React · Hooks (Comprehensive)

useDeferredValue Hook

Master useDeferredValue for optimal UI performance - the essential hook for deferring expensive updates while keeping your app responsive and smooth.

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What is useDeferredValue?

Defer non-critical UI updates for better performance

useDeferredValue is a Hook that lets you defer updating a part of the UI. It creates a delayed version of a value that React can update later, keeping urgent updates responsive and preventing UI freezing!

Basic Syntax

const deferredValue = useDeferredValue(value);

value:The value you want to defer (can be any type)

deferredValue:Delayed version that updates later during render

Performance Boost

• Prevents UI blocking during heavy updates
• Allows urgent updates to take priority
• Reduces unnecessary re-renders
• Maintains smooth user interactions

Use Cases

• Search result filtering
• Large list rendering
• Data visualization updates
• Real-time data streams

Key Advantage!

Unlike regular state, deferred values don't block the UI - React can update them when it has time, keeping your app feeling fast!

Why useDeferredValue is Powerful

Understanding deferred rendering

Immediate vs Deferred Updates

❌ Immediate Update

UI blocks during expensive operations

const filtered = expensiveFilter(searchQuery);

<List data={filtered} /> // UI freezes here

✅ Deferred Update

UI stays responsive, updates when possible

const deferredQuery = useDeferredValue(searchQuery);

const filtered = expensiveFilter(deferredQuery);

<List data={filtered} /> // Non-blocking

⚡ Concurrent Rendering Benefits

With useDeferredValue, React can:

• Delay expensive updates until the browser is idle
• Show stale content while new content prepares
• Interrupt deferred updates with more urgent ones
• Maintain 60fps during heavy operations

Step-by-Step Guide

Learn useDeferredValue progressively

Step 1: Import and Create Deferred Value

First, import useDeferredValue and create a deferred version of your state value that you want to optimize.

//Import and create deferred value

import {} useDeferredValue {} from 'react';

const [searchQuery, setSearchQuery] = useState('');

const deferredQuery = useDeferredValue(searchQuery);

Two Values

searchQuery updates immediately, deferredQuery updates when React has time.

Step 2: Use Deferred Value in Expensive Operations

Use the deferred value in expensive operations like filtering large lists or complex calculations.

//Use deferred value in expensive operations

const filteredItems = useMemo(() => {}

return expensiveFilter(items, deferredQuery);

}, [items, deferredQuery]); // Uses deferred value

Performance Boost

Expensive filtering uses deferred value, keeping UI responsive!

Step 3: Use Immediate Value for Responsive UI

Use the immediate value for responsive UI elements like input fields, while deferred value powers expensive displays.

//Use immediate value for responsive UI

return (

<div>

<input

value={}searchQuery{} // Immediate - responsive

onChange={}(e) => setSearchQuery(e.target.value)}

</div>

);

Best of Both Worlds

Input stays responsive, list updates when possible!

Step 4: Add Loading States (Optional)

Show loading states when deferred value is stale to provide visual feedback about pending updates.

//Add loading state for stale deferred value

const isStale = searchQuery !== deferredQuery;

return (

<div>

{}isStale && <div>Updating...</div>

</div>

);

Visual Feedback

Show users when updates are pending for better UX!

Interactive Example

See useDeferredValue in action

Responsive Search with Deferred Value

Experience smooth filtering without UI freezing

Frontend

function DeferredSearchExample() {
  const [searchQuery, setSearchQuery] = React.useState('');
  const [items] = React.useState(() => {
    // Generate 1000 items for realistic performance test
    return Array.from({ length: 1000 }, (_, i) => ({
      id: i,
      name: `Item ${i + 1}`,
      category: ['Electronics', 'Books', 'Clothing', 'Food', 'Toys'][i % 5],
      price: Math.floor(Math.random() * 1000) + 10
    }));
  });

  // Create deferred version of search query
  const deferredQuery = React.useDeferredValue(searchQuery);
  
  // Check if deferred value is stale
  const isStale = searchQuery !== deferredQuery;

  // Expensive filtering operation (simulated)
  const filteredItems = React.useMemo(() => {
    console.log('Filtering items with query:', deferredQuery);
    
    // Simulate expensive operation
    const start = Date.now();
    while (Date.now() - start < 100) {} // 100ms delay
    
    if (!deferredQuery) return items;
    
    return items.filter(item => 
      item.name.toLowerCase().includes(deferredQuery.toLowerCase()) ||
      item.category.toLowerCase().includes(deferredQuery.toLowerCase())
    );
  }, [items, deferredQuery]);

  return (
    <div className="container">
      <h2>Responsive Search with useDeferredValue</h2>
      <p>Try typing quickly - the input stays responsive while filtering happens in background!</p>
      
      <div className="search-section">
        <input
          type="text"
          value={searchQuery}
          onChange={(e) => setSearchQuery(e.target.value)}
          placeholder="Search 1000 items..."
          className="search-input"
        />
        
        <div className="stats">
          <span className="item-count">
            Showing {filteredItems.length} of {items.length} items
          </span>
          {isStale && (
            <span className="stale-indicator">
              Updating...
            </span>
          )}
        </div>
      </div>

      <div className="results-grid">
        {filteredItems.slice(0, 50).map((item) => (
          <div key={item.id} className="item-card">
            <div className="item-name">{item.name}</div>
            <div className="item-category">{item.category}</div>
            <div className="item-price">{'{'}item.price{'}'}</div>
          </div>
        ))}
      </div>
      
      {filteredItems.length > 50 && (
        <div className="more-items">
          ... and {filteredItems.length - 50} more items
        </div>
      )}
    </div>
  );
}

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<DeferredSearchExample />);

Live Preview

Loading preview...

