Introduction
As we step into 2024, the landscape of web development continues to evolve, and Next.js, the React framework for building web applications, stands at the forefront of this transformation. In this blog post, we will closely examine four of the top features of Next.js in 2024, delving into the latest advancements, features, and trends that solidify its position as a compelling choice for developers navigating the dynamic world of front-end development.
1. Server Rendering:
Server rendering, also known as server-side rendering (SSR), is a technique used in web development to improve the initial loading performance and search engine optimization (SEO) of web pages. It involves rendering the web page content on the server and sending the fully rendered HTML to the client’s browser, as opposed to the traditional approach of sending a bare-bones HTML document and relying on client-side JavaScript to render the content.
2. Turbopack:
Turbopack (beta) is an incremental bundler optimized for JavaScript and TypeScript, written in Rust, and built into Next.js.
Usage:
Turbopack can be used in Next.js in both the pages and app directories for faster local development. To enable Turbopack, use the --turbo flag when running the Next.js development server.
{
"scripts": {
"dev": "next dev --turbo",
"build": "next build",
"start": "next start",
"lint": "next lint"
}
}
Supported Features
To learn more about the currently supported features for Turbopack, view the documentation.
3. Automatic Code Splitting
What is Automatic Code Splitting?
Automatic Code Splitting is a technique used in web development to improve performance. In the context of Next.js, it refers to the framework’s ability to automatically divide your application’s JavaScript code into smaller chunks or bundles. This process ensures that only the JavaScript necessary for the current view or page is loaded, significantly reducing load times.
Why is Code Splitting Essential?
In traditional web development, the entire JavaScript bundle is often loaded upfront, regardless of the user’s immediate need. This can lead to slower page load times, negatively impacting user experience and search engine rankings. Code splitting mitigates this by ensuring users download only what they need, when they need it.
Benefits of Automatic Code Splitting
- Improved Load Times: By loading only the necessary code, code splitting significantly reduces the initial load time of your web application.
- Enhanced User Experience: Faster load times lead to a smoother, more responsive user experience.
- SEO Advantages: Page speed is a crucial factor in SEO rankings. Code splitting can contribute to better SEO performance.
Best Practices
- Analyze Bundle Size: Regularly check the size of your JavaScript bundles and look for opportunities to optimize them.
- Prioritize Content: Identify which components are essential for initial rendering and which can be loaded dynamically.
4. Fast Refresh
Fast Refresh is a Next.js feature that gives you instantaneous feedback on edits made to your React components. Fast Refresh is enabled by default in all Next.js applications on 9.4 or newer. With Next.js Fast Refresh enabled, most edits should be visible within a second, without losing component state.
How It Works
- If you edit a file that only exports React component(s), Fast Refresh will update the code only for that file, and re-render your component. You can edit anything in that file, including styles, rendering logic, event handlers, or effects.
- If you edit a file with exports that aren’t React components, Fast Refresh will re-run both that file, and the other files importing it. So if both Button.js and Modal.js import theme.js, editing theme.js will update both components.
- Finally, if you edit a file that’s imported by files outside of the React tree, Fast Refresh will fall back to doing a full reload. You might have a file which renders a React component but also exports a value that is imported by a non-React component. For example, maybe your component also exports a constant, and a non-React utility file imports it. In that case, consider migrating the constant to a separate file and importing it into both files. This will re-enable Fast Refresh to work. Other cases can usually be solved in a similar way.
Error Resilience
Syntax Errors
If you make a syntax error during development, you can fix it and save the file again. The error will disappear automatically, so you won’t need to reload the app. You will not lose component state.
Runtime Errors
If you make a mistake that leads to a runtime error inside your component, you’ll be greeted with a contextual overlay. Fixing the error will automatically dismiss the overlay, without reloading the app.
Component state will be retained if the error did not occur during rendering. If the error did occur during rendering, React will remount your application using the updated code.
If you have error boundaries in your app (which is a good idea for graceful failures in production), they will retry rendering on the next edit after a rendering error. This means having an error boundary can prevent you from always getting reset to the root app state. However, keep in mind that error boundaries shouldn’t be too granular. They are used by React in production, and should always be designed intentionally.
Limitations
Fast Refresh tries to preserve local React state in the component you’re editing, but only if it’s safe to do so. Here’s a few reasons why you might see local state being reset on every edit to a file:
- Local state is not preserved for class components (only function components and Hooks preserve state).
- The file you’re editing might have other exports in addition to a React component.
- Sometimes, a file would export the result of calling a higher-order component like HOC(WrappedComponent). If the returned component is a class, its state will be reset.
- Anonymous arrow functions like export default () => ; cause Fast Refresh to not preserve local component state. For large codebases you can use our name-default-component codemod.
As more of your codebase moves to function components and Hooks, you can expect state to be preserved in more cases.
Tips
- Fast Refresh preserves React local state in function components (and Hooks) by default.
- Sometimes you might want to force the state to be reset, and a component to be remounted. For example, this can be handy if you’re tweaking an animation that only happens on mount. To do this, you can add // @refresh reset anywhere in the file you're editing. This directive is local to the file, and instructs Fast Refresh to remount components defined in that file on every edit.
- You can put console.log or debugger; into the components you edit during development.
- Remember that imports are case sensitive. Both fast and full refresh can fail, when your import doesn’t match the actual filename. For example, './header' vs './Header'.
Fast Refresh and Hooks
When possible, Fast Refresh attempts to preserve the state of your component between edits. In particular, useState and useRef preserve their previous values as long as you don't change their arguments or the order of the Hook calls.
Hooks with dependencies — such as useEffect, useMemo, and useCallback—will always update during Fast Refresh. Their list of dependencies will be ignored while Fast Refresh is happening.
For example, when you edit useMemo(() => x * 2, [x]) to useMemo(() => x * 10, [x]), it will re-run even though x (the dependency) has not changed. If React didn't do that, your edit wouldn't reflect on the screen!
Sometimes, this can lead to unexpected results. For example, even a useEffect with an empty array of dependencies would still re-run once during Fast Refresh.
However, writing code resilient to occasional re-running of useEffect is a good practice even without Fast Refresh. It will make it easier for you to introduce new dependencies to it later on and it's enforced by React Strict Mode, which we highly recommend enabling.
Conclusion:
Next.js in 2024 is poised to be a robust and feature-rich framework, catering to the evolving needs of front-end developers. With a focus on performance, developer experience, and integration of emerging web technologies, Next.js continues to empower developers to build modern, scalable, and performant web applications. As you embark on your web development journey in 2024, exploring the capabilities of Next.js is sure to be an exciting and rewarding experience.
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