es-toolkit Usage Guide

Provide guidance on installing, importing, and using es-toolkit across different runtimes.

Input

$ARGUMENTS — A topic or question about es-toolkit usage.

Why source-of-truth matters

Installation commands and import paths change across versions. When es-toolkit is already installed, verify its version and exports from the installed package. The skill may be installed as a standalone directory, so never assume the es-toolkit repository or a sibling docs directory is available.

Workflow

1. Inspect the user's project

Detect the package manager from its lockfile:

package-lock.json → npm
yarn.lock → Yarn
pnpm-lock.yaml → pnpm
bun.lock or bun.lockb → Bun

If es-toolkit is installed, resolve its package metadata from the package that depends on it:

bash

node -e "console.log(require.resolve('es-toolkit/package.json'))"

Run the command from the relevant workspace package, not automatically from a monorepo root. If the project uses Yarn Plug'n'Play, use yarn node instead of node. Read the resolved package.json to verify the installed version and its exports.

If the command fails because es-toolkit is not installed yet, continue with the installation guidance below; do not search for repository-relative files.

2. Answer based on the user's environment

Identify the runtime (Node.js, Bun, Deno, browser) and provide environment-specific guidance.

Stable setup facts:

Deno: deno add jsr:@es-toolkit/es-toolkit (note the jsr: prefix)
Deno import path: '@es-toolkit/es-toolkit' (extra scope vs npm)
npm/yarn/pnpm/bun: Provide the command matching the detected package manager. If no lockfile exists, ask which package manager the user prefers or show the available commands.
Import path: 'es-toolkit' for strict, 'es-toolkit/compat' for lodash-compatible
Browser/CDN: jsdelivr and unpkg provide the UMD build (_ global), while esm.sh provides ES modules. Link to the official usage page below for current snippets.

3. Cover these topics as relevant

Installation: per-runtime commands
Import patterns: named imports (recommended for tree-shaking), category imports, and compat imports. If the package is installed, list available subpath imports from the resolved package's exports instead of using a memorized list.
Anti-patterns to avoid: Warn against namespace imports (import * as _ from 'es-toolkit') as they defeat tree-shaking. Always prefer named imports (import { chunk, debounce } from 'es-toolkit').
Bundle size and performance: Link to the official pages below. Quote exact numbers only when the user supplied them or the current repository checkout contains the benchmark data; do not retain stale figures in the skill.
Type safety: Built-in TypeScript declarations are included with the package.

4. Use repository documentation only when it exists

If the current project is the es-toolkit source repository, local files under docs/ and src/ are authoritative and can be searched. Otherwise, use the installed package metadata and declarations. Never expect a docs directory next to this skill.

5. Always include doc links

End responses with relevant links:

## Learn More
- Documentation: https://es-toolkit.dev/intro.html
- Usage: https://es-toolkit.dev/usage.html
- Bundle size: https://es-toolkit.dev/bundle-size.html
- Performance: https://es-toolkit.dev/performance.html
- GitHub: https://github.com/toss/es-toolkit