When to Use useDeferredValue

Practical use cases and best practices

✅ Perfect For

🔍 Large Dataset Filtering

Search/filter operations on thousands of items that would normally block UI

📊 Data Visualization

Charts and graphs that need time to recalculate with new data

📝 Text Processing

Real-time text analysis, syntax highlighting, or markdown parsing

❌ Avoid For

⚡ Simple State

Basic state changes that don't impact performance

🎯 Critical Updates

User input values or anything needing immediate visual feedback

🔄 Network Requests

Use useEffect with loading states for API calls instead

Performance First!

Only use useDeferredValue when you have actual performance issues. Don't over-optimize!

Key Takeaways

Essential useDeferredValue concepts to remember

Deferred Updates

Deferred values update when React has time, not immediately like regular state.

UI Responsiveness

Keeps user interfaces responsive during expensive operations.

Two Values

Keep immediate value for responsive UI, deferred value for expensive operations.

Concurrent Ready

Works with React's concurrent features for optimal performance.

Pro Tip

Combine useDeferredValue with useMemo for the best performance - defer the value, then memoize the expensive operation!

Previous Topic

useTransition Hook

Non-urgent state updates, startTransition, isPending, and improving UI responsiveness.

Next Topic

useImperativeHandle

Customize ref exposure, imperative APIs, and parent-child component communication.

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React · Hooks (Comprehensive)

useDeferredValue Hook

Master useDeferredValue for optimal UI performance - the essential hook for deferring expensive updates while keeping your app responsive and smooth.

Find videos you like?

Save to resource drawer for future reference!

What is useDeferredValue?

Defer non-critical UI updates for better performance

Basic Syntax

const deferredValue = useDeferredValue(value);

value:The value you want to defer (can be any type)

deferredValue:Delayed version that updates later during render

Performance Boost

• Prevents UI blocking during heavy updates
• Allows urgent updates to take priority
• Reduces unnecessary re-renders
• Maintains smooth user interactions

Use Cases

• Search result filtering
• Large list rendering
• Data visualization updates
• Real-time data streams

Key Advantage!

Unlike regular state, deferred values don't block the UI - React can update them when it has time, keeping your app feeling fast!

Why useDeferredValue is Powerful

Understanding deferred rendering

Immediate vs Deferred Updates

❌ Immediate Update

UI blocks during expensive operations

const filtered = expensiveFilter(searchQuery);

<List data={filtered} /> // UI freezes here

✅ Deferred Update

UI stays responsive, updates when possible

const deferredQuery = useDeferredValue(searchQuery);

const filtered = expensiveFilter(deferredQuery);

<List data={filtered} /> // Non-blocking

⚡ Concurrent Rendering Benefits

With useDeferredValue, React can:

• Delay expensive updates until the browser is idle
• Show stale content while new content prepares
• Interrupt deferred updates with more urgent ones
• Maintain 60fps during heavy operations

Step-by-Step Guide

Learn useDeferredValue progressively

Step 1: Import and Create Deferred Value

First, import useDeferredValue and create a deferred version of your state value that you want to optimize.

//Import and create deferred value

import {} useDeferredValue {} from 'react';

const [searchQuery, setSearchQuery] = useState('');

const deferredQuery = useDeferredValue(searchQuery);

Two Values

searchQuery updates immediately, deferredQuery updates when React has time.

Step 2: Use Deferred Value in Expensive Operations

Use the deferred value in expensive operations like filtering large lists or complex calculations.

//Use deferred value in expensive operations

const filteredItems = useMemo(() => {}

return expensiveFilter(items, deferredQuery);

}, [items, deferredQuery]); // Uses deferred value

Performance Boost

Expensive filtering uses deferred value, keeping UI responsive!

Step 3: Use Immediate Value for Responsive UI

Use the immediate value for responsive UI elements like input fields, while deferred value powers expensive displays.

//Use immediate value for responsive UI

return (

<div>

<input

value={}searchQuery{} // Immediate - responsive

onChange={}(e) => setSearchQuery(e.target.value)}

</div>

);

Best of Both Worlds

Input stays responsive, list updates when possible!

Step 4: Add Loading States (Optional)

Show loading states when deferred value is stale to provide visual feedback about pending updates.

//Add loading state for stale deferred value

const isStale = searchQuery !== deferredQuery;

return (

<div>

{}isStale && <div>Updating...</div>

</div>

);

Visual Feedback

Show users when updates are pending for better UX!

