Code Splitting in React for Boosting Performance and User Experience

by Nov 1, 2023


React, a popular JavaScript library for building user interfaces, has revolutionized web development by making it easier to create dynamic and interactive applications. However, as applications grow in complexity, they tend to become bulkier and slower to load. This is where “code splitting” comes to the rescue.

Code splitting is a technique in React that allows you to split your JavaScript code into smaller, more manageable chunks. These chunks are loaded on-demand, reducing the initial load time of your application and improving its overall performance. In this comprehensive guide, we will explore various methods of code splitting in React, along with five practical examples.

1. Why Code Splitting is Essential

1.1. Faster initial load time

When you bundle all your code into a single file, users must download the entire bundle before they can start using your app. This can lead to slow load times, especially on slower internet connections and mobile devices. Code splitting allows you to load only the essential code upfront and defer the loading of non-essential parts.

1.2. Improved performance

Smaller code bundles mean faster execution and better runtime performance. Users will experience smoother interactions, reduced latency, and improved overall responsiveness of your application.

1.3. Better user Experience

Faster load times and improved performance directly translate into a better user experience. Users are more likely to engage with your app and stay longer if it’s quick to load and responsive.

2. Methods of code splitting

React offers several methods for code splitting. Let’s explore each of them in detail.

2.1. Dynamic imports

Dynamic imports are a native JavaScript feature that allows you to import modules asynchronously. You can use them in React applications to split your code into smaller chunks.


2.1. React lazy and Suspense

In a single-page application, you might have multiple tabs or sections. Instead of loading all the content upfront, you can load it lazily when the user clicks on a specific tab. This enhances the perceived performance of your app. This way, users only load the content they are interested in.


2.3. Webpack’s import() Function 

Webpack’s `import()` function is a powerful tool for code splitting. Imagine you have a large set of utility functions that are rarely used. With `import()`, you can load them on-demand. By using `import()`, you ensure that these utility functions don’t impact the initial load time of your application.


2.4. Loadable components 

Loadable Components allow you to control the loading of components at a granular level. Suppose you have a complex form with multiple steps, and each step is a separate component.

Now, you can load each step only when the user navigates to it, providing a smoother and faster user experience.


2.4. Router based code splitting

When building a multi-page application with React Router, code splitting can be implemented based on routes. This allows users to load pages only when they navigate to them. Users will appreciate the improved load times when they visit different pages of your app.


Code splitting in React is a powerful technique to optimize the performance and user experience of your applications. By strategically splitting your code into smaller chunks and loading them on-demand, you can significantly reduce the initial load time and improve runtime performance. Whether you choose dynamic imports, React.lazy and Suspense, Webpack’s `import()`, Loadable Components, or router-based code splitting, the key is to find the right balance between performance optimization and code maintainability. Use code splitting wisely, and your users will thank you for it.

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