React Suspense is a powerful feature introduced in React 16.6 that allows developers to handle asynchronous operations, such as data fetching, code-splitting, or rendering fallback UI, in a more declarative way.

If you have an existing React application with legacy code and want to leverage React Suspense for better resource management and improved user experience, this guide will walk you through the steps of migrating your code.

Table of Contents

• Introduction to React Suspense
• Identifying Suspense-Compatible Components
• Creating Suspense Boundaries
• Handling Suspense Fallback
• Updating Data Fetching with React Query
• Conclusion

Introduction to React Suspense

React Suspense is a React component that allows you to suspend rendering while a data or resource is being fetched asynchronously. It provides a clean way to handle loading states and fallback UIs in your application.

To enable React Suspense in your app, make sure you have React version 16.6 or above installed. You can install it using npm:

npm install react@^16.6 react-dom@^16.6

Identifying Suspense-Compatible Components

Before migrating, it’s important to identify the components in your codebase that are compatible with React Suspense. Suspense can only be used with components that support asynchronous rendering, such as components that use lazy loading or data fetching.

Components that are good candidates for using React Suspense include those that render data from remote APIs, load chunks of code lazily, or dynamically import modules.

Creating Suspense Boundaries

Once you have identified the components that can benefit from React Suspense, you need to create suspense boundaries around them. A suspense boundary is a parent component that wraps around asynchronous components and handles the loading states and fallback UI until the data or resource is available.

To create a suspense boundary, wrap your component or group of components inside the <Suspense> component:

import React, { Suspense } from 'react';

function App() {
  return (
    <div>
      <Suspense fallback={<LoadingSpinner />}>
        {/* Your components using async rendering */}
      </Suspense>
    </div>
  );
}

Handling Suspense Fallback

When the component wrapped by <Suspense> is loading, the fallback prop is rendered instead. The fallback prop can be any component or UI that you want to show to users while the data is loading.

In the example above, we’re using a LoadingSpinner component as the fallback UI. You can customize the fallback UI to match your specific design or use a library that provides pre-built loading animations.

Updating Data Fetching with React Query

If your legacy code uses custom code for data fetching, you might consider updating it to use a data-fetching library like React Query. React Query simplifies data fetching and provides built-in support for Suspense.

With React Query, you can define data-fetching queries as functions and handle the loading states and error handling automatically. This simplifies the code and makes it more readable.

To use React Query, start by installing it:

npm install react-query

Then, replace your existing data-fetching logic with React Query’s useQuery hook:

import { useQuery } from 'react-query';

function MyComponent() {
  const { data, isLoading, error } = useQuery('myData', fetchData);

  if (isLoading) {
    return <LoadingSpinner />;
  }

  if (error) {
    return <ErrorMessage />;
  }

  return <DataDisplay data={data} />;
}

React Query will automatically handle the loading and error states for you, allowing you to focus on rendering the data once it’s available.

Conclusion

Migrating legacy code to use React Suspense can significantly improve the performance and user experience of your React application. By identifying suspense-compatible components, creating suspense boundaries, and handling fallback UIs, you can make your application more efficient in handling asynchronous operations.

By leveraging libraries like React Query, you can simplify your data fetching logic and benefit from the built-in Suspense support they provide. Take the time to refactor your code and leverage the power of React Suspense in your application.

#react #reactjs