Fix/toggle theme hydration error #621
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Uses the isClient state with useEffect to ensure the theme button is only rendered client-side, preventing the SSR/client mismatch when reading user preferences from localStorage.
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WalkthroughAdds a client-side hydration guard to the theme toggle to avoid SSR/CSR mismatches; the Button is rendered only after mount and shows Sun or Moon based on current theme. Header rightContent classes were adjusted to change spacing/centering. No public API changes. Changes
Sequence Diagram(s)sequenceDiagram
autonumber
participant U as User
participant Browser as Browser
participant SSR as Server (SSR)
participant TT as ThemeToggle (Client)
participant Theme as Theme Store
Note over SSR,Browser: Server renders initial HTML without client-only button
Browser->>TT: Load & hydrate
TT->>TT: useEffect -> set isClient = true
TT->>Theme: read current theme (dark/light)
TT-->>Browser: render Button with Sun (if dark) or Moon (if light)
U->>TT: click toggle
TT->>Theme: toggle theme
Theme-->>TT: updated theme
TT-->>Browser: re-render with updated icon
Estimated code review effort🎯 2 (Simple) | ⏱️ ~10 minutes Poem
Pre-merge checks and finishing touches❌ Failed checks (2 warnings)
✅ Passed checks (3 passed)
✨ Finishing touches
🧪 Generate unit tests
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apps/web/src/components/theme-toggle.tsx(1 hunks)
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📓 Path-based instructions (5)
**/*.{jsx,tsx}
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Files:
apps/web/src/components/theme-toggle.tsx
**/*.{ts,tsx}
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**/*.{ts,tsx}: Don't use TypeScript enums.
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Files:
apps/web/src/components/theme-toggle.tsx
**/*.{js,jsx,ts,tsx}
📄 CodeRabbit inference engine (.github/copilot-instructions.md)
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Files:
apps/web/src/components/theme-toggle.tsx
**/*.{tsx,jsx}
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Files:
apps/web/src/components/theme-toggle.tsx
**/*.{ts,tsx,js,jsx}
📄 CodeRabbit inference engine (.cursor/rules/ultracite.mdc)
**/*.{ts,tsx,js,jsx}: Don't use the comma operator
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Files:
apps/web/src/components/theme-toggle.tsx
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Thanks this it is fix my problem too #618 |
2 participants
fix: prevent hydration error in ThemeToggle (Fixes #610)
Description
This PR resolves a React hydration mismatch error that occurs during initial page load when rendering the ThemeToggle component.
The issue occurred because the theme context (useTheme from next-themes) attempted to read from localStorage during the first render. Since localStorage is only available in the browser, the server-rendered HTML mismatched the client-rendered output, causing hydration errors.
Technical Solution
Implemented the “wait until mounted” pattern in ThemeToggle.tsx:
Added const [isClient, setIsClient] = useState(false).
Used useEffect to update setIsClient(true) after the component mounts.
Conditionally rendered the theme toggle button:
{isClient && ...}
Ensures the button and theme icons only render on the client, eliminating hydration errors.
Motivation and Context
Prevents hydration warnings/errors in the console.
Ensures a smoother user experience without flicker or mismatched UI.
Improves code clarity by explicitly separating SSR and client-only logic.
Screenshots
Before (hydration error present):
After (hydration fixed):
and there was bug in the responsiveness of navbar which was overflowing on 320px
which was fixed
Before
After
Type of Change
Bug fix (non-breaking change which fixes an issue)
Code refactoring
How Has This Been Tested?
Steps to Reproduce & Verify Fix:
Run bun run dev.
Open the app in browser.
Perform a hard refresh (Ctrl/Cmd + Shift + R).
✅ Verify that no hydration errors (Hydration failed / Expected server HTML…) appear in the console.
✅ Confirm that the theme toggle button appears and works (light ↔ dark mode).
Test Environment:
Node.js: [v22.14.0]
Browser: [Brave 1.8.12]
OS: [Windows]
Checklist
My code follows the project style guidelines
Self-reviewed my code
Added screenshots if UI has changed
Commented code where necessary
Updated documentation if needed
No new warnings introduced
Verified fix with manual console check
Existing tests pass locally
Summary by CodeRabbit
New Features
Bug Fixes
Style
Accessibility