React useDeferredValue Hook

React is a popular JavaScript library used for building user interfaces. One of its core principles is hooks, which are functions that let you use React state and other features without writing a class. The useDeferredValue hook is a new addition to React, introduced in version 18, that allows you to defer the update of a state value until the next render cycle. In this tutorial, we’ll take a closer look at the useDeferredValue hook and how it can be used in your React applications.

What is the useDeferredValue hook?

The useDeferredValue hook is a React hook that allows you to defer the update of a state value until the next render cycle. This means that when you update a state value using the useDeferredValue hook, React will not immediately update the component with the new value. Instead, React will wait until the next render cycle to update the component. This can help improve the performance of your React application, especially when dealing with expensive computations or rendering large amounts of data.

The useDeferredValue hook takes two arguments: the value you want to update and a configuration object. The configuration object can be used to specify how long you want to defer the update, whether to use a timeout or a Promise, and other options.

Here’s an example of how you can use the useDeferredValue hook in your React application:

import { useState, useDeferredValue } from 'react';

function MyComponent() {
  const [count, setCount] = useState(0);

  const deferredCount = useDeferredValue(count);

  return (
    <div>
      <p>Current count: {deferredCount}</p>
      <button onClick={() => setCount(count + 1)}>Increment count</button>
    </div>
  );
}

In this example, we’re using the useDeferredValue hook to defer the update of the count state value. When the user clicks the “Increment count” button, the count value will be updated, but the component will not immediately re-render. Instead, React will wait until all the urgent updates have been finished before updating the component with the new count value.

Why use the useDeferredValue hook?

There are several reasons why you might want to use the useDeferredValue hook in your React application:

  1. Performance optimization: When dealing with expensive computations or rendering large amounts of data, deferring updates using the useDeferredValue hook can help improve the performance of your application. By waiting until the next render cycle to update the component, you can reduce the number of times your component needs to render and improve the overall performance of your application.
  2. Better user experience: Deferring updates using the useDeferredValue hook can also improve the user experience of your application. Users who interact with your application don’t want to see slow or jerky animations. By deferring updates, you can make your animations smoother and more responsive, improving the overall user experience.
  3. Avoiding unnecessary re-renders: The useDeferredValue hook can also help you avoid unnecessary re-renders in your React application. When you update a state value using setState, React will immediately re-render the component. This can lead to unnecessary re-renders if you’re updating a state value frequently or if the updated value doesn’t change the component’s output. By deferring updates, you can ensure that your component only re-renders when necessary.
  4. Fine-grained control: Finally, the useDeferredValue hook gives you fine-grained control over when and how state updates are applied. By specifying a timeout or a Promise, you can control when the update is applied and specify other options to customize the behaviour of the useDeferredValue hook.

How to use the useDeferredValue hook

Besides the example above, you can also use the useDeferredValue hook with other hooks, such as useEffect and useMemo. Here’s an example of how you can use the useDeferredValue hook with the useEffect hook:

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

function MyComponent() {
  const [count, setCount] = useState(0);

  const deferredCount = useDeferredValue(count);

  useEffect(() => {
    // Perform some expensive computation using the deferredCount value
    // ...
  }, [deferredCount]);

  return (
    <div>
      <p>Current count: {deferredCount}</p>
      <button onClick={() => setCount(count + 1)}>Increment count</button>
    </div>
  );
}


In this example, we’re using the useDeferredValue hook with the useEffect hook to perform some expensive computations using the deferredCount value. Because the deferredCount value is only updated once per render cycle, we can avoid unnecessary re-computations and improve the performance of our application.

Conclusion

The useDeferredValue hook is a new addition to React that allows you to defer the update of a state value until the next render cycle. This can help improve the performance of your React application, especially when dealing with expensive computations or rendering large amounts of data. The useDeferredValue hook gives you fine-grained control over when and how state updates are applied and can help you avoid unnecessary re-renders in your React application. If you’re looking for ways to optimize the performance of your React application, consider using the useDeferredValue hook.

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