tooling/eslint-flat-config

Why

ESLint 10 reads only eslint.config.js (or .mjs, .cjs, .ts); an .eslintrc* file or an eslintConfig key in package.json is no longer used, and .eslintignore is not read. A project that upgraded without migrating lints with a config nobody wrote, or not at all, while the old file suggests otherwise. Next.js 16 also removed next lint.

Fix

Migrate with npx @eslint/migrate-config .eslintrc.json, move ignore patterns into an ignores entry (or globalIgnores()), delete the old files, and run eslint . from a package script. A TypeScript config file (eslint.config.ts) needs jiti as a dev dependency on Node.

Examples

// eslint.config.js
import js from '@eslint/js'
import { defineConfig, globalIgnores } from 'eslint/config'
export default defineConfig([globalIgnores(['dist/']), js.configs.recommended])

Sources

• ESLint, Configuration files
• ESLint, Configuration migration guide

Read it in the terminal

npx github:dawidolko/frontend-skills explain tooling/eslint-flat-config