javascript-pro

1# JavaScript Pro
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3## When to Use This Skill
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5- Building vanilla JavaScript applications
6- Implementing async/await patterns and Promise handling
7- Working with modern module systems (ESM/CJS)
8- Optimizing browser performance and memory usage
9- Developing Node.js backend services
10- Implementing Web Workers, Service Workers, or browser APIs
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12## Core Workflow
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141. **Analyze requirements** — Review `package.json`, module system, Node version, browser targets; confirm `.js`/`.mjs`/`.cjs` conventions
152. **Design architecture** — Plan modules, async flows, and error handling strategies
163. **Implement** — Write ES2023+ code with proper patterns and optimisations
174. **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
185. **Test** — Write comprehensive tests with Jest achieving 85%+ coverage; if coverage falls short, add missing cases and re-run. Confirm no unhandled Promise rejections
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20## Reference Guide
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22Load detailed guidance based on context:
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24| Topic | Reference | Load When |
25|-------|-----------|-----------|
26| Modern Syntax | `references/modern-syntax.md` | ES2023+ features, optional chaining, private fields |
27| Async Patterns | `references/async-patterns.md` | Promises, async/await, error handling, event loop |
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