Interactive Example

See useDeferredValue in action

Responsive Search with Deferred Value

Experience smooth filtering without UI freezing

Frontend

function DeferredSearchExample() {
  const [searchQuery, setSearchQuery] = React.useState('');
  const [items] = React.useState(() => {
    // Generate 1000 items for realistic performance test
    return Array.from({ length: 1000 }, (_, i) => ({
      id: i,
      name: `Item ${i + 1}`,
      category: ['Electronics', 'Books', 'Clothing', 'Food', 'Toys'][i % 5],
      price: Math.floor(Math.random() * 1000) + 10
    }));
  });

  // Create deferred version of search query
  const deferredQuery = React.useDeferredValue(searchQuery);
  
  // Check if deferred value is stale
  const isStale = searchQuery !== deferredQuery;

  // Expensive filtering operation (simulated)
  const filteredItems = React.useMemo(() => {
    console.log('Filtering items with query:', deferredQuery);
    
    // Simulate expensive operation
    const start = Date.now();
    while (Date.now() - start < 100) {} // 100ms delay
    
    if (!deferredQuery) return items;
    
    return items.filter(item => 
      item.name.toLowerCase().includes(deferredQuery.toLowerCase()) ||
      item.category.toLowerCase().includes(deferredQuery.toLowerCase())
    );
  }, [items, deferredQuery]);

  return (
    <div className="container">
      <h2>Responsive Search with useDeferredValue</h2>
      <p>Try typing quickly - the input stays responsive while filtering happens in background!</p>
      
      <div className="search-section">
        <input
          type="text"
          value={searchQuery}
          onChange={(e) => setSearchQuery(e.target.value)}
          placeholder="Search 1000 items..."
          className="search-input"
        />
        
        <div className="stats">
          <span className="item-count">
            Showing {filteredItems.length} of {items.length} items
          </span>
          {isStale && (
            <span className="stale-indicator">
              Updating...
            </span>
          )}
        </div>
      </div>

      <div className="results-grid">
        {filteredItems.slice(0, 50).map((item) => (
          <div key={item.id} className="item-card">
            <div className="item-name">{item.name}</div>
            <div className="item-category">{item.category}</div>
            <div className="item-price">{'{'}item.price{'}'}</div>
          </div>
        ))}
      </div>
      
      {filteredItems.length > 50 && (
        <div className="more-items">
          ... and {filteredItems.length - 50} more items
        </div>
      )}
    </div>
  );
}

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<DeferredSearchExample />);

Live Preview

Loading preview...

When to Use useDeferredValue

Practical use cases and best practices

✅ Perfect For

🔍 Large Dataset Filtering

Search/filter operations on thousands of items that would normally block UI

📊 Data Visualization

Charts and graphs that need time to recalculate with new data

📝 Text Processing

Real-time text analysis, syntax highlighting, or markdown parsing

❌ Avoid For

⚡ Simple State

Basic state changes that don't impact performance

🎯 Critical Updates

User input values or anything needing immediate visual feedback

🔄 Network Requests

Use useEffect with loading states for API calls instead

Performance First!

Only use useDeferredValue when you have actual performance issues. Don't over-optimize!

Key Takeaways

Essential useDeferredValue concepts to remember

Deferred Updates

Deferred values update when React has time, not immediately like regular state.

UI Responsiveness

Keeps user interfaces responsive during expensive operations.

Two Values

Keep immediate value for responsive UI, deferred value for expensive operations.

Concurrent Ready

Works with React's concurrent features for optimal performance.

Pro Tip

Combine useDeferredValue with useMemo for the best performance - defer the value, then memoize the expensive operation!

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useTransition Hook

useImperativeHandle

Building Your Learning Module...

useDeferredValue Hook

Basic Syntax

Performance Boost

Use Cases

Key Advantage!

Immediate vs Deferred Updates

❌ Immediate Update

✅ Deferred Update

⚡ Concurrent Rendering Benefits

Step 1: Import and Create Deferred Value

Step 2: Use Deferred Value in Expensive Operations

Step 3: Use Immediate Value for Responsive UI

Step 4: Add Loading States (Optional)

Responsive Search with Deferred Value

✅ Perfect For

🔍 Large Dataset Filtering

📊 Data Visualization

📝 Text Processing

❌ Avoid For

⚡ Simple State

🎯 Critical Updates

🔄 Network Requests

Performance First!

Deferred Updates

UI Responsiveness

Two Values

Concurrent Ready

Pro Tip

useTransition Hook

useImperativeHandle

useDeferredValue Hook

Basic Syntax

Performance Boost

Use Cases

Key Advantage!

Immediate vs Deferred Updates

❌ Immediate Update

✅ Deferred Update

⚡ Concurrent Rendering Benefits

Step 1: Import and Create Deferred Value

Step 2: Use Deferred Value in Expensive Operations

Step 3: Use Immediate Value for Responsive UI

Step 4: Add Loading States (Optional)

Responsive Search with Deferred Value

✅ Perfect For

🔍 Large Dataset Filtering

📊 Data Visualization

📝 Text Processing

❌ Avoid For

⚡ Simple State

🎯 Critical Updates

🔄 Network Requests

Performance First!

Deferred Updates

UI Responsiveness

Two Values

Concurrent Ready

Pro Tip