linting-neostandard-eslint9

name	linting-neostandard-eslint9
description	Configures ESLint v9 flat config and neostandard for JavaScript and TypeScript projects, including migrating from legacy `.eslintrc*` files or the `standard` package. Use when you need to set up or fix linting with `eslint.config.js` or `eslint.config.mjs`, troubleshoot lint errors, configure neostandard rules, migrate from `.eslintrc` to flat config, or integrate linting into CI pipelines and pre-commit hooks.
metadata	{"tags":"linting, neostandard, eslint, eslint9, flat-config, javascript, typescript"}

When to use

Use this skill when you need to:

• Set up linting in a JavaScript or TypeScript project
• Use neostandard as a Standard-like ESLint v9 flat-config baseline
• Configure eslint@9 with the flat config system (eslint.config.js/eslint.config.mjs)
• Migrate from standard to neostandard or ESLint v9
• Migrate from legacy .eslintrc* configuration to ESLint v9
• Run linting consistently in CI and local development

Quick start: basic neostandard setup

Install dependencies and create a minimal eslint.config.js:

npm install --save-dev eslint@9 neostandard

// eslint.config.js
import neostandard from 'neostandard'

export default neostandard()

Verify the config works:

npx eslint .

Common setup workflow (new project)

1. Install eslint@9 and neostandard (see Quick start above)
2. Create eslint.config.js with neostandard() as the base
3. Add any project-specific rule overrides on top
4. Run npx eslint . to confirm no config errors
5. Add a lint script to package.json: "lint": "eslint ."
6. Integrate into CI with a non-fix run; use --fix only in local workflows

How to use

Read individual rule files for implementation details and examples:

• rules/neostandard.md - Install, configure, and extend neostandard with ESLint
• rules/eslint-v9-flat-config.md - Build ESLint v9 flat config for JS/TS projects
• rules/migration-from-standard.md - Migrate from standard to neostandard or ESLint v9
• rules/migration-from-legacy-eslint.md - Migrate from .eslintrc* to flat config safely
• rules/ci-and-editor-integration.md - CI scripts, pre-commit, and editor setup

Core principles

• Prefer reproducible linting with pinned major versions
• Keep config minimal and explicit
• Use flat config for ESLint v9 projects
• Treat lint failures as quality gates in CI
• Enable auto-fix for local workflows, but validate with non-fix CI runs