skill CX Codex

javascript-mastery — Claude Code skill: what it does, install

Q: How do I install javascript-mastery in Claude Code?

Run `npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a claude-code`, then run `npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a claude-code` again. The skill file is at `~/.claude/skills/javascript-mastery/SKILL.md`.

Q: What should I read before running javascript-mastery?

Read `references/detailed-guide.md` first. It contains the procedure, reference material, safety requirements, and validation checks.

A skill for 33+ JavaScript concepts, tricky behavior, fundamentals, and code reviews. Use it when you need a focused explanation or debugging help.

Install into Claude Code · Skills CLI (Vercel) All methods and platforms ↓

npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a claude-code

Open on GitHub

What javascript-mastery does

javascript-mastery covers 33+ JavaScript concepts and is aimed at explaining the language, debugging tricky JS behavior, teaching fundamentals, reviewing code practices, and examining language quirks. It gives an agent a defined scope for JavaScript-focused questions.

Read references/detailed-guide.md before running the skill. The guide contains the full procedure, reference material, safety requirements, and validation checks; focused tasks can load relevant sections, while end-to-end work uses the complete guide. The skill does not replace environment-specific validation, testing, or expert review, so its output still needs to be checked against the project.

What it helps with

explain a JavaScript concept
debug tricky JS behavior
teach JavaScript fundamentals
review code for JS best practices
investigate a language quirk

Example prompts for the agent

Use the javascript-mastery skill to explain closures in this JavaScript code.
Apply javascript-mastery and find why this JS code behaves unexpectedly.
Review this file for JavaScript best practices with the javascript-mastery skill.

How to install javascript-mastery

1Skills CLI (Vercel)

npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a claude-code

2Manually: put the files in place

~/.claude/skills/javascript-mastery/SKILL.md

Copy the whole skill folder; for one project use .claude/skills/javascript-mastery/

1Skills CLI (Vercel)

npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a codex

2Manually: put the files in place

.agents/skills/javascript-mastery/SKILL.md

For all projects use ~/.agents/skills/

1Skills CLI (Vercel)

npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a cursor

2Manually: put the files in place

.cursor/skills/javascript-mastery/SKILL.md

Cursor also reads .agents/skills/ and .claude/skills/

1GitHub CLI

gh skill install sickn33/agentic-awesome-skills javascript-mastery

2Manually: put the files in place

.github/skills/javascript-mastery/SKILL.md

1Skills CLI (Vercel)

npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a gemini-cli

2Platform CLI

gemini skills install https://github.com/sickn33/agentic-awesome-skills --path skills/javascript-mastery

Manually: put the files in place

.devin/skills/javascript-mastery/SKILL.md

The legacy .windsurf/skills/ path still works

Skills CLI (Vercel)

npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a opencode

Step by step, with commands for each platform: How to install skills in Claude Code: five ways

Questions about javascript-mastery

How do I install javascript-mastery in Claude Code?

Run npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a claude-code, then run npx skills add sickn33/agentic-awesome-skills --skill javascript-mastery -a claude-code again. The skill file is at ~/.claude/skills/javascript-mastery/SKILL.md.

What does javascript-mastery do?

It helps explain 33+ JavaScript concepts, teach fundamentals, debug difficult JS behavior, review language practices, and examine JavaScript quirks.

What should I read before running javascript-mastery?

Read references/detailed-guide.md first. It contains the procedure, reference material, safety requirements, and validation checks.

Source text

SKILL.md · MIT

---
name: javascript-mastery
description: "33+ essential JavaScript concepts every developer should know, inspired by [33-js-concepts](https://github.com/leonardomso/33-js-concepts)."
risk: critical
source: community
date_added: "2026-02-27"
---

# 🧠 JavaScript Mastery

> 33+ essential JavaScript concepts every developer should know, inspired by [33-js-concepts](https://github.com/leonardomso/33-js-concepts).

## Detailed Guide

Read [the detailed guide](references/detailed-guide.md) before executing this skill. It retains the complete procedure and reference material. Treat its safety, prerequisites, and validation requirements as mandatory. For focused work, load the relevant sections; for end-to-end work, read the guide completely.

## When to Use This Skill

Use this skill when:

- Explaining JavaScript concepts
- Debugging tricky JS behavior
- Teaching JavaScript fundamentals
- Reviewing code for JS best practices
- Understanding language quirks

---

## Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

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