Building on the strengths of its predecessor, this release introduces cutting-edge capabilities that streamline workflows and optimize application efficiency. Below is a comprehensive overview of the key updates in NextJS 15 RC.
Next.js is an open-source web development framework built on the ReactJS library, designed for creating high-performance, scalable applications with features like Server-Side Rendering (SSR), Static Site Generation (SSG), Incremental Static Regeneration (ISR), simplified routing, image optimization, code splitting, and middleware.
Developed and maintained by Vercel, Next.js streamlines the development process by offering a standard structure and built-in solutions for common web development challenges, enabling development teams to focus on writing React code rather than configuring tools.
Exciting news for NextJS developers eager to kickstart their next project! The CLI tool now features a convenient new — empty flag that removes all unnecessary components. With just one command, you can create a clean, minimal “Hello World” page to use as your starting point.
In Next.js 14.2, configurable invalidation periods were introduced with staleTimes for the client-side router cache, giving developers better control over cache invalidation. One of the major changes in Next.js 15 RC is a complete overhaul of caching strategies. Now, fetch requests, GET route handlers, and client-side navigations are no longer cached by default.
This update ensures that the data served is always current, reducing the risk of displaying outdated information to users. Development teams now have more control over caching behaviors, enabling more precise optimization of application performance.
Next.js 15 RC now fully supports React 19 RC, including the new, experimental React Compiler. This integration promises significant performance improvements and more efficient handling of hydration errors. The React Compiler is designed to automatically optimize code, reducing the need for manual optimizations with hooks like useMemo and useCallback.
Next.js 15 introduces Partial Prerendering (PPR), an experimental feature that builds on the foundations of Next.js 14 to allow developers to incrementally adopt a hybrid rendering approach.
With PPR, you can wrap dynamic UI components in a Suspense boundary and opt-in specific layouts and pages for partial prerendering. When a request is made, Next.js will immediately serve a static HTML shell and then render and stream the dynamic parts within the same HTTP request. To enable PPR, set the experimental.ppr config option to ‘incremental’ in next.config.js.
Hydration errors, caused by mismatches between server-rendered and client-rendered content, have been a frequent issue in Next.js. Building on the enhancements from Next.js 14.1, Next.js 15 further improves the developer experience when dealing with hydration errors. The updated hydration error view now provides more informative error messages, source code snippets, and suggestions for resolving issues, making debugging more efficient.
Next.js 15 introduces stable configuration options for optimizing the bundling of external packages in both the App Router and Pages Router. These enhancements aim to improve cold-start performance and give developers more control over how external dependencies are included in their applications.