javascript-pro
Writes, debugs, and refactors JavaScript code using modern ES2023+ features, async/await patterns, ESM module systems, and Node.js APIs. Use when building vanilla JavaScript applications, implementing Promise-based async flows, optimising browser or Node.js performance, working with Web Workers or Fetch API, or reviewing .js/.mjs/.cjs files for correctness and best practices.
npx skills add Jeffallan/claude-skills --skill javascript-pro --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# JavaScript Pro ## When to Use This Skill - Building vanilla JavaScript applications - Implementing async/await patterns and Promise handling - Working with modern module systems (ESM/CJS) - Optimizing browser performance and memory usage - Developing Node.js backend services - Implementing Web Workers, Service Workers, or browser APIs ## Core Workflow 1. **Analyze requirements** — Review `package.json`, module system, Node version, browser targets; confirm `.js`/`.mjs`/`.cjs` conventions 2. **Design architecture** — Plan modules, async flows, and error handling strategies 3. **Implement** — Write ES2023+ code with proper patterns and optimisations 4. **Validate** — Run linter (`eslint --fix`); if linter fails, fix all reported issues and re-run before proceeding. Check for memory leaks with DevTools or `--inspect`, verify bundle size; if leaks are found, resolve them before continuing 5. **Test** — Write comprehensive tests with Jest achieving 85%+ coverage; if coverage falls short, add missing cases and re-run. Confirm no unhandled Promise rejections ## Reference Guide Load detailed guidance based on context: | Topic | Reference | Load When | |-------|-----------|-----------| |
- When to Use This Skill
- Core Workflow
- Reference Guide
- Constraints
- MUST DO
- MUST NOT DO
- Key Patterns with Examples
- Async/Await Error Handling
- Optional Chaining & Nullish Coalescing
- ESM Module Structure
- Avoid var / Prefer const
- Output Templates
What does the javascript-pro skill do?
Writes, debugs, and refactors JavaScript code using modern ES2023+ features, async/await patterns, ESM module systems, and Node.js APIs. Use when building vanilla JavaScript applications, implementing Promise-based async flows, optimising browser or Node.js performance, working with Web Workers or Fetch API, or reviewing .js/.mjs/.cjs files for correctness and best practices.
How do I install it?
Run `npx skills add Jeffallan/claude-skills --skill javascript-pro --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From Jeffallan/claude-skills, a repository with 10,871 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.