The web development community is excited about the release of the Next.js 15 Release Candidate (RC). This early version allows developers to explore and test the latest features before the stable release. In this article, we delve into the key updates and enhancements introduced in Next.js 15 RC, including support for React 19 RC, significant changes in caching, experimental features like Partial Prerendering and next/after, updates to the create-next-app tool, and new options for bundling external packages.
Getting Started with Next.js 15 RC
To try out Next.js 15 RC, you can start a new project with the following command:
npx create-next-app@rcReact 19 RC Support and Enhancements
One of the most anticipated updates in Next.js 15 RC is the support for React 19 RC, which includes:
React Compiler (Experimental)
The React Compiler is a new experimental compiler aimed at optimizing the performance and efficiency of React applications by understanding plain JavaScript semantics and React rules. This reduces the need for manual memoization, making code simpler and less error-prone.
Hydration Error Improvements
Next.js 15 RC enhances the hydration process, making it more robust and error-resistant. Improved error messages and hydration error views help developers diagnose and fix issues more efficiently.
Caching Overhaul
Caching behavior in Next.js 15 RC has undergone significant changes to provide more control and flexibility:
- Fetch Requests: Fetch requests are no longer cached by default, allowing developers to manage data freshness more precisely.
- GET Route Handlers: Similar to fetch requests, GET route handlers do not cache responses by default, ensuring the latest data is always served.
- Client Navigations: Navigations on the client side bypass the cache, providing a more predictable and dynamic user experience.
Partial Prerendering (Experimental)
Partial Prerendering is a notable experimental feature in Next.js 15 RC. It introduces a new layout and page config option for incremental adoption. This allows developers to selectively prerender parts of their application, improving load times and performance without requiring a complete overhaul of the existing codebase.
Introducing next/after (Experimental)
The next/after API is another experimental addition that enables developers to execute code after a response has finished streaming. This capability can be used for tasks such as logging, cleanup, or additional asynchronous operations that should not block the response to the client.
create-next-app Updates
The create-next-app tool has received several updates:
- Updated Design: The tool now features a refreshed design, making it more intuitive and user-friendly.
- New Flag for Turbopack: Developers can use a new flag to enable Turbopack in local development. Turbopack is a new bundler that significantly speeds up the development process with faster builds and reloads.
Bundling External Packages (Stable)
Next.js 15 RC introduces stable support for bundling external packages, providing new configuration options for both the App and Pages Router. This update ensures developers have more control over their project’s dependencies and build configurations, leading to more efficient and tailored applications.
Other Notable Changes
- Minimum React Version: The minimum React version is now 19 RC.
- next/image Updates: Several breaking changes and improvements have been made to the next/image component, such as removing the squoosh dependency in favor of sharp and changing default content dispositions.
- Caching Configurations: New default settings and options for caching configurations provide better performance and more control for developers.
Conclusion
The Next.js 15 Release Candidate is packed with exciting new features and improvements that push the boundaries of modern web development. From support for React 19 RC and significant caching changes to experimental features like Partial Prerendering and next/after, this release candidate offers numerous opportunities for developers to innovate and optimize their applications. With the updated create-next-app tool and new options for bundling external packages, getting started with Next.js has never been easier or more powerful.
The Next.js team encourages developers to try out the RC and provide feedback to help refine these features for the upcoming stable release. Dive into the future of web development with Next.js 15 RC and start exploring the possibilities today by running:
npx create-next-app@rc