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useWindowSize

Tracks browser window dimensions with automatic updates on resize events. This hook subscribes to window resize events and provides real-time viewport dimensions, enabling responsive components that adapt to window size changes. It handles event listener cleanup automatically and provides initial size measurement after component mount.

Use Cases​

  • Responsive Components: Adapt layout based on current viewport size
  • Conditional Rendering: Show/hide elements based on available screen space
  • Dynamic Calculations: Calculate dimensions relative to viewport (e.g., modals, overlays)
  • Breakpoint Logic: Implement custom responsive breakpoints in JavaScript
  • Performance Optimization: Render different components for mobile vs desktop
  • Accessibility: Adjust UI density and touch targets based on screen size

Performance Considerations​

  • High Frequency Events: Resize events fire frequently during window resizing
  • Debouncing Recommended: For expensive computations, combine with useDebounce
  • SSR Compatibility: Returns {width: 0, height: 0} on server-side
  • Memory Efficiency: Automatically cleans up event listeners on unmount

Responsive Design Patterns​

Use this hook to implement responsive behavior that CSS media queries can't handle:

  • Dynamic grid columns based on available width
  • Conditional component rendering
  • Viewport-aware animations and transitions
  • Content sizing relative to viewport

Signature​

const useWindowSize: () => {
    width: number;
    height: number;
}

Returns​

An object containing the current window dimensions: - width: The inner width of the window in pixels (0 during SSR) - height: The inner height of the window in pixels (0 during SSR)

Examples​

Example 1​

// Basic responsive layout switching
const ResponsiveLayout = () => {
  const { width, height } = useWindowSize();

  const isMobile = width < 768;
  const isTablet = width >= 768 && width < 1024;
  const isDesktop = width >= 1024;

  // Content area sized to viewport
  return (
    <div className={`layout ${isMobile ? 'mobile' : isTablet ? 'tablet' : 'desktop'}`}>
      {isMobile ? (
        <MobileNavigation />
      ) : (
        <DesktopNavigation />
      )}

      <main style={{ minHeight: height - 80 }}>
        <Content />
      </main>
    </div>
  );
};

// Custom breakpoint hook composition
const useBreakpoint = () => {
  const { width } = useWindowSize();

  return useMemo(() => {
    if (width < 480) return 'xs';
    if (width < 768) return 'sm';
    if (width < 1024) return 'md';
    if (width < 1280) return 'lg';
    if (width < 1536) return 'xl';
    return '2xl';
  }, [width]);
};

const AdaptiveComponent = () => {
  const breakpoint = useBreakpoint();

  const config = useMemo(() => {
    switch (breakpoint) {
      case 'xs': return { columns: 1, cardSize: 'small', showSidebar: false };
      case 'sm': return { columns: 2, cardSize: 'small', showSidebar: false };
      case 'md': return { columns: 2, cardSize: 'medium', showSidebar: true };
      case 'lg': return { columns: 3, cardSize: 'medium', showSidebar: true };
      default: return { columns: 4, cardSize: 'large', showSidebar: true };
    }
  }, [breakpoint]);

  return (
    <div className={`responsive-grid grid-${config.columns}`}>
      // Component adapts to breakpoint
    </div>
  );
};

// Dynamic grid with calculated columns
const ResponsiveGrid = ({ items, minItemWidth = 250 }) => {
  const { width } = useWindowSize();

  const columns = Math.max(1, Math.floor(width / minItemWidth));
  const itemWidth = Math.floor((width - (columns + 1) * 20) / columns);

  return (
    <div
      style={{
        display: 'grid',
        gridTemplateColumns: `repeat(${columns}, 1fr)`,
        gap: '20px',
        padding: '20px'
      }}
    >
      {items.map((item, index) => (
        <GridItem
          key={item.id}
          data={item}
          width={itemWidth}
        />
      ))}
    </div>
  );
};

// Viewport-aware modal positioning
const AdaptiveModal = ({ isOpen, onClose, children }) => {
  const { width, height } = useWindowSize();

  const modalStyle = useMemo(() => {
    const isMobile = width < 768;

    if (isMobile) {
      // Full-screen on mobile
      return {
        position: 'fixed',
        top: 0,
        left: 0,
        width: '100%',
        height: '100%',
        transform: 'none'
      };
    } else {
      // Centered with max dimensions on desktop
      const maxWidth = Math.min(800, width * 0.9);
      const maxHeight = Math.min(600, height * 0.8);

      return {
        position: 'fixed',
        top: '50%',
        left: '50%',
        transform: 'translate(-50%, -50%)',
        width: maxWidth,
        height: maxHeight,
        maxWidth: '90vw',
        maxHeight: '90vh'
      };
    }
  }, [width, height]);

  if (!isOpen) return null;

  return (
    <>
      <div className="modal-backdrop" onClick={onClose} />
      <div className="modal" style={modalStyle}>
        {children}
      </div>
    </>
  );
};

