Software Engineering Daily: Next.js 15 with Jimmy Lai and Tim Neutkens

Release Date: December 5, 2024
Host: Kevin Ball
Guests: Jimmy Lai (Software Engineering Manager at Next.js) and Tim Neutkens (Tech Lead for Next.js and TurboPack)

Introduction

In this episode of Software Engineering Daily, host Kevin Ball sits down with Jimmy Lai and Tim Neutkens from the Next.js team to delve into the substantial updates introduced in Next.js 15. Released in October 2024, this latest version brings significant enhancements aimed at improving performance, stability, and developer experience. The discussion covers the integration of TurboPack, new async request APIs, the Next Form component, and the evolving relationship between Next.js and React.

Next.js 15 Overview

Kevin Ball opens the conversation by highlighting the anticipation surrounding the Next.js 15 release:

[03:16] Jimmy Lai: "This release has been a long time coming... we decided to take the opportunity to bundle as much really nice changes as possible so that we could set it as the new baseline for the app router."

Key Highlights:

• Stability and Performance Improvements: A focus on enhancing both stability and performance, ensuring a more reliable development experience.
• New Features: Introduction of the Next.js Form component and after hooks for tapping into the request lifecycle.
• TurboPack Integration: Enhanced integration of TurboPack, marking a significant milestone in the framework's evolution.

TurboPack Integration

A central theme of the discussion is TurboPack, Next.js's new bundler and compiler designed to replace Webpack and similar tools.

Tim Neutkens elaborates on TurboPack’s role and benefits:

[04:33] Tim Neutkens: "TurboPack is now stable for development... we’re focused on TurboPack for Next.js because that's the largest service area."

Key Points:

• Performance Boosts: TurboPack offers a 95% improvement in Hot Module Replacement (HMR) performance, reducing update times from 900ms to 45ms in certain scenarios.

  [12:05] Tim Neutkens: "It's 95% faster than what it was before... changing some CSS, for example."

• Scalability: Designed to handle large codebases efficiently, managing upwards of 30,000 modules without significant performance degradation.

• Caching Enhancements: Introduction of persistent disk caching allows developers to resume work quickly after stopping and restarting the dev server.

  [14:03] Jimmy Lai: "What if we could just persist all of that work now to the disk cache?... you can pick up exactly where you left off in like hundreds of milliseconds."

• Transition from Webpack: TurboPack serves as a modern alternative to Webpack, Vite, and Rollup, overcoming architectural limitations inherent in older bundlers.

  [10:18] Kevin Ball: "So just to make sure, I understand this is replacing what you were using webpack for..."

Async Request APIs and Dynamic IO

Next.js 15 introduces async request APIs, a significant change aimed at streamlining how asynchronous data fetching is handled within the framework.

Jimmy Lai explains the motivation behind this change:

[24:11] Jimmy Lai: "...we wanted to come up with a single concept through which users could determine if their code was static or dynamic."

Key Points:

• Promises for Request Data: Methods like headers and cookies now return promises, requiring developers to await their resolution.

  [24:11] Jimmy Lai: "Calling headers would now return like a promise. Calling cookies would now return a promise..."

• Dynamic IO Concept: Introduced to simplify the framework's ability to distinguish between static and dynamic content based on asynchronous operations.

  [24:11] Jimmy Lai: "Dynamic IO is this... if your user code uses Promises, if you actually await for some asynchronous work, then NEXT can generally reason about it and say that this page should probably be dynamic."

• Enhanced Pre-rendering: Next.js can now intelligently pre-render pages at build time, defaulting to static rendering unless asynchronous operations indicate dynamic content.

  [29:09] Jimmy Lai: "Yep, that's perfect."

Next Form Component

Another noteworthy addition in Next.js 15 is the Next Form component, designed to simplify form handling within applications.

Tim Neutkens discusses its functionality:

[30:36] Tim Neutkens: "Next form really simple... it adds some additional features like prefetching and client-side navigation."

Key Points:

• Seamless Integration: Acts as a drop-in replacement for the standard <form> tag, automatically handling features like prefetching and navigation transitions.

• Developer Convenience: Reduces the need for manual handling of common form-related tasks, streamlining the development process.

  [31:27] Jimmy Lai: "The idea behind the component is that we wanted to make it as similar to the vanilla form as possible... just add a really thin layer that connects it to the Next.js router on its own."

Relationship with React

A significant portion of the discussion revolves around the evolving relationship between Next.js and React, especially concerning upcoming React 19 features.

Tim Neutkens sheds light on how Next.js integrates with React’s advancements:

[38:51] Tim Neutkens: "We're trying to make in essence... a lot of what we're doing now is actually bringing a lot of the learnings that we had from Next.js into the overall ecosystem."

Key Points:

• Collaborative Development: Close collaboration with the React team ensures that Next.js stays aligned with React’s roadmap and leverages its latest features.

• Server Components and Directives: Next.js utilizes React’s useClient, useServer, and useCache directives to manage server and client boundaries effectively.

  [38:09] Tim Neutkens: "...we support it with webpack as well. The main difference now is that with webpack we have to do manual bookkeeping between three different webpack instances... whereas now it's one compiler that can reason about the entire module graph."

• Enhancing React Features: Contributions such as improved head management and hydration error reporting benefit the broader React community.

  [43:15] Jimmy Lai: "We don't think about it just as Next.js... When we design server components, etc., it has to all go back to React itself."

Deployment and Vercel Integration

The conversation also touches on deploying Next.js applications, particularly the relationship with Vercel and efforts to support diverse hosting environments.

Jimmy Lai and Tim Neutkens discuss the challenges and solutions for deploying Next.js outside Vercel:

[45:03] Jimmy Lai: "Next.js on its own has always been pretty easy to self-host... but what's not worked real well out of the box is really that Next.js story as an infrastructure."

Key Points:

• OpenX Initiative: Working with the Open Next maintainers to standardize deployment processes across various platforms, making it easier to deploy Next.js applications on providers like AWS, Azure, and GCP.

  [48:18] Jimmy Lai: "...we can better avoid something like OpenX existing by taking their learnings and adapting it into our code base..."

• Documentation and Community Support: Efforts to enhance documentation and provide starter templates to simplify deployments on different hosting platforms.

  [46:16] Tim Neutkens: "...we're investing a lot of time into creating a set of community maintainers and we want to make sure we support everyone in the community in that regard."

• Self-Hosting Flexibility: While Vercel remains the optimal choice for seamless integration, Next.js 15 ensures robust support for self-hosted environments without compromising performance.

  [49:50] Tim Neutkens: "We just want to make sure that when you're self-hosting that's not a bad thing."

Future Directions and Final Thoughts

As the episode wraps up, Tim Neutkens emphasizes that upgrading to Next.js 15 is just the beginning:

[50:58] Tim Neutkens: "To Next.js 15, you're not done yet and try to render it back as well. It's opt-in still and the reason for that is that we don't have built yet, but what we've seen in our own apps and people reaching out to us is definitely going to give you a big performance boost for development."

Final Takeaways:

• Continuous Improvement: Next.js 15 sets the stage for ongoing enhancements, with TurboPack and other features continually evolving.
• Developer Empowerment: By addressing performance bottlenecks and simplifying complex tasks, Next.js 15 empowers developers to build faster and more efficiently.
• Community-Centric Approach: Emphasis on collaboration with the React team and the broader community ensures that Next.js remains at the forefront of web development frameworks.

Conclusion

Next.js 15 marks a significant leap forward for developers, introducing TurboPack, async request APIs, and the Next Form component, all aimed at enhancing performance and developer experience. The strong collaboration with the React team ensures that Next.js remains aligned with the latest advancements in the ecosystem. Additionally, efforts to streamline deployment across various platforms underscore Next.js's commitment to flexibility and scalability. As Jimmy Lai and Tim Neutkens highlight, Next.js 15 is both a culmination of extensive development and a foundation for future innovations in web application development.

Note: This summary excludes advertisements and non-content sections from the original transcript to maintain focus on the core discussion.