Website Speed & Performance Optimization

const domain = 'staging.example.com';
const headers = { 'Authorization': 'Bearer YOUR_API_KEY' };

const [compression, cache, httpVersion, pageWeight, score, readiness] = await Promise.all([
  fetch(`https://api.edgedns.dev/v1/domain/compression?domain=${domain}`, { headers }),
  fetch(`https://api.edgedns.dev/v1/domain/cache?domain=${domain}`, { headers }),
  fetch(`https://api.edgedns.dev/v1/domain/http-version?domain=${domain}`, { headers }),
  fetch(`https://api.edgedns.dev/v1/domain/page-weight?domain=${domain}`, { headers }),
  fetch(`https://api.edgedns.dev/v1/score/performance?domain=${domain}`, { headers }),
  fetch(`https://api.edgedns.dev/v1/domain/search-readiness?domain=${domain}`, { headers }),
].map(p => p.then(r => r.json())));

const issues = [];

// Compression — recognize zstd alongside gzip/brotli
if (!compression.data.isCompressed) issues.push('Compression disabled');

// Cache — flag broken ETag validation (origin sets ETag but ignores If-None-Match)
if (!cache.data.isCacheable) issues.push('Response not cacheable');
if (cache.data.etag && cache.data.etagValidates === false) issues.push('ETag set but does not return 304');

// HTTP version — require DNS-confirmed HTTP/2 (HTTPS RR), not just "inferred"
if (httpVersion.data.http2Confidence === 'inferred') {
  issues.push('HTTP/2 not DNS-confirmed — publish an HTTPS DNS record with alpn=h2,h3');
}

// Page weight — enforce budget AND flag uncompressed assets / heavy third parties
if (pageWeight.data.totalSizeBytes > 2_000_000) issues.push('Page exceeds 2MB budget');
const thirdPartyPct = pageWeight.data.byOrigin
  ?.filter((o) => o.isThirdParty)
  .reduce((s, o) => s + o.percentage, 0) ?? 0;
if (thirdPartyPct >= 50) issues.push(`Third-party assets are ${thirdPartyPct.toFixed(0)}% of page weight`);
if (pageWeight.data.imageFormatAudit?.length > 0) {
  issues.push(`${pageWeight.data.imageFormatAudit.length} large images could move to AVIF/WebP`);
}

// Score — synthetic floor + CrUX field-data overlay
if (score.data.score < 80) issues.push(`Performance score is ${score.data.score} (target ≥ 80)`);
const lcpP75 = score.data.cwv?.byFormFactor?.all?.lcp?.value;
if (lcpP75 && lcpP75 > 2500) issues.push(`Real-user LCP p75 is ${Math.round(lcpP75)}ms (CWV threshold: 2500ms)`);

// Search-readiness regressions
if (readiness.data.softFourOhFour?.detected) issues.push('Soft 404 detected on homepage');
if ((readiness.data.mixedContent?.issues?.length ?? 0) > 0) issues.push('Mixed content present');
if (!readiness.data.securityHeaders?.hasCsp) issues.push('Missing Content-Security-Policy');

if (issues.length > 0) {
  console.error('Performance gate FAILED:', issues);
  // Sorted recommendations with estimated point impact tell you what to fix first
  console.error('Top fixes:', score.data.recommendationsWithImpact?.slice(0, 3));
  process.exit(1);
}
console.log('Performance gate PASSED — grade', score.data.grade);