// Performance-optimized with debouncing
const DeboucedResponsiveChart = ({ data }) => {
  const windowSize = useWindowSize();

  // Debounce resize events to prevent excessive chart re-renders
  const debouncedSize = useDebounce(() => windowSize, 250);

  const chartDimensions = useMemo(() => {
    const { width, height } = debouncedSize;
    const chartWidth = Math.min(width - 40, 1200);
    const chartHeight = Math.min(height * 0.6, 400);

    return { width: chartWidth, height: chartHeight };
  }, [debouncedSize]);

  return (
    <div className="chart-container">
      <Chart
        data={data}
        width={chartDimensions.width}
        height={chartDimensions.height}
      />
    </div>
  );
};

// Orientation-aware component
const OrientationSensitive = () => {
  const { width, height } = useWindowSize();

  const orientation = width > height ? 'landscape' : 'portrait';
  const aspectRatio = (width / height).toFixed(2);

  return (
    <div className={`app-${orientation}`}>
      <div className="viewport-info">
        <span>Size: {width} × {height}</span>
        <span>Orientation: {orientation}</span>
        <span>Aspect Ratio: {aspectRatio}</span>
      </div>

      {orientation === 'landscape' ? (
        <LandscapeLayout />
      ) : (
        <PortraitLayout />
      )}
    </div>
  );
};

// Fullscreen component with viewport sizing
const FullscreenCanvas = () => {
  const { width, height } = useWindowSize();
  const canvasRef = useRef<HTMLCanvasElement>(null);

  useEffect(() => {
    const canvas = canvasRef.current;
    if (!canvas) return;

    // Update canvas size to match viewport
    canvas.width = width;
    canvas.height = height;

    // Update canvas rendering based on new size
    const ctx = canvas.getContext('2d');
    if (ctx) {
      redrawCanvas(ctx, width, height);
    }
  }, [width, height]);

  return (
    <canvas
      ref={canvasRef}
      style={{
        position: 'fixed',
        top: 0,
        left: 0,
        width: '100vw',
        height: '100vh'
      }}
    />
  );
};

// Responsive text sizing
const ScalingText = ({ children }) => {
  const { width } = useWindowSize();

  const fontSize = useMemo(() => {
    // Scale font size based on viewport width
    const baseSize = 16;
    const scaleFactor = Math.max(0.8, Math.min(1.5, width / 1200));
    return baseSize * scaleFactor;
  }, [width]);

  return (
    <div style={{ fontSize: `${fontSize}px` }}>
      {children}
    </div>
  );
};

// Conditional loading based on screen size
const ConditionalFeatures = () => {
  const { width } = useWindowSize();
  const isLargeScreen = width >= 1200;

  return (
    <div>
      <MainContent />
      // Only load heavy components on large screens
      {isLargeScreen && (
        <Suspense fallback={<div>Loading advanced features...</div>}>
          <AdvancedAnalytics />
          <RealTimeChart />
          <DetailedControls />
        </Suspense>
      )}
    </div>
  );
};

Playground​

// Basic responsive layout switching
const ResponsiveLayout = () => {
const { width, height } = useWindowSize();

const isMobile = width < 768;
const isTablet = width >= 768 && width < 1024;
const isDesktop = width >= 1024;

// Content area sized to viewport
return (
  <div className={`layout ${isMobile ? 'mobile' : isTablet ? 'tablet' : 'desktop'}`}>
    {isMobile ? (
      <MobileNavigation />
    ) : (
      <DesktopNavigation />
    )}

    <main style={{ minHeight: height - 80 }}>
      <Content />
    </main>
  </div>
);
};

// Custom breakpoint hook composition
const useBreakpoint = () => {
const { width } = useWindowSize();

return useMemo(() => {
  if (width < 480) return 'xs';
  if (width < 768) return 'sm';
  if (width < 1024) return 'md';
  if (width < 1280) return 'lg';
  if (width < 1536) return 'xl';
  return '2xl';
}, [width]);
};

const AdaptiveComponent = () => {
const breakpoint = useBreakpoint();

const config = useMemo(() => {
  switch (breakpoint) {
    case 'xs': return { columns: 1, cardSize: 'small', showSidebar: false };
    case 'sm': return { columns: 2, cardSize: 'small', showSidebar: false };
    case 'md': return { columns: 2, cardSize: 'medium', showSidebar: true };
    case 'lg': return { columns: 3, cardSize: 'medium', showSidebar: true };
    default: return { columns: 4, cardSize: 'large', showSidebar: true };
  }
}, [breakpoint]);

return (
  <div className={`responsive-grid grid-${config.columns}`}>
    // Component adapts to breakpoint
  </div>
);
};

