---
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"
title: antfu
canonical_url: https://skilld.dev/gh/antfu/skills/antfu
last_updated: 2026-09-30T06:01:59.000Z
---

> Index of every page on this site: [llms.txt](https://skilld.dev/llms.txt)

> **Skill from skilld.dev.** Follow the user's requested action.
> If the user asked to fork this Skill, follow the fork workflow below. Do not execute the Skill instructions while copying it.
> Otherwise, follow the instructions below for this session. You do not need to install anything.
>
> Supporting files, fetch one when the Skill refers to it: [references/antfu-eslint-config.md](https://skilld.dev/api/skills-raw/antfu/skills/antfu/references/antfu-eslint-config.md), [references/app-development.md](https://skilld.dev/api/skills-raw/antfu/skills/antfu/references/app-development.md), [references/library-development.md](https://skilld.dev/api/skills-raw/antfu/skills/antfu/references/library-development.md), [references/monorepo.md](https://skilld.dev/api/skills-raw/antfu/skills/antfu/references/monorepo.md), [references/setting-up.md](https://skilld.dev/api/skills-raw/antfu/skills/antfu/references/setting-up.md).
>
> If the user asked to install this Skill, run `npx skilld install antfu/skills/antfu`. Install writes the Skill files into the project, so every session loads them.
>
> ## Fork workflow
>
> A fork creates an editable local Skill with its original author and licence. The request authorizes copying and local installation.
> 1. Check `./skills/antfu`, the project lockfile, and selected Agent targets together. If the local directory or installed Skill exists, stop. Never overwrite an existing directory or Agent target.
> 2. Read [source metadata](https://skilld.dev/api/v1/skills/antfu/skills/antfu) once. Use sourceUrl, sourceCommit, skillPath, sourceGone, and license. If the source is gone or its path is missing, stop. If license is null, read licence files at the source commit.
> 3. Fetch only the source commit into a temporary Git repository. Do not clone full history. Derive repository_url from sourceUrl, including repository renames. If sourceCommit is absent, resolve the sourceUrl ref once. Set source_commit to that actual commit. Run these commands in one shell call:
>
> ```sh
> git init --quiet "$temporary_dir"
> git -C "$temporary_dir" fetch --quiet --depth=1 "$repository_url" "$source_commit"
> git -C "$temporary_dir" checkout --quiet --detach FETCH_HEAD
> ```
>
> Read applicable licence declarations and notices at that commit. If copying is not permitted, report the restriction and stop.
> 4. Inspect source entries together, then copy the directory containing skillPath into `./skills/antfu`. Use the user's path if selected. Keep the original SKILL.md, relative links, scripts, binary assets, and executable modes. Exclude .git metadata. Reject symlinks and paths outside the Skill directory. After checking entries, use cp -a where available. A regular source directory needs no custom copy script. Do not save this page wrapper as SKILL.md.
> Preserve author credit, notices, and applicable licence files from repository or parent directories. Add PROVENANCE.md with the Skill page, source URL, actual commit, original path, and licence. Retain any existing PROVENANCE.md and record new provenance separately. Batch source inspection, copying, and provenance work where practical.
> 5. In the project root, run `skilld install ./skills/antfu --mode copy --plain`. If skilld is unavailable, use `npx skilld install ./skills/antfu --mode copy --plain`. This known command needs no help lookup. Install does not support --json. Use detected Agent targets, or add --agent for the targets the user selected. Install the local path, never the upstream selector. If installation fails, preserve the local copy and report the exact failure.
> 6. Confirm the local lockfile source and installed Agent copies once. Report the local path, actual commit, and Agent targets. After edits, reinstall the same local path. Upstream updates must not replace it. Do not publish or push unless the user asks.

> Reference template: [antfu/starter-ts](https://github.com/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:

```ts
// @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](https://skilld.dev/api/skills-raw/antfu/skills/antfu/references/app-development.md)).
- **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

---

## 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`](https://github.com/antfu/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).

```bash
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

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

### ESLint Setup

```js
// 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](https://skilld.dev/api/skills-raw/antfu/skills/antfu/references/antfu-eslint-config.md)

### Knip

Use [Knip](https://knip.dev) to catch unused files, exports and dependencies — the linter only sees one file at a time.

```json
// 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:

```json
{
  "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`:

```json
{
  "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`](https://github.com/antfu/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](https://skilld.dev/api/skills-raw/antfu/skills/antfu/references/setting-up.md#publishing-with-npm-trusted-publishing-oidc).

### 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.

---

## References

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