how to use useDeferredValue hook explained with example

Great! Let's delve into the useDeferredValue hook in React.

Understanding useDeferredValue

The useDeferredValue hook is part of React's Concurrent Mode features, specifically designed to optimize UI updates for certain interactions, such as text input. It is often used in conjunction with the Suspense component.

The primary use case for useDeferredValue is to delay the update of a value until certain conditions are met. This can be helpful in scenarios where you want to prioritize responsiveness and smooth user interactions.

Example Usage

Let's consider a scenario where you have a search input, and you want to fetch search results from an API in response to user input. You might use useDeferredValue to delay the fetching of results until the user has paused typing.

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

// Simulate an API call to fetch search results
const fetchSearchResults = query => {
  console.log(`Fetching results for: ${query}`);
  // In a real application, this is where you would make an API call
};

// SearchResults component that displays search results
const SearchResults = ({ query }) => {
  // Simulate rendering search results
  return <p>Displaying results for: {query}</p>;
};

// Search component with Suspense and useDeferredValue
const Search = () => {
  const [searchQuery, setSearchQuery] = useState('');
  const deferredQuery = React.useDeferredValue(searchQuery, { timeoutMs: 200 });

  // Simulate a function to handle user input
  const handleInputChange = event => {
    setSearchQuery(event.target.value);
  };

  return (
    <div>
      <input type="text" value={searchQuery} onChange={handleInputChange} />
      
      <Suspense fallback={<p>Loading...</p>}>
        {/* Use the deferred value for fetching results */}
        <SearchResults query={deferredQuery} />
      </Suspense>
    </div>
  );
};

export default Search;

In this example:

• The useDeferredValue hook is applied to the searchQuery. It introduces a delay (timeoutMs: 200) before updating the deferred value.
• The SearchResults component is wrapped in a Suspense component, which allows React to wait for the deferred value to be ready before rendering.

This helps optimize the rendering of the search results by avoiding unnecessary updates while the user is actively typing. The timeoutMs parameter in useDeferredValue sets the delay before the value is considered ready.

Keep in mind that useDeferredValue is part of the Concurrent Mode experimental features in React and may not be suitable for all applications. Always refer to the React documentation for the latest information and best practices.