// Dynamic grid with calculated columns
const ResponsiveGrid = ({ items, minItemWidth = 250 }) => {
const { width } = useWindowSize();

const columns = Math.max(1, Math.floor(width / minItemWidth));
const itemWidth = Math.floor((width - (columns + 1) * 20) / columns);

return (
  <div
    style={{
      display: 'grid',
      gridTemplateColumns: `repeat(${columns}, 1fr)`,
      gap: '20px',
      padding: '20px'
    }}
  >
    {items.map((item, index) => (
      <GridItem
        key={item.id}
        data={item}
        width={itemWidth}
      />
    ))}
  </div>
);
};

// Viewport-aware modal positioning
const AdaptiveModal = ({ isOpen, onClose, children }) => {
const { width, height } = useWindowSize();

const modalStyle = useMemo(() => {
  const isMobile = width < 768;

  if (isMobile) {
    // Full-screen on mobile
    return {
      position: 'fixed',
      top: 0,
      left: 0,
      width: '100%',
      height: '100%',
      transform: 'none'
    };
  } else {
    // Centered with max dimensions on desktop
    const maxWidth = Math.min(800, width * 0.9);
    const maxHeight = Math.min(600, height * 0.8);

    return {
      position: 'fixed',
      top: '50%',
      left: '50%',
      transform: 'translate(-50%, -50%)',
      width: maxWidth,
      height: maxHeight,
      maxWidth: '90vw',
      maxHeight: '90vh'
    };
  }
}, [width, height]);

if (!isOpen) return null;

return (
  <>
    <div className="modal-backdrop" onClick={onClose} />
    <div className="modal" style={modalStyle}>
      {children}
    </div>
  </>
);
};

// Performance-optimized with debouncing
const DeboucedResponsiveChart = ({ data }) => {
const windowSize = useWindowSize();

// Debounce resize events to prevent excessive chart re-renders
const debouncedSize = useDebounce(() => windowSize, 250);

const chartDimensions = useMemo(() => {
  const { width, height } = debouncedSize;
  const chartWidth = Math.min(width - 40, 1200);
  const chartHeight = Math.min(height * 0.6, 400);

  return { width: chartWidth, height: chartHeight };
}, [debouncedSize]);

return (
  <div className="chart-container">
    <Chart
      data={data}
      width={chartDimensions.width}
      height={chartDimensions.height}
    />
  </div>
);
};

// Orientation-aware component
const OrientationSensitive = () => {
const { width, height } = useWindowSize();

const orientation = width > height ? 'landscape' : 'portrait';
const aspectRatio = (width / height).toFixed(2);

return (
  <div className={`app-${orientation}`}>
    <div className="viewport-info">
      <span>Size: {width} × {height}</span>
      <span>Orientation: {orientation}</span>
      <span>Aspect Ratio: {aspectRatio}</span>
    </div>

    {orientation === 'landscape' ? (
      <LandscapeLayout />
    ) : (
      <PortraitLayout />
    )}
  </div>
);
};

// Fullscreen component with viewport sizing
const FullscreenCanvas = () => {
const { width, height } = useWindowSize();
const canvasRef = useRef<HTMLCanvasElement>(null);

useEffect(() => {
  const canvas = canvasRef.current;
  if (!canvas) return;

  // Update canvas size to match viewport
  canvas.width = width;
  canvas.height = height;

  // Update canvas rendering based on new size
  const ctx = canvas.getContext('2d');
  if (ctx) {
    redrawCanvas(ctx, width, height);
  }
}, [width, height]);

return (
  <canvas
    ref={canvasRef}
    style={{
      position: 'fixed',
      top: 0,
      left: 0,
      width: '100vw',
      height: '100vh'
    }}
  />
);
};

// Responsive text sizing
const ScalingText = ({ children }) => {
const { width } = useWindowSize();

const fontSize = useMemo(() => {
  // Scale font size based on viewport width
  const baseSize = 16;
  const scaleFactor = Math.max(0.8, Math.min(1.5, width / 1200));
  return baseSize * scaleFactor;
}, [width]);

return (
  <div style={{ fontSize: `${fontSize}px` }}>
    {children}
  </div>
);
};

// Conditional loading based on screen size
const ConditionalFeatures = () => {
const { width } = useWindowSize();
const isLargeScreen = width >= 1200;

return (
  <div>
    <MainContent />
    // Only load heavy components on large screens
    {isLargeScreen && (
      <Suspense fallback={<div>Loading advanced features...</div>}>
        <AdvancedAnalytics />
        <RealTimeChart />
        <DetailedControls />
      </Suspense>
    )}
  </div>
);
};