| name | lighthouse |
| description | Run Lighthouse audits for performance, accessibility, and best practices scoring. Use when checking page performance, running quality audits, measuring Core Web Vitals, or getting a quantitative quality score for a web page. |
| compatibility | Requires Lighthouse CLI (npm i -g lighthouse) |
| metadata | {"author":"ridgeline","version":"1.0"} |
Lighthouse Audit
Run Google Lighthouse for quantitative quality scores across performance, accessibility, and best practices.
Running an audit
npx lighthouse <url> --output json --output-path ./lighthouse-report.json --only-categories=performance,accessibility,best-practices --chrome-flags="--headless=new --no-sandbox"
For a quick text summary:
npx lighthouse <url> --output html --output-path ./lighthouse-report.html --only-categories=performance,accessibility,best-practices --chrome-flags="--headless=new --no-sandbox"
Reading results
Parse the JSON output to extract category scores:
node -e "
const r = require('./lighthouse-report.json');
const cats = r.categories;
console.log('Performance:', Math.round(cats.performance.score * 100));
console.log('Accessibility:', Math.round(cats.accessibility.score * 100));
console.log('Best Practices:', Math.round(cats['best-practices'].score * 100));
"
Score thresholds
- Performance > 90: Good
- Performance 50–90: Needs improvement
- Performance < 50: Poor
- Accessibility > 90: Good (aim for 100)
- Accessibility < 90: Needs attention
Severity mapping
- Accessibility score < 90 when design.md requires WCAG → blocking
- Performance or best practices concerns → suggestion
- All scores are informational by default — context determines severity
Gotchas
- Lighthouse scores vary between runs (±5 points). Run 3 times and take the median for reliable results.
- Local dev servers often score low on performance due to unminified assets. This is expected.
- Lighthouse requires a running page — start the dev server first.
