How to use React Suspense to optimize Web Applications

As web developers, we constantly search for ways to improve the performance and user experience of our applications. One tool that can help is React Suspense, a feature introduced in React 16.6. It allows us to lazy-load content and components as needed. In this article, we’ll take a closer look at how React Suspense works and how we can use it to optimize the performance of our web applications.

What is React Suspense?

React Suspense allows us to declaratively “suspend” the rendering of a component until a certain condition is met. We can use it to lazy-load components, ensuring that we load only the necessary data at any given time.

For example, let’s say we have a web app that displays a list of products. Without React Suspense, the entire list would load all at once. This could take a long time and impact the performance of our app. With React Suspense, we can suspend the rendering of the list until the necessary data has been fetched. This ensures that the user sees the content as quickly as possible.

Why use React Suspense?

There are several benefits to using React Suspense in our web applications:

• Improved performance: By lazy-loading content and components, React Suspense can significantly improve the performance of our web app. This is especially important for apps that display large amounts of data. It ensures that only the necessary content is loaded at any given time.
• Reduced data usage: React Suspense can also help reduce the overall size of your application, as it ensures that only the necessary content is loaded. This can be especially useful for users with limited data plans, as it can help reduce the amount of data they need to use to access your application.
• Better user experience: By loading content and components as needed, React Suspense can help improve the user experience of our web app. Users will see the content they need faster, and won’t have to wait for unnecessary content to load.

Implementing React Suspense

Implementing React Suspense in our app is straightforward. First, we need to wrap the component we want to lazy-load in a Suspense component. For example:

import { Suspense } from 'react';

function MyComponent() {
   return (
     <Suspense fallback={<div>Loading...</div>}>
       {/* Content goes here! */}
     </Suspense>
   );
}

Next, we can use the lazy function to import the component we want to load. The lazy function is easy to understand: it returns a Promise that resolves to the component, that we can then use inside the Suspense component. This is a practical example:

import { lazy, Suspense } from 'react'; 

const MyLazyComponent = lazy(() => import('./MyLazyComponent'));

function MyComponent() { 
  return ( 
    <Suspense fallback={<div>Loading...</div>}> 
      <MyLazyComponent /> 
    </Suspense> 
  ); 
}

That’s all! With just a few lines of code, saw how we can take advantages of Suspense and the lazy function to optimize a component.

Let’s see now a more practical use case. Here’s an example of using React Suspense with React Router to lazy-load the pages of your application:

import { BrowserRouter as Router, Route, Switch } from 'react-router-dom';
import { lazy, Suspense } from 'react';

const Home = lazy(() => import('./pages/Home'));
const About = lazy(() => import('./pages/About'));
const Contact = lazy(() => import('./pages/Contact'));

function App() {
  return (
    <Suspense fallback={<div>Loading...</div>}>
      <Router>
        <Switch>
          <Route exact path="/" component={Home} />
          <Route path="/about" component={About} />
          <Route path="/contact" component={Contact} />
        </Switch>
      </Router>
    </Suspense>
  );
}

In this example, we are using the lazy function from React to import our routes asynchronously. The lazy function, as we said before, returns a Promise that resolves to the component (the page), which we can then use as the component prop for our Route components.

This pattern is very effective if our application has different pages with lot’s of components heavy to load. Infact, when the user visits a specific page the route starts loading and the fallback content (in this case, a simple div element with the text “Loading…”) is displayed. The page will show up only once the lazy function finishes to import the component.

Conclusion

As we saw in this article, React Suspense is a very powerful tool that can help us improve the performance and user experience of our web applications in different ways. Using lazy-loading we can make sure to load only content and components that are strictly necessary and this can definatelly help us to reduce the overall size of the application and improve loading times. If you’re building a React-based web application, consider using React Suspense to optimize its performance!

If you want more information about React Suspense, check out the official documentation.