antfu

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name: antfu description: Anthony Fu's opinionated tooling and conventions for JavaScript/TypeScript projects. Use when setting up new projects, configuring ESLint/Prettier alternatives, monorepos, library publishing, or when the user mentions Anthony Fu's preferences. metadata: author: Anthony Fu version: "2026.09.30"

Reference template: antfu/starter-ts. When scaffolding a new TypeScript project, mirror its package.json scripts, eslint.config.js, knip.json, tsdown.config.ts and workflows rather than inventing a new layout.

Coding Practices

Code Organization

• Single responsibility: Each source file should have a clear, focused scope/purpose
• Split large files: Break files when they become large or handle too many concerns
• Type separation: Always separate types and interfaces into types.ts or types/*.ts
• Constants extraction: Move constants to a dedicated constants.ts file

Runtime Environment

• Prefer isomorphic code: Write runtime-agnostic code that works in Node, browser, and workers whenever possible
• Clear runtime indicators: When code is environment-specific, add a comment at the top of the file:

// @env node
// @env browser

TypeScript

• Explicit return types: Declare return types explicitly when possible
• Avoid complex inline types: Extract complex types into dedicated type or interface declarations

Explicitness

Favor explicit, traceable code over implicit "magic". A reader (human or agent) should be able to follow where every name comes from without running tooling.

• Explicit imports: Prefer explicit import statements. Avoid auto-imports — when a framework provides them (e.g. Nuxt/Nitro), turn them off for new projects (see app-development).
• No path aliases by default: Use relative imports (./foo, ../bar). Only use path aliases (@/, ~/, #imports, etc.) when they are already configured in the project; don't introduce new ones for greenfield code.

Comments

• Avoid unnecessary comments: Code should be self-explanatory
• Explain "why" not "how": Comments should describe the reasoning or intent, not what the code does

Testing (Vitest)

• Test files: foo.ts → foo.test.ts (same directory)
• Use describe/it API (not test)
• Use toMatchSnapshot for complex outputs
• Use toMatchFileSnapshot with explicit path for language-specific snapshots

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Tooling Choices

@antfu/ni Commands

Command	Description
ni	Install dependencies
ni <pkg> / ni -D <pkg>	Add dependency / dev dependency
nr <script>	Run script
nu	Upgrade dependencies
nun <pkg>	Uninstall dependency
nci	Clean install (pnpm i --frozen-lockfile)
nlx <pkg>	Execute package (npx)

Checking npm Package Versions

Use fast-npm-meta to look up the latest version of a package — it queries a small metadata endpoint instead of downloading the full registry payload (which can be megabytes per package).

nlx fast-npm-meta version vite              # 7.3.1
nlx fast-npm-meta version "nuxt@^3.5"       # 3.5.22 — range-aware
nlx fast-npm-meta version vite nuxt vue     # multiple at once
nlx fast-npm-meta version vite --json       # JSON for scripting
nlx fast-npm-meta full vite                 # full version list + dist-tags

Prefer this over npm view <pkg> version when you only need the latest version, and over reading package.json from the registry directly.

TypeScript Config

{
  "compilerOptions": {
    "target": "ESNext",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true
  }
}

ESLint Setup

// eslint.config.js
import antfu from '@antfu/eslint-config'

export default antfu({
  type: 'lib', // or 'app' (default)
  pnpm: true, // enforce pnpm catalogs in package.json
  antislop: true, // flag redundant/duplicated AI-style code, ban explicit `any`
})

Always enable antislop: true. It requires eslint-plugin-slop and eslint-plugin-sonarjs as dev dependencies.

For detailed configuration options: antfu-eslint-config

Knip

Use Knip to catch unused files, exports and dependencies — the linter only sees one file at a time.

// knip.json
{
  "$schema": "https://unpkg.com/knip@6/schema.json",
  "project": ["src/**/*.ts"],
  "ignoreDependencies": []
}

Fix what Knip reports by deleting; only add to ignoreDependencies for tools invoked outside package.json scripts (e.g. taze).

Scripts and the ci Gate

Every project exposes a ci script that runs all checks in one command:

{
  "scripts": {
    "build": "tsdown",
    "lint": "eslint --cache",
    "typecheck": "tsc",
    "knip": "knip",
    "test": "pnpm run build && vitest",
    "ci": "pnpm run lint && pnpm run typecheck && pnpm run knip && pnpm run test --run"
  }
}

Before every commit, run nr lint --fix to format, then nr ci and make sure it passes. Do not commit with a failing ci; fix the root cause instead of silencing rules or adding ignores.

Git Hooks

simple-git-hooks + nano-staged. The pre-commit hook runs the full ci gate; prepare also installs agent skills via skills-npm:

{
  "scripts": {
    "prepare": "git config core.hooksPath .githooks && simple-git-hooks && skills-npm"
  },
  "simple-git-hooks": {
    "pre-commit": "pnpm i --frozen-lockfile --ignore-scripts --offline && pnpm run ci && pnpx nano-staged"
  },
  "nano-staged": {
    "*": "eslint --fix --no-warn-ignored"
  }
}

Add .githooks to .gitignore and simple-git-hooks: true under allowBuilds in pnpm-workspace.yaml.

skills-npm

skills-npm symlinks agent skills shipped inside installed npm packages (and fetches those declared in a skills field) into the agent's skills directory on every install. Install as a dev dependency and wire it into prepare as above; add skills/npm-* to .gitignore. Commit the generated skills-npm-lock.json.

Publishing

Prefer npm Trusted Publishing (OIDC) over NPM_TOKEN secrets: releases run on CI from a v* tag via release.yml with id-token: write, and nr release (bumpp) only bumps, tags and pushes. Details: setting-up.

pnpm Catalogs

Use named catalogs in pnpm-workspace.yaml for version management:

Catalog	Purpose
prod	Production dependencies
inlined	Bundler-inlined dependencies
dev	Dev tools (linter, bundler, testing)
frontend	Frontend libraries

Avoid the default catalog. Catalog names can be adjusted per project needs.

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References

Topic	Description	Reference
ESLint Config	Framework support, antislop, formatters, rule overrides, VS Code settings	antfu-eslint-config
Project Setup	.gitignore, GitHub Actions, OIDC trusted publishing, VS Code extensions	setting-up
App Development	Vue/Nuxt/UnoCSS conventions, auto-import control, Storybook component testing	app-development
Library Development	tsdown bundling, pure ESM publishing, publint, API snapshots	library-development
Monorepo	pnpm workspaces, centralized alias, Turborepo	monorepo