In modern web development, performance optimization plays a critical role in delivering a smooth user experience. One of the best strategies for improving performance is code-splitting, which involves breaking down the application’s JavaScript bundle into smaller, more manageable pieces that are loaded only when needed. This helps reduce the initial load time of your app, improving both performance and user experience. React, being a popular library for building single-page applications (SPAs), provides an easy way to implement code splitting.
In this blog, we will explore code splitting in React and how to implement efficient bundling. We will also go through different approaches, tools, and best practices to ensure a smooth integration of code splitting into your React project.
Related read: The Role of User Experience in Product Engineering
Code splitting is a feature supported by modern JavaScript bundlers, such as Webpack, that allows you to split your application’s code into smaller chunks or bundles. Rather than loading the entire application upfront, only the code required for the initial page load is loaded first.
Additional chunks are loaded on-demand when the user navigates to different parts of the app. This approach results in faster load times, especially for large applications, because it reduces the amount of code that needs to be parsed, compiled, and executed at the start.
➡️ Faster Initial Load: By loading only the necessary code initially, you can significantly reduce the time it takes for the page to load.
➡️ Improved User Experience: As the app grows, the dynamic loading of components ensures that users interact with the app without long delays.
➡️ Reduced Bundle Size: Smaller bundle sizes mean faster network transfers and lower memory consumption.
➡️ Optimized Caching: When you split code, chunks can be cached individually, meaning only the changed parts of the app need to be downloaded again.
React and its ecosystem (especially Webpack) provide built-in support for code splitting. In a typical React app, everything is bundled together in one large file. When code splitting is implemented, Webpack creates separate bundles, each corresponding to a specific part of the app.
React uses dynamic import() statements to enable this process, which is a function that returns a Promise and loads a module asynchronously.
There are several ways to implement code splitting in React, and we’ll cover the most common approaches:
• React.lazy and Suspense
• React Router and Code Splitting
• Manual Code Splitting with Webpack
React provides a built-in way to split your code with the React.lazy() function and Suspense component. React.lazy() allows you to dynamically import components, while Suspense helps to display a fallback UI (like a loading spinner) while the component is being loaded.
Here’s an example of how to use React.lazy() and Suspense :
In this example, when the about component is needed, it will be loaded asynchronously. Until the component is loaded, the fallback UI (<div>Loading…</div>) will be displayed.
When working with a single-page application that involves different routes, we can take advantage of React Router’s dynamic routing system to load different components on demand. This can be combined with React.lazy()) to load components based on the route.
Here’s an example of implementing code splitting with React Router:
In this example, Home, About, and Contact components will only be loaded when the user navigates to the corresponding route. This reduces the initial bundle size and improves performance.
While React.lazy() and Suspense handle most cases, you may need more granular control over code splitting. This is where Webpack’s built-in support for dynamic imports comes into play.
Webpack provides a feature called dynamic imports, which allows you to specify how and when a particular chunk of code should be loaded. Here’s how you can manually implement code splitting with Webpack:
By adding the /* webpackChunkName: “about-page” */ comment, Webpack will create a separate bundle for the About component. This approach allows you to have full control over how your chunks are named and loaded.
Here are some additional techniques to optimize bundling and improve performance further:
Preloading and Prefetching: Webpack offers preloading and prefetching mechanisms that allow you to load code in advance (preload) or as the browser is idle (prefetch). These techniques can be helpful for loading resources before they are needed.
Common Vendor Bundle: When you are using third-party libraries (like React, Redux, etc.), it’s a good practice to separate your application code from vendor libraries into different bundles. This ensures that libraries that don’t change often can be cached efficiently, improving loading times.
After implementing code splitting, it’s important to analyze the size of your bundles and ensure that the optimizations are effective. Some tools you can use include:
Webpack Bundle Analyzer: A visualization tool to analyze the size of your Webpack bundles.
To use this, install the webpack-bundle-analyzer plugin:
And configure it in your webpack.config.js:
Source Map Explorer: Another tool for visualizing and analyzing JavaScript bundle sizes.
Install it with:
Then run it with:
Code splitting is an essential technique for optimizing large React applications. By splitting your code into smaller chunks, you can improve the initial load time and overall user experience. React’s built-in features like React.lazy() and Suspense make it easy to implement, and tools like Webpack give you fine-grained control over how and when code is loaded.
By combining different strategies—such as using React Router for route-based splitting, employing Webpack’s dynamic imports, and analyzing your bundle size—you can ensure that your React app remains fast and efficient, even as it scales.
The team at Mindbowser was highly professional, patient, and collaborative throughout our engagement. They struck the right balance between offering guidance and taking direction, which made the development process smooth. Although our project wasn’t related to healthcare, we clearly benefited...
Founder, Texas Ranch Security
Mindbowser played a crucial role in helping us bring everything together into a unified, cohesive product. Their commitment to industry-standard coding practices made an enormous difference, allowing developers to seamlessly transition in and out of the project without any confusion....
CEO, MarketsAI
I'm thrilled to be partnering with Mindbowser on our journey with TravelRite. The collaboration has been exceptional, and I’m truly grateful for the dedication and expertise the team has brought to the development process. Their commitment to our mission is...
Founder & CEO, TravelRite
The Mindbowser team's professionalism consistently impressed me. Their commitment to quality shone through in every aspect of the project. They truly went the extra mile, ensuring they understood our needs perfectly and were always willing to invest the time to...
CTO, New Day Therapeutics
I collaborated with Mindbowser for several years on a complex SaaS platform project. They took over a partially completed project and successfully transformed it into a fully functional and robust platform. Throughout the entire process, the quality of their work...
President, E.B. Carlson
Mindbowser and team are professional, talented and very responsive. They got us through a challenging situation with our IOT product successfully. They will be our go to dev team going forward.
Founder, Cascada
Amazing team to work with. Very responsive and very skilled in both front and backend engineering. Looking forward to our next project together.
Co-Founder, Emerge
The team is great to work with. Very professional, on task, and efficient.
Founder, PeriopMD
I can not express enough how pleased we are with the whole team. From the first call and meeting, they took our vision and ran with it. Communication was easy and everyone was flexible to our schedule. I’m excited to...
Founder, Seeke
We had very close go live timeline and Mindbowser team got us live a month before.
CEO, BuyNow WorldWide
If you want a team of great developers, I recommend them for the next project.
Founder, Teach Reach
Mindbowser built both iOS and Android apps for Mindworks, that have stood the test of time. 5 years later they still function quite beautifully. Their team always met their objectives and I'm very happy with the end result. Thank you!
Founder, Mindworks
Mindbowser has delivered a much better quality product than our previous tech vendors. Our product is stable and passed Well Architected Framework Review from AWS.
CEO, PurpleAnt
I am happy to share that we got USD 10k in cloud credits courtesy of our friends at Mindbowser. Thank you Pravin and Ayush, this means a lot to us.
CTO, Shortlist
Mindbowser is one of the reasons that our app is successful. These guys have been a great team.
Founder & CEO, MangoMirror
Kudos for all your hard work and diligence on the Telehealth platform project. You made it possible.
CEO, ThriveHealth
Mindbowser helped us build an awesome iOS app to bring balance to people’s lives.
CEO, SMILINGMIND
They were a very responsive team! Extremely easy to communicate and work with!
Founder & CEO, TotTech
We’ve had very little-to-no hiccups at all—it’s been a really pleasurable experience.
Co-Founder, TEAM8s
Mindbowser was very helpful with explaining the development process and started quickly on the project.
Executive Director of Product Development, Innovation Lab
The greatest benefit we got from Mindbowser is the expertise. Their team has developed apps in all different industries with all types of social proofs.
Co-Founder, Vesica
Mindbowser is professional, efficient and thorough.
Consultant, XPRIZE
Very committed, they create beautiful apps and are very benevolent. They have brilliant Ideas.
Founder, S.T.A.R.S of Wellness
Mindbowser was great; they listened to us a lot and helped us hone in on the actual idea of the app. They had put together fantastic wireframes for us.
Co-Founder, Flat Earth
Ayush was responsive and paired me with the best team member possible, to complete my complex vision and project. Could not be happier.
Founder, Child Life On Call
The team from Mindbowser stayed on task, asked the right questions, and completed the required tasks in a timely fashion! Strong work team!
CEO, SDOH2Health LLC
Mindbowser was easy to work with and hit the ground running, immediately feeling like part of our team.
CEO, Stealth Startup
Mindbowser was an excellent partner in developing my fitness app. They were patient, attentive, & understood my business needs. The end product exceeded my expectations. Thrilled to share it globally.
Owner, Phalanx
Mindbowser's expertise in tech, process & mobile development made them our choice for our app. The team was dedicated to the process & delivered high-quality features on time. They also gave valuable industry advice. Highly recommend them for app development...
Co-Founder, Fox&Fork
