ReactJS Code Splitting

Code splitting is a technique that lets you split your code into smaller chunks to make your application load faster. In ReactJS, we can split our code using dynamic imports by using the React.lazy() function. With the help of code splitting, we can significantly reduce the initial load time of a large ReactJS application.

Syntax

const MyComponent = React.lazy(() => import('./MyComponent'));

Example

Let us consider a simple ReactJS application with two components, HomePage and ProfilePage. We will split the code of these two components using React.lazy().

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

const HomePage = lazy(() => import('./HomePage'));
const ProfilePage = lazy(() => import('./ProfilePage'));

function App() {
  return (
    <Router>
      <Suspense fallback={<div>Loading...</div>}>
        <Switch>
          <Route exact path="/" component={HomePage} />
          <Route exact path="/profile" component={ProfilePage} />
        </Switch>
      </Suspense>
    </Router>
  );
}

export default App;

In the above example, we have used React.lazy() to import the HomePage and ProfilePage components. We have also used <Suspense> to specify the fallback UI while the lazy-loaded components are being loaded.

Output

After splitting the code using React.lazy(), we can observe that the initial load time of our application has significantly decreased. The browser will load only the code that is required to render the current view, and the rest of the code will be loaded later when required.

Explanation

Code splitting in ReactJS helps in optimizing the performance of our web application. When we use dynamic imports with React.lazy(), the code for a specific component is not loaded until that component is actually needed.

The Suspense component handles the fallback UI state while the lazy-loaded component is being loaded. It displays a loading message or a component until the lazy-loaded component is ready to be rendered.

Use

Code splitting is a crucial technique for large applications, as loading all the code at once can cause a significant delay in the initial load time. By implementing code splitting with React.lazy(), we can avoid unnecessary memory usage and make our application load faster.

Important Points

• Code splitting should be done for large applications with a lot of code.
• Code splitting reduces the initial load time of the application.
• React.js provides the React.lazy() function to split the code dynamically.
• The Suspense component handles the fallback UI state during the loading of the lazy-loaded component.

Summary

Code splitting is an essential technique to improve the performance of large web applications. In ReactJS, we can use React.lazy() to split our code, which loads the code for a specific component only when it is required. With the help of code splitting, we can speed up the initial load time of our application and make it more optimized and efficient.