guide

A usage guide for es-toolkit, a JavaScript and TypeScript utility library.

In plain words
What is it for?
Use it to check how es-toolkit is installed, find the correct package version and exports, and choose commands for npm, Yarn, pnpm, or Bun projects.
Why use it?
It helps avoid incorrect installation commands or import paths when package versions and project runtimes differ.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/toss/es-toolkit/guide
Any agent
npx skills add toss/es-toolkit --skill guide
Clone the repo
git clone --depth 1 https://github.com/toss/es-toolkit

Made for: Claude Code, Codex.

Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 905 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00048 $0.00905
Opus 5 $0.00024 $0.00452
Sonnet 5 $0.00010 $0.00181
Haiku 4.5 $0.00005 $0.00090

Measured 2d ago against content hash b177221cff54, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

guide scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

es-toolkit-plugin/skills/guide/SKILL.md · 77 lines

How it starts

The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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:

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.

Read the full file on GitHub · 77 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 77 lines · 48 tokens per session scan A b177221cff54

Subscribe to this mod's changes

guide is a skill published in the GitHub repository toss/es-toolkit (11,316 stars, last pushed 2d ago), licensed MIT. It adds 48 tokens to every session and 905 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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