ReactJS

React Conf 2024 Review

Published Jun 5, 2024

Updated Jun 5, 2024

6 min read

A lot has happened since the last React Conf, so 2024 was action-packed. The conference lasted two days in Las Vegas and was focused on all the new stuff coming with React v19. Day one was centered around React 19/Server Components, and day two was React Native. There were some exciting reveals, fantastic talks, and demos.

This post will cover the conference's big news, specifically the main keynotes from days 1 and 2.

Day 1 Keynote

The main keynote included several speakers from the React team, and early in the talk they mentioned a goal of “Make it easy for anyone to build great user experiences.” This sounds great but I was curious to see exactly what they meant by this since it seems like React has arguably gotten more complex with the introduction of Server Components and related API’s.

The keynote was split into 3 sections:

State of React - Lauren Tan

Lauren shared the staggering adoption React has received over the years and thanked all the contributors and the community. She also highlighted the amazing ecosystem of packages, tools, and frameworks.

It’s hard to argue against these points, but React seems to be in a weird in-between state. The framework is headed in this new direction but doesn’t feel quite there yet.

React 19

A few team members collaborated on a walkthrough of React 19, which included all the new features and a bunch of quality-of-life improvements.

The main highlights were:

Server Rendering & Suspense - One of the coolest bits was showing how to co-locate and load stylesheets and other assets in components. “HTML Composition for Bundlers, Libraries, & Apps”
Hydration - This was a fan favorite, and the TL;DR is fewer hydration errors with better messages and debuggability.
Actions - This is one of my favorite new features, as it feels like something that was missing from the React toolkit for a long time. The new Actions API is a “First-class pattern for asynchronous data updates in response to user input”. It includes Remix inspired form behaviors and API’s that replace a lot of boilerplate for handling async operations like loading and error states.
JSX Improvements

One of the most applauded announcements was the changes to refs, which are now automatically passed to every component 🙌

React Compiler !!

Yes, we’ve all heard the news by now. They are finally open sourcing the compiler that they teased over 2 years ago. React compiler understands React code/rules and is able to automatically optimize/memoize our application code.

One of the big complaints of React has long been that there’s a lot of mental overhead and thought that needs to be put into optimizing and building fast components. So, the goal is to remove that burden from the developers so that they can focus on writing their business logic.

One of the slides mentioned that the compiler has the following behaviors: Dead Code Elimination, Constant Propagation, Type Inference, Alias Analysis, Mutable Lifetime Inference, HIR, and Diagnostics. I’m not going to pretend to know all those things, but I’ve already heard a lot of positive feedback about how it works and how advanced it is.

The team mentioned that they are already running the compiler in production on Instagram.com and some of their other websites.

Day 2 Keynote

Day 2 opened with sharing the incredible growth in downloads and adoptions that React Native has had (78M downloads in 2023). They shared some meta info about the recent releases and talked about all the partners helping to push the framework forward. They mentioned the Meta investment in React Native and shared about some of the ways that they are using it internally in places like Facebook Marketplace.

Next they shared about all the work that Microsoft is doing with React Native for things like supporting building Windows apps with React Native. I was surprised to learn that the Windows Start Bar is a React Native app 🤯.

New Architecture

"Rewrite React Native to be synchronous so it’s possible to be concurrent"

I was surprised when I read this since these two things seem to conflict with one another. The new architecture allows for the concurrent mode in React.

This section opened by describing the original architecture of React Native (JavaScript code with a bridge for passing information back and forth from the native layer)

The new architecture replaces “the bridge” with a concept called “JSI (JavaScript Interface)”. Instead of message passing, it uses memory sharing between the JS and Native layers.

The big announcement was that the new architecture has been moved into Beta and they have released a bunch of things to help with compatibility between the old and new architecture to minimize breakages when upgrading.

Production Ready Apps

The section opened by talking about all the complexities and pieces involved with shipping a high-quality app to Android and iOS. If you’re a mobile developer, you know it’s quite a lot. They highlighted a new section of the documentation that provides details about “React Native Frameworks”. They are recommending using a “Framework” with React Native, just like they are recommending for React on the web.

I had never even considered the idea of a “React Native Framework” before, so I thought that was pretty surprising. I guess it makes sense that Expo is a Framework but I’m not aware of any others like it.

So the recommendation from the React Native documentation is: “Use Expo”. Which leads to the next part of the keynote….

Expo

This part of the talk went more in-depth on a lot of the complexities with mobile development that Expo helps you solve. They highlighted an amazing suite of modules that they have dubbed the “Expo SDK”. The SDK consists of well-defined modules that handle some type of integration with the underlying Native platforms. They also have a Modules API to help build your own Native modules.

Another new feature that I wasn’t aware of is API routes with Expo Router. How does that even work???

The next thing they mentioned was a feature called CNG (Continuous Native Generation). I’ve played with this a bit and it’s pretty nice. Expo will generate the iOS and Android projects/code that is needed to build the final application. The sales pitch is that this will help with upgrades if you aren’t managing and changing your native code by yourself. If you’ve upgraded a React Native app before you know how painful this can be.

I am interested to see if CNG is practical in the real world. In my experience most projects have ended up ejected from expo and require managing your own native code.

This section wrapped up with talking about builds and deployments with Expo Application Services (EAS). I don’t have experience with EAS yet personally but builds and deployments have always been the biggest pain point in my experience. I would definitely give it a try on my next project.

As someone who has worked with React Native and Expo quite a bit over the years, it truly has come a really long way. Expo is amazing.

Summary

There were a ton of really exciting announcements and content just between the two keynotes. My impression from the conference is that a new era of React is kicking off and it’s really exciting. I’d hate to be one of the people betting against React as they’ve shown time and time again that they are willing to take risks and innovate in this space. It’s going to be a busy year in the React ecosystem as more frameworks adopt Server Components and more applications give it a try.

There were a bunch of other really incredible talks in the conference and I’m really excited to write about a couple of them in particular. I wish I could have attended in person but the live stream didn’t disappoint!

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About the author(s)

Dane Grant
JavaScript developer building things on web, native, and server environments. Free time filled with reading, cooking, dog, sports, comedy, and music.
@danecando @danecando

Communication Between Client Components in Next.js

Communication Between Client Components in Next.js In recent years, Next.js has become one of the most popular React frameworks for building server-rendered applications. With the introduction of the App Router in Next.js 13, the framework has taken a major leap forward by embracing a new approach to building web applications: the concept of server components and client components. This separation of concerns allows developers to strategically decide which parts of their application should be rendered on the server and which are then hydrated in the browser for interactivity. The Challenge: Communicating Between Client Components While server components offer numerous benefits, they also introduce a new challenge: how can client components within different boundaries communicate with each other? For instance, let's consider a scenario where you have a button (a client component) and a separate client component that displays the number of times the button has been clicked. In a regular React application, this would typically be accomplished by lifting the state to a common ancestor component, allowing the button to update the state, which is then passed down to the counter display component. However, the traditional approach may not be as straightforward in a Next.js application that heavily relies on server components, with client components scattered across the page. This blog post will explore three ways to facilitate communication between client components in Next.js, depending on where you want to store the state. Lifting State to a Common Client Component One approach to communicating between client components is to lift the state to a common client component. This could be a React context provider, a state management system like Zustand, or any other solution that allows you to share state across components. The key aspect is that this wrapper component should be higher up in the tree (perhaps even in the layout) and accept server components as children. Next.js allows you to interleave client and server components as much as you want, as long as server components are passed to client components as props or as component children. Here's how this approach might look in practice. First of all, we'd create a wrapper client component that holds the state: ` This wrapper component can be included in the layout: ` Any server components can be rendered within the layout, potentially nesting them several levels deep. Finally, we'd create two client components, one for the button and one for the counter display: ` ` The entire client and server component tree is rendered on the server, and the client components are then hydrated in the browser and initialized. From then on, the communication between the client components works just like in any regular React application. Check out the page using this pattern in the embedded Stackblitz window below: Using Query Params for State Management Another approach is to use query params instead of a wrapper client component and store the state in the URL. In this scenario, you have two client components: the button and the counter display. The counter value (the state) is stored in a query param, such as counterValue. The client components can read the current counter value using the useSearchParams hook. Once read, the useRouter hook can update the query param, effectively updating the counter value. However, there's one gotcha to this approach. If a route is statically rendered, calling useSearchParams will cause the client component tree up to the closest Suspense boundary to be client-side rendered. Next.js recommends wrapping the client component that uses useSearchParams in a boundary. Here's an example of how this approach might look. The button reads the current counter value and updates it on click by using the router's replace function: ` The counter display component is relatively simple, only reading the counter value: ` And here is the page that is a server component, hosting both of the above client components: ` Feel free to check out the above page in the embedded Stackblitz below: Storing State on the Server The third approach is to store the state on the server. In this case, the counter display component accepts the counter value as a prop, where the counter value is passed by a parent server component that reads the counter value from the database. The button component, when clicked, calls a server action that updates the counter value and calls revalidatePath() so that the counter value is refreshed, and consequently, the counter display component is re-rendered. It's worth noting that in this approach, unless you need some interactivity in the counter display component, it doesn't need to be a client component – it can be purely server-rendered. However, if both components need to be client components, here's an example of how this approach might look. First, we'll implement a server action that updates the counter value. We won't get into the mechanics of updating it, which in a real app would require a call to the database or an external API - so we're only commenting that part. After that, we revalidate the path so that the Next.js caches are purged, and the counter value is retrieved again in server components that read it. ` The button is a simple client component that calls the above server action when clicked. ` The counter display component reads the counter value from the parent: ` While the parent is a server component that reads the counter value from the database or an external API. ` This pattern can be seen in the embedded Stackblitz below: Conclusion Next.js is a powerful framework that offers various choices for implementing communication patterns between client components. Whether you lift state to a common client component, use query params for state management, or store the state on the server, Next.js provides all the tools you need to add a communication path between two separate client component boundaries. We hope this blog post has been useful in demonstrating how to facilitate communication between client components in Next.js. Check out other Next.js blog posts we've written for more insights and best practices. You can also view the entire codebase for the above snippets on StackBlitz....

Jun 21, 2024

5 mins

NextJSReact

Remix's evolution to a Vite plugin

The Remix / React Router news is a beautiful illustration of software evolution. You start with a clear idea of what you’re building, but it’s impossible to anticipate exactly what it will become. If you haven’t heard the news yet, Ryan Florence announced at React Conf 2024 that Remix will be a Vite plugin for React Router. It’s a sort of surprising announcement but it makes a lot of sense if you’ve been following along as Remix the project has evolved. In this post we’ll recap the evolution of the project and then dig into what this change means for the future of Remix in the Server Components era of React. 🗓️ October 2021 > Remix is open sourced In the beginning, Remix cost money. In October 2021 they received some seed funding and the project was open sourced. Remix was an exciting new framework for server-rendering React websites that included API’s for loading data on the server and submitting data to the server with forms. It started a trend in the front-end framework space that a lot of other popular frameworks have modeled after or taken inspiration from. 🗓️ March 2022 - September 2022 > Remixing React Router At some point they realized that the API’s that they had created for Remix were a more natural fit in React Router. In this post Ryan details the plans to move these Remix API’s into React Router. Several months later, React Router 6.4 is released with the action, loader, and other Remix API’s baked in. > "We've always thought of Remix as "just a compiler and server for React Router" After this release, Remix is now mostly as they described - a compiler and server for React Router. 🗓️ October 2023 - February 2024 > Remix gets Vite support If you’re not familiar with Vite, it’s an extremely popular tool for front-end development that handles things like development servers and code bundling/compiling. A lot of the modern front-end frameworks are built on top of it. Remix announced support for Vite as an alternative option to their existing compiler and server. Since Remix is now mostly “just a compiler and server for React Router” - what’s left of Remix now that Vite can handle those things? 🗓️ May 2024 > Remix is React Router The Remix team releases a post detailing the announcement that Ryan made at React Conf. Looking back through the evolution of the project this doesn’t seem like an out of the blue, crazy announcement. Merging Remix API’s into React Router and then replacing the compiler and server with Vite didn’t leave much for Remix to do as a standalone project. 🐐 React Router - the past, present, and future of React React Router is one of the oldest, and most used packages in the React ecosystem. > Since Remix has always been effectively "React Router: The Framework", we wanted to create a bridge for all these React Router projects to be able to upgrade to Remix. With Remix being baked into React Router and now supporting SPA mode, legacy React Router applications have an easier path for migrating to the next generation of React. https://x.com/ryanflorence/status/1791488550162370709 Remix vs React 19 If you’ve taken a look at React 19 at all, it turns out it now handles a lot of the problems that Remix set out to solve in the first place. Things like Server Components, Server Actions, and Form Actions provide the same sort of programming model that Remix popularized. https://x.com/ryanflorence/status/1791484663883829258 Planned Changes for Remix and React Router Just recently, a post was published giving the exact details of what the changes to Remix and React Router will look like. tl;dr For React Router * React Router v6 to v7 will be a non-breaking upgrade * The Vite plugin from Remix is coming to React Router in v7 * The Vite plugin simply makes existing React Router features more convenient to use, but it isn't required to use React Router v7 * v7 will support both React 18 and React 19 For Remix * What would have been Remix v3 is React Router v7 * Remix v2 to React Router v7 will be a non-breaking upgrade * Remix is coming back better than ever in a future release with an incremental adoption strategy enabled by these changes For Both * React Router v7 comes with new features not in Remix or React Router today: RSC, server actions, static pre-rendering, and enhanced Type Safety across the board The show goes on I love how this project has evolved and I tip my hat to the Remix/React Router team. React Router feels like a cozy blanket in an ecosystem that is going through some major changes which feels uncertain and a little scary at times. The Remix / React Router story is still being written and I’m excited to see where it goes. I’m looking forward to seeing the work they are doing to support React Server Components. A lot of people are pretty excited about RSC’s and there is a lot of room for unique and interesting implementations. Long live React Router 🙌....

Jul 10, 2024

4 mins

ReactViteRemix

The CSS / Utility hybrid approach with Tailwind v4

Just recently, the progress on the next major version of Tailwind CSS was open-sourced, along with a preview post. This is very exciting news to me, and I love the direction they’ve taken with this release. Tailwind can be a pretty polarizing topic among developers, but I believe that we can find some common ground and live in harmony. In this post, we’ll look at how the CSS + Tailwind hybrid approach is getting an upgrade in v4 and some of the patterns that we can take advantage of to provide a stellar styling experience on our websites. The hybrid approach It doesn’t matter what your personal take on Tailwind is, the fact is utility classes are an incredibly useful pattern for styling websites with CSS. I’m not sold on the hard-line, all-or-nothing approach that Tailwind has always recommended. Having a class string that extends way off the screen on an ultra-wide monitor is not pretty. Combining traditional CSS classes with utility classes helps cut down on the styling noise in your markup and provides some advantages when applied correctly. This post will cover some useful patterns and best practices for using CSS and Tailwind in harmony Tailwind going “CSS-native” In the v4 introduction post, they state A major goal of Tailwind CSS v4.0 is making the framework feel CSS-native, and less like a JavaScript library. I love that they are heading in this direction, and I’m imagining Tailwind as the toolkit for styling websites with CSS. It is going to replace the plethora of tools from the past and provide support for all the modern niceties like: * Importing CSS files with @import * Vendor prefixing _(no more autoprefixr)_ * Improved browser support for modern features like CSS nesting and media query ranges. This means less worry for us as developers. We can write our code and build our sites using the modern features that the platform provides without sweating all the other details and edge cases. The talented folks at Tailwind and the open-source community have our backs. Tailwind v4 CSS configuration The biggest step in the “CSS-native” direction and the feature that I’m most excited about is the CSS configuration. This is great for embracing CSS and Tailwind as one instead of two factions at battle. If you’ve been using Tailwind exclusively for a long time like I have, you might be out of touch with all the great features and tools that CSS provides out of the box now. This is a great opportunity to get back to learning and using the platform. In Tailwind v4 we do our configuration and theming with CSS variables. To get an idea of what this looks like check out the default theme on GitHub. In our configuration we can override any values from the default theme or extend it with new values. ` All the values from the theme are exposed as CSS variables. We can reference them in our CSS files or directly in our utility classes. ` ` Best practices for combining CSS with utility classes I can understand why Tailwind recommends using strictly utility classes. It’s easy to shoot yourself in the foot and run into the issues that utility classes set out to solve in the first place. I believe if you follow some general guidelines you can safely have the best of both worlds. Create focused/specialized classes CSS tends to get messy when we use classes that are overly specific with styles that apply to just one or a small number of use cases. Take a calendar where the days are custom checkboxes. You might have some pretty specialized styles for this bit of UI. ` Notice that we just add some specific styles that apply to this use case. This gives us the flexibility to keep composing our styles with utility classes. Some things are better left to utilities The best way to avoid wandering too far off the path of enlightenment is to stick with utility classes for certain (most?) things. Spacing and layouting are examples of things that are probably best left to utility classes. These typically vary all across a page, and encoding them in a class will make it a lot less flexible. A code smell to look out for: If you have abstracted something to a class and you end up overriding certain aspects of its styles in different places. Those styles should probably be utility classes. Classes as components Tailwind has always recommended using a component system for your UI components so that your utility classes are all defined in a single place. You don’t want to have to edit 50 different files to make a change to the style of your buttons across your website. I’ve found that defining things that might be simple “components” like buttons, badges, links, etc as classes works just as well in most cases. You can use Tailwind CSS with the @apply directive or traditional class definitions for this: ` You can even bring the BEM naming convention back to compose variants on top of base component styles. (or name them however you’d like!) ` Now we can easily define badges in our markup: ` Modern CSS and other interesting utility hybrid patterns I think a lot of us are realizing that modern CSS is pretty great. There are a ton of awesome new features gaining support across major browsers, like CSS nesting, container queries, and more! More and more people are also coming around to the utility of utility classes. If you want to dive deeper and see other interesting approaches and patterns when combining modern CSS with utility classes, check out the post: Modern CSS patterns in Campfire. Summary I’m looking forward to the Tailwind CSS configuration and other awesome updates coming in v4. Using Tailwind doesn’t have to be a one-size-fits-all approach. If you want to write some CSS, I say go for it! Hopefully, some of the points in this post will lead to success if you decide to do so....

May 10, 2024

4 mins

Tailwind CSSCSS

Understanding the Difference Between `:focus` and `:focus-visible` in CSS

Understanding the Difference Between :focus and :focus-visible in CSS I have learned my fair share about the importance of keyboard accessibility, so I know that visual indication of the focused element is very important. But the well-known :focus pseudo-class is not always the best fit for this job. That's where :focus-visible comes in. Let's look at the differences between these two pseudo-classes and explore the best practices for using them effectively. What is the :focus Pseudo-Class? The :focus pseudo-class is a CSS selector that applies styles to any element that receives focus, regardless of how that focus was triggered. This includes focus events from keