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Fix: Improve useIsMobile SSR and initial render consistency #126

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fehranbit merged 1 commit into from
Dec 11, 2025
Merged

Fix: Improve useIsMobile SSR and initial render consistency #126

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9 changes: 6 additions & 3 deletions src/hooks/use-mobile.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,12 @@ import * as React from 'react';
const MOBILE_BREAKPOINT = 768;

export function useIsMobile() {
const [isMobile, setIsMobile] = React.useState<boolean>(false);
const [isMobile, setIsMobile] = React.useState<boolean>(() => {
if (typeof window === 'undefined') {
return false; // Default for SSR
}
return window.innerWidth < MOBILE_BREAKPOINT; // Initial value for client
});
Comment on lines +6 to +11
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@coderabbitai coderabbitai bot Dec 11, 2025

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⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

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cat -n src/hooks/use-mobile.ts

Repository: Authormaton/authormaton

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rg -n "useIsMobile" --type=ts --type=tsx -C3

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rg -n "useIsMobile" -C3

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sed -n '55,80p' src/components/ui/sidebar.tsx

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sed -n '14,40p' src/components/models/projects/ProjectsTable.tsx

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sed -n '14,60p' src/components/models/projects/ProjectsTable.tsx

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rg -n "suppressHydrationWarning" --type=ts

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rg -n "suppressHydrationWarning"

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Hydration mismatch from lazy useState initializer reading window

The lazy initializer with typeof window === 'undefined' is runtime-safe for SSR, but it causes server and initial client renders to diverge:

  • On the server, isMobile is always false.
  • On the client during hydration, the initializer may return true if innerWidth < 768.

This causes hydration mismatches in components that conditionally render based on isMobile:

  • GeneralLayout.tsx renders <Sheet> on mobile but <div> on desktop based on this value
  • ProjectsTable.tsx renders a grid on mobile but <BasicTable> on desktop based on this value

Both components will render different markup on the server versus the client, triggering hydration warnings and potential layout shifts after the effect updates.

Initialize to a constant value (e.g., useState(false)) and rely on the effect to update after mount, ensuring server and first hydration render are consistent. Alternatively, make these components client-only or add suppressHydrationWarning if the brief mismatch is acceptable.

🤖 Prompt for AI Agents 
In src/hooks/use-mobile.ts around lines 6 to 11, the lazy useState initializer
reads window causing server vs initial client render divergence; change the
initial state to a constant (e.g., useState(false)) so SSR and first hydration
produce the same output, then in a useEffect run only on mount to read
window.innerWidth and setIsMobile accordingly, and also add a resize listener
inside that effect to update on viewport changes with proper cleanup on unmount.


React.useEffect(() => {
if (typeof window === 'undefined') {
Expand All @@ -14,8 +19,6 @@ export function useIsMobile() {
setIsMobile(window.innerWidth < MOBILE_BREAKPOINT);
};

checkIsMobile(); // Set initial value

const resizeObserver = new ResizeObserver(() => {
checkIsMobile();
});
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