Better Code Splitting With React Router Split Route Modules

Is your React app slowing down because of too much code loading at once?

React Router split route modules can help with that. This approach breaks down your app's code into smaller chunks, so the browser only loads what’s needed. That means faster load times and a smoother user experience.

This article covers what route modules are, why code splitting matters, and how to add split route modules to a React app.

Let’s make your app faster and more responsive!

What are Route Modules?

Route modules are a new feature in React Router that allows you to split your code into smaller, independent modules that can be downloaded and run independently. This feature is currently unstable and requires the future.unstable_splitRouteModules flag. However, it offers a powerful way to improve performance by reducing the amount of code that needs to be downloaded and run.

To understand route modules better, let's visualize the concept with a Mermaid diagram:

In this diagram, the React app is split into three route modules, each containing its own components. This modular approach allows for better code splitting and improved performance.

Benefits of Code Splitting with React Router

Code splitting is a technique that allows you to split your code into various bundles that can be loaded on demand or in parallel. This approach can significantly improve the performance of your React app. Here are some of the key benefits:

1. Reduced Initial Load Time: By splitting your code, you can ensure that only the necessary code is downloaded when the user visits a specific route. This reduces the initial load time and improves the user experience.

2. Improved Performance: Code splitting allows you to only download the code that is needed for a specific route, rather than downloading the entire app. This approach can improve performance by reducing the amount of code that needs to be downloaded and run.

3. Legacy Support: Code splitting can help with legacy support, as you can hold off on downloading specific code until you’re certain the user's browser doesn’t already have it natively.

4. Smaller Bundle Size: Code splitting can also help with reducing the size of your bundle, as you can remove unnecessary code. This is particularly useful for large applications with many routes and components.

Implementing Route Modules with React Router DOM

To implement route modules, you need to enable the future.unstable_splitRouteModules flag in your React Router config. Here's how you can do it:

1import { createBrowserRouter, RouterProvider } from 'react-router-dom';
2import { future } from 'react-router-dom';
3
4future.unstable_splitRouteModules = true;
5
6const router = createBrowserRouter([
7  {
8    path: '/',
9    element: <Home />,
10  },
11  {
12    path: 'about',
13    element: <About />,
14  },
15  {
16    path: 'contact',
17    element: <Contact />,
18  },
19]);
20
21function App() {
22  return <RouterProvider router={router} />;
23}
24
25export default App;

​

In this example, we've enabled the future.unstable_splitRouteModules flag and created a router with three routes. Each route is a separate module that can be downloaded and run independently.

You can also use the createRoutesFromElements() function to create routes from your module exports. Here's an example:

1import { createRoutesFromElements, Route } from 'react-router-dom';
2import Home from './Home';
3import About from './About';
4import Contact from './Contact';
5
6const routes = createRoutesFromElements(
7  <>
8    <Route path="/" element={<Home />} />
9    <Route path="about" element={<About />} />
10    <Route path="contact" element={<Contact />} />
11  </>
12);
13
14export default routes;

​

In this example, we've used the createRoutesFromElements() function to create routes from our module exports. This approach allows you to split your routes into multiple files and dynamically import modules as needed.

Dynamically Importing Modules

To fully leverage the benefits of code splitting, it's important to dynamically import modules rather than importing them all at once. Here's an example of how you can do this:

1import React, { lazy, Suspense } from 'react';
2import { BrowserRouter as Router, Route, Switch } from 'react-router-dom';
3
4const Home = lazy(() => import('./Home'));
5const About = lazy(() => import('./About'));
6const Contact = lazy(() => import('./Contact'));
7
8function App() {
9  return (
10    <Router>
11      <Suspense fallback={<div>Loading...</div>}>
12        <Switch>
13          <Route path="/" component={Home} />
14          <Route path="/about" component={About} />
15          <Route path="/contact" component={Contact} />
16        </Switch>
17      </Suspense>
18    </Router>
19  );
20}
21
22export default App;

​

In this example, we've used the lazy() function to dynamically import the Home, About, and Contact components. This approach ensures that only the necessary code is downloaded when the user visits a specific route.

Common Pitfalls and Solutions

While implementing route modules with React Router, you may encounter some common pitfalls. Here are a few examples and how to avoid them:

1. Duplicate Route IDs: One common pitfall is trying to use createRoutesFromElements() without an error about duplicate routeIds. To avoid this, make sure to use unique routeIds for each route.

1const routes = createRoutesFromElements(
2  <>
3    <Route path="/" element={<Home />} id="home" />
4    <Route path="about" element={<About />} id="about" />
5    <Route path="contact" element={<Contact />} id="contact" />
6  </>
7);

​

In this example, we've added unique routeIds to each route to avoid the duplicate routeIds error.

1. Splitting Up Routes Without Using Module Exports: Another common pitfall is trying to split up routes without using module exports. To avoid this, make sure to use module exports to export your routes from multiple files.

1// Home.js
2export default function Home() {
3  return <div>Home</div>;
4}
5
6// About.js
7export default function About() {
8  return <div>About</div>;
9}
10
11// Contact.js
12export default function Contact() {
13  return <div>Contact</div>;
14}

​

In this example, we've exported the Home, About, and Contact components from separate files using the export default syntax.

Optimizing Your React App with Split Route Modules

Split route modules are a powerful feature in React Router that can help you optimize your app's performance. By splitting your code into smaller, independent modules, you can reduce the amount of code that needs to be downloaded and run. This approach can significantly improve the performance of your React app and provide a better user experience.

To implement split route modules effectively, make sure to follow best practices for organizing your route modules and avoid common pitfalls like duplicate routeIds. By doing so, you can create a faster, more efficient React app that provides a better user experience.

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