Chrome DevTools Auto Analyzer

## When to Use User wants to automatically analyze a website URL for performance metrics, accessibility, SEO, or best practices without manual Chrome DevTools interaction. ## Core Rules 1. **Verify prerequisites** — Check Node.js (v18+) and packages installed: `node --version && npm list lighthouse chrome-launcher` 2. **Run Lighthouse audit** — Execute `node automation-script.js <URL> [--mobile] [--output=DIR]` to collect all metrics. 3. **Extract and present metrics** — Use tables for scores (0-100) and metrics with status indicators (⚪ Good, 🟡 Warning, 🔴 Critical). 4. **Identify critical issues** — Flag metrics outside thresholds: LCP>2.5s, CLS>0.1, INP>200ms, TBT>200ms, Performance<50. 5. **Provide actionable fixes** — For each issue, include specific code fixes from `audit-checklist.md` and `metrics-reference.md`. 6. **Save results** — Store JSON and HTML reports in `./results/`. Ask user before saving to memory for tracking. 7. **Handle errors gracefully** — If audit fails, check `troubleshooting.md` for common solutions (Chrome not found, ES module errors, memory issues). ## Quick Reference | Topic | File | |-------|------| | Automation script | `automation-script.js` | | Metrics & thresholds | `metrics-reference.md` | | Fix checklists | `audit-checklist.md` | | Setup guide | `setup.md` | | Quick start | `quick-start.md` | | Troubleshooting | `troubleshooting.md` | | Memory tracking | `memory-template.md` | ## Data Storage After analysis, offer to save: URL, timestamp, scores, critical issues, report path. Always ask before saving to memory. ## Security & Privacy - Runs locally in headless Chrome — no external data transmission - Warn before analyzing authenticated URLs - JSON reports contain URL structure — handle sensitive paths carefully ## Common Commands ```bash # Quick audit (desktop) node automation-script.js https://example.com # Mobile emulation node automation-script.js https://example.com --mobile # Custom output directory node automation-script.js https://example.com --output=./reports # Lighthouse CLI directly lighthouse https://example.com --output=json --output-path=report.json ``` ## Troubleshooting Quick Reference | Error | Solution | |-------|----------| | "lighthouse is not a function" | Add `"type": "module"` to package.json | | "Chrome not found" | Install Chrome or use `npm install puppeteer` | | "JavaScript heap out of memory" | Run with `node --max-old-space-size=4096` | | "Port already in use" | Specify different port in script config |