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Measure SSR hydration timing and issues. Use when tracking hydration performance, debugging hydration mismatches, or optimizing SSR/SSG applications.
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SOC 職業分類に基づく
Instrument API requests with spans and distributed tracing. Use when tracking request latency or debugging API issues.
Monitor JavaScript bundle size and execution performance. Use when tracking bundle size, identifying large chunks, or optimizing load performance.
Measure and optimize Core Web Vitals (LCP, INP, CLS). Use when implementing CWV tracking or debugging performance.
Set up error tracking with actionable context. Use when configuring error capture or error boundaries.
Plan what to measure in web applications. Use when starting observability or prioritizing instrumentation.
Measure time from navigation to page fully loaded and interactive. Use when tracking SPA navigation, route changes, or slow page transitions.
| name | hydration-performance |
| description | Measure SSR hydration timing and issues. Use when tracking hydration performance, debugging hydration mismatches, or optimizing SSR/SSG applications. |
| triggers | ["hydration performance","hydration timing","hydration mismatch","SSR performance","time to interactive","server rendering"] |
| priority | 2 |
Measure the transition from server-rendered HTML to interactive client application.
Server HTML → JavaScript Load → Hydration → Interactive
|_______________________________|
Hydration Timeline
| Metric | Description | Good | Poor |
|---|---|---|---|
| TTH | Time to Hydration | <1s | >3s |
| Hydration Duration | JS execution time | <200ms | >1s |
| TTI | Time to Interactive | <3s | >7s |
// app/providers.tsx
'use client';
import { useEffect, useRef, useState } from 'react';
export function HydrationTracker({ children }: { children: React.ReactNode }) {
const [isHydrated, setIsHydrated] = useState(false);
const hydrationStart = useRef<number>();
useEffect(() => {
// Component mounted = hydration complete
const hydrationEnd = performance.now();
setIsHydrated(true);
// Get navigation timing
const navigation = performance.getEntriesByType('navigation')[0] as PerformanceNavigationTiming;
trackHydration({
hydration_duration_ms: hydrationEnd - (hydrationStart.current || navigation.responseEnd),
time_to_interactive_ms: hydrationEnd - navigation.fetchStart,
dom_content_loaded_ms: navigation.domContentLoadedEventEnd - navigation.fetchStart,
document_complete_ms: navigation.loadEventEnd - navigation.fetchStart,
});
}, []);
// Mark hydration start (runs during SSR, captured in HTML)
if (typeof window === 'undefined') {
return children;
}
if (!hydrationStart.current) {
hydrationStart.current = performance.now();
}
return children;
}
// plugins/hydration.client.ts
export default defineNuxtPlugin((nuxtApp) => {
const hydrationStart = performance.now();
nuxtApp.hook('app:mounted', () => {
const hydrationEnd = performance.now();
trackHydration({
hydration_duration_ms: hydrationEnd - hydrationStart,
route: useRoute().path,
});
});
// Track hydration errors
nuxtApp.hook('app:error', (error) => {
if (error.message?.includes('hydration')) {
trackHydrationError({
error_message: error.message,
route: useRoute().path,
});
}
});
});
<!-- src/routes/+layout.svelte -->
<script lang="ts">
import { onMount } from 'svelte';
import { browser } from '$app/environment';
import { page } from '$app/stores';
let hydrationStart: number;
if (browser) {
hydrationStart = performance.now();
}
onMount(() => {
const hydrationEnd = performance.now();
trackHydration({
hydration_duration_ms: hydrationEnd - hydrationStart,
route: $page.route.id,
});
});
</script>
<slot />
// app/root.tsx
import { useEffect, useRef } from 'react';
import { useLocation } from '@remix-run/react';
function HydrationTracker() {
const location = useLocation();
const hydrationStart = useRef(performance.now());
const hasTracked = useRef(false);
useEffect(() => {
if (!hasTracked.current) {
const hydrationEnd = performance.now();
trackHydration({
hydration_duration_ms: hydrationEnd - hydrationStart.current,
route: location.pathname,
});
hasTracked.current = true;
}
}, []);
return null;
}
export default function App() {
return (
<html>
<head>
<Meta />
<Links />
</head>
<body>
<HydrationTracker />
<Outlet />
<Scripts />
</body>
</html>
);
}
// Capture hydration mismatch errors
function setupHydrationErrorTracking() {
const originalError = console.error;
console.error = (...args) => {
const message = args.join(' ');
// React hydration mismatch
if (
message.includes('Hydration failed') ||
message.includes('Text content does not match') ||
message.includes('did not match')
) {
captureHydrationError({
type: 'hydration_mismatch',
message: message.slice(0, 500),
route: window.location.pathname,
});
}
originalError.apply(console, args);
};
}
For frameworks with partial hydration (Astro, Qwik):
// Astro - track island hydration
// src/components/TrackedIsland.astro
---
const componentName = Astro.props.name;
---
<div
data-island={componentName}
data-hydration-start={Date.now()}
>
<slot />
</div>
<script>
// Track when island becomes interactive
const islands = document.querySelectorAll('[data-island]');
islands.forEach((island) => {
const observer = new MutationObserver(() => {
const start = parseInt(island.dataset.hydrationStart || '0');
const duration = Date.now() - start;
trackIslandHydration({
island_name: island.dataset.island,
hydration_duration_ms: duration,
});
observer.disconnect();
});
observer.observe(island, { childList: true, subtree: true });
});
</script>
| Issue | Cause | Fix |
|---|---|---|
| Long hydration | Large JS bundle | Code split, lazy load |
| Mismatch errors | Server/client divergence | Use useEffect for client-only |
| Layout shift | Hydration changes DOM | Reserve space, skeleton |
| Slow TTI | Blocking hydration | Progressive/selective hydration |
skills/core-web-vitals for LCP during hydrationskills/bundle-performance for JS size impactskills/route-transition-tracking for navigation after hydrationreferences/frameworks/nextjs.md - Next.js hydration patternsreferences/frameworks/nuxt.md - Nuxt hydration patternsreferences/performance.md - Performance budgets