Javascript Pro

This one enforces modern JavaScript standards across ES2023+ projects, with a strong stance on async/await over callbacks and ESM over mixed module systems. It's built for vanilla JS work, Node.js backends, and browser APIs, with a five-step workflow that won't let you proceed past linting or coverage failures until you fix them. The constraint list is opinionated in a good way: no var, no synchronous I/O, no parameter mutation. Includes reference docs for async patterns, modules, and browser APIs. If you're tired of codebases that mix require() with import or skip error handling in async functions, this codifies the discipline to prevent that drift.

skills.sh installs: 6.4K
GitHub stars: 12.3K
last updated: Aug 21, 2026

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Install

$ npx -y skills add jeffallan/claude-skills --skill javascript-pro --agent claude-code

Installs into .claude/skills of the current project.

Files

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

Analyze requirements — Review package.json, module system, Node version, browser targets; confirm .js/.mjs/.cjs conventions
Design architecture — Plan modules, async flows, and error handling strategies
Implement — Write ES2023+ code with proper patterns and optimisations
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
Test — Write comprehensive tests with Jest achieving 85%+ coverage; if coverage falls short, add missing cases and re-run. Confirm no unhandled Promise rejections