What is useDeferredValue in React: Explanation and Example

useDeferredValue is a React hook that lets you delay updating a value to keep your app responsive during heavy rendering. It returns a deferred version of a value that updates less urgently, helping avoid UI freezes when input changes fast.

How It Works

useDeferredValue works like a traffic controller for your app's updates. Imagine you are typing in a search box, and the app shows results as you type. Without deferring, the app tries to update results immediately on every keystroke, which can slow things down.

With useDeferredValue, React keeps showing the old results while it waits to update the new ones. It delays the update just enough so the app stays smooth and responsive, like letting some cars pass before others at a busy intersection.

This hook is useful when you want to keep the UI fast and avoid blocking user input, especially during expensive rendering tasks.

Example

This example shows a text input where the displayed deferred value updates slower than the typed input, keeping the UI responsive.

react

import React, { useState, useDeferredValue } from 'react';

export default function DeferredValueExample() {
  const [text, setText] = useState('');
  const deferredText = useDeferredValue(text);

  return (
    <div style={{ fontFamily: 'Arial, sans-serif', padding: '1rem' }}>
      <label htmlFor="input" style={{ display: 'block', marginBottom: '0.5rem' }}>
        Type something:
      </label>
      <input
        id="input"
        type="text"
        value={text}
        onChange={e => setText(e.target.value)}
        style={{ padding: '0.5rem', fontSize: '1rem', width: '100%', maxWidth: '300px' }}
        aria-label="Type text input"
      />
      <p style={{ marginTop: '1rem' }}>
        Immediate value: <strong>{text}</strong>
      </p>
      <p>
        Deferred value: <strong>{deferredText}</strong>
      </p>
    </div>
  );
}

Output

A text input box with two lines below showing "Immediate value:" updating instantly as you type and "Deferred value:" updating slightly slower, keeping the UI smooth.

When to Use

Use useDeferredValue when you have a fast-changing value that triggers heavy rendering or slow updates, like filtering large lists or complex UI updates. It helps keep the app responsive by delaying less urgent updates.

For example, in a search input filtering thousands of items, you can defer the filtered results update so typing stays smooth. Another case is when you want to prioritize user input over rendering complex components.

Key Points

• useDeferredValue delays updating a value to keep UI responsive.
• It returns a deferred version of the input value that updates less urgently.
• Helps avoid blocking user input during expensive rendering.
• Useful for search inputs, filtering, or complex UI updates.
• Works well with React 18 and newer versions.

Key Takeaways

useDeferredValue helps keep React apps responsive by delaying less urgent updates.

It returns a deferred value that updates slower than the original input.

Use it when rendering is slow or input changes rapidly, like in search or filtering.

It improves user experience by prioritizing immediate input over heavy rendering.

Requires React 18 or newer to work.