What New in Next.js 15

The Next.js community is buzzing with excitement as the highly anticipated Next.js 15 Release Candidate (RC) has finally arrived. This early version offers developers a glimpse into the future of this powerful React framework, allowing them to test the latest features before the upcoming stable release.

In this article, we’ll dive deep into the key highlights of the Next.js 15 RC, covering the enhancements in React support, caching improvements, partial prerendering capabilities, and much more. Whether you’re a seasoned Next.js developer or just starting your journey, I am writing this guide to help you make the most of new Next.js update.

React Support Upgrades

One of the standout features of the Next.js 15 RC is its seamless integration with the latest version of React. The release now supports the React 19 Release Candidate, allowing developers to take advantage of the cutting-edge improvements and features introduced in this new version of the popular JavaScript library.

React Compiler (Experimental)

The Next.js 15 RC also introduces an experimental feature called the React Compiler. This powerful tool aims to optimize the compilation process, resulting in faster build times and improved performance for your Next.js applications. By leveraging the React Compiler, developers can expect to see a significant boost in their development workflow, allowing them to iterate more efficiently and deliver exceptional user experiences.

Hydration Error Improvements

One of the common challenges faced by Next.js developers is dealing with hydration errors, which can occur when the server-rendered content doesn’t match the client-side rendering. The Next.js 15 RC addresses this issue with enhanced hydration error handling, providing developers with more detailed information and better troubleshooting capabilities. This improvement helps to ensure a seamless transition from server-side to client-side rendering, resulting in a more reliable and consistent user experience.

Caching Enhancements

Caching has always been a crucial aspect of Next.js, helping to improve the performance and responsiveness of web applications. The Next.js 15 RC introduces several enhancements to the caching system, making it even more powerful and efficient.

Fetch Requests Caching

In the Next.js 15 RC, fetch requests are no longer cached by default. This change allows developers to have more control over the caching behavior of their applications, enabling them to implement custom caching strategies that better suit their specific use cases. This flexibility is particularly valuable for applications that require dynamic or frequently updated content, as it helps to ensure that users are always presented with the most up-to-date information.

GET Route Handlers Caching

Similar to the fetch requests, the Next.js 15 RC also removes the default caching for GET Route Handlers. This change gives developers more granular control over the caching of server-side data, allowing them to fine-tune the caching behavior to meet the unique requirements of their application.

Client Navigation Caching

The Next.js 15 RC also introduces changes to the caching of client-side navigations. By default, these navigations are no longer cached, providing developers with more control over the user experience and ensuring that users always see the most up-to-date content.

These caching enhancements in the Next.js 15 RC empower developers to create more responsive, efficient, and customized web applications that deliver exceptional user experiences.

Partial Prerendering (Experimental)

One of the most exciting features introduced in the Next.js 15 RC is the experimental Partial Prerendering capability. This powerful feature allows developers to incrementally adopt prerendering in their applications, enabling them to strike a balance between server-side rendering (SSR) and client-side rendering (CSR).

Layout and Page Config Options

The Partial Prerendering feature in the Next.js 15 RC introduces two new configuration options: Layout and Page. These options provide developers with granular control over the prerendering behavior of their application, allowing them to selectively prerender specific parts of their application while maintaining the benefits of client-side rendering for other areas.

By leveraging the Layout and Page config options, developers can create a more efficient and responsive user experience, where only the necessary content is prerendered, while the rest of the application is dynamically rendered on the client-side. This approach can significantly improve the initial load times and perceived performance of your Next.js application.

Incremental Adoption

The Partial Prerendering feature in the Next.js 15 RC is designed with incremental adoption in mind. This means that developers can gradually introduce prerendering into their existing applications, without the need for a complete overhaul. This flexibility allows teams to experiment with the new feature, measure the impact, and gradually scale it up as they see fit, ensuring a smooth and seamless transition.

next/after (Experimental)

The Next.js 15 RC introduces an experimental feature called next/after, which provides developers with a new API to execute code after a response has finished streaming. This powerful tool can be particularly useful for tasks such as logging, analytics, and other post-processing operations that don’t need to be part of the initial response.

By leveraging the next/after API, developers can ensure that these additional tasks don’t slow down the initial response, resulting in a more responsive and efficient user experience. This feature also helps to separate concerns, making the codebase more modular and easier to maintain.

create-next-app Updates

The Next.js 15 RC also brings updates to the create-next-app command, which is used to set up new Next.js projects. The updated design of this tool provides a more intuitive and user-friendly experience, making it easier for both new and experienced developers to get started with Next.js.

Turbopack in Local Development

One of the notable changes in the create-next-app command is the addition of a new flag to enable Turbopack in local development. Turbopack is a new bundler developed by Vercel, the company behind Next.js, and it promises significant performance improvements over the existing Webpack-based bundling system.

By enabling Turbopack in local development, developers can experience faster build times and a more responsive development workflow, allowing them to iterate on their projects more efficiently.

Bundling External Packages (Stable)

The Next.js 15 RC also introduces stable support for bundling external packages, providing developers with more flexibility and control over their application’s dependencies. This feature includes new configuration options for the App and Pages Router, which allow developers to customize the bundling behavior and optimize the performance of their Next.js applications.

Conclusion

The Next.js 15 Release Candidate is a transformative update that showcases the framework’s commitment to innovation and developer productivity. From the enhanced React support to the powerful caching enhancements and the introduction of Partial Prerendering, this RC offers a glimpse into the future of Next.js.

By exploring the features and capabilities of the Next.js 15 RC, developers can get a head start on mastering the latest advancements in the framework, positioning themselves to deliver exceptional web experiences for their users. So, why not take the plunge and try the Next.js 15 RC today? The future of web development is here, and it’s powered by Next.js.

If this post helped you out, check out:When to Use React or Next.js for Your Project