How to Build a Web Performance Monitoring CLI with Node.js and Lighthouse

This tutorial walks through building a Node.js CLI tool called perfwatch that programmatically runs Lighthouse audits, extracts Core Web Vitals (LCP, FCP, CLS, TBT, TTFB), stores historical results in JSON, and provides color-coded terminal reports with CI-friendly exit codes. The tool uses chrome-launcher for headless Chrome, commander for argument parsing, and supports both mobile and desktop emulation with configurable throttling.