eslint-config-biome

2.1.3 verified Sat Apr 25 auth: no javascript

An ESLint shareable config that disables ESLint rules which have an equivalent and recommended rule in Biome, enabling simultaneous use of Biome and ESLint without conflicts. Current stable version: 2.1.3. Released on Biome version bumps; includes eslint-config-prettier to also disable formatting rules. Key differentiator: automates disabling overlapping rules, works with both flat config (ESLint v9+) and .eslintrc (v8).

Common errors

error Error [ERR_REQUIRE_ESM]: require() of ES Module /path/to/node_modules/eslint-config-biome/index.js not supported. ↓

cause Using CommonJS require() on an ESM-only package (v1.8.3+).

fix

Switch to import syntax (ESM) or use dynamic import() if using CommonJS.

error Failed to load config "biome" to extend from. ↓

cause Using flat config but incorrectly providing a string in extends or an object without the default import.

fix

Use import biome from 'eslint-config-biome' and add the biome object directly to the array.

error ESLint configuration error: The "extends" property is not supported in flat config. ↓

cause Trying to use extends in flat config (ESLint v9).

fix

Use the array-based flat config: export default [ /* other configs */, biome ];

error Parsing error: The keyword 'import' is reserved ↓

cause Using import in a CommonJS file without ESM configured.

fix

Add "type": "module" in package.json or use .mjs extension for the config file.

Warnings

breaking Version 1.8.3+ requires ESLint v8.40+ for Flat Config support; older ESLint versions must use .eslintrc with overrides. ↓

fix Upgrade ESLint to v8.40+ or use .eslintrc with overrides (not extends).

gotcha This config must be the last item in the flat config array or the last override in .eslintrc to effectively disable conflicting rules. ↓

fix Ensure biome config is placed after all other configs (last in array or overrides list).

gotcha The package automatically includes eslint-config-prettier, so do not add it separately to avoid duplicates. ↓

fix Remove eslint-config-prettier from your dependencies and ESLint config.

deprecated Using top-level extends with 'biome' in .eslintrc is deprecated; use overrides instead. ↓

fix Move the biome config into the overrides array as shown in the quickstart.

gotcha ESLint v9 flat config expects a default import; require() will throw an error. ↓

fix Use import biome from 'eslint-config-biome' instead of require.

Install

npm install eslint-config-biome

yarn add eslint-config-biome

pnpm add eslint-config-biome

Imports

default export (biome)

wrong

const biome = require('eslint-config-biome');

correct

import biome from 'eslint-config-biome';

Package is ESM-only; CommonJS require() will fail.

Flat config usage

wrong

module.exports = { extends: ['biome'] };

correct

import biome from 'eslint-config-biome';
export default [ /* other configs */, biome ];

Flat config (ESLint v9+) expects an array; the old extends pattern is not supported.

Legacy .eslintrc usage

wrong

// extends at top level
extends: ['biome']

correct

// overrides section
overrides: [{ files: ['*.ts', '*.js', '*.tsx', '*.jsx'], extends: ['biome'] }]

Using extends at top level may cause ordering issues; overrides ensures last evaluation.

Quickstart

Demonstrates installation and configuration for both flat config and legacy .eslintrc, ensuring Biome and ESLint work together without conflicts.

// 1. Install
npm install -D eslint-config-biome

// 2. ESLint flat config (eslint.config.js)
import biome from 'eslint-config-biome';

export default [
  // other configs...
  biome, // must be last to override others
];

// 3. Alternatively, .eslintrc.json (ESLint v8 or flat config emulation)
{
  "overrides": [
    {
      "files": ["*.ts", "*.js", "*.tsx", "*.jsx"],
      "extends": ["biome"]
    }
  ]
}