migration path → lets you start simple, then move to extended or strict configs later.
• ✅ Less churn → developers see fewer rule changes when upgrading.

If you’re upgrading a project that already relies on Airbnb configs, start with Legacy Config to make the transition safe and low-friction. Once you’re stable, you can move on to Extended (modernized rules) or even Strict Mode for maximum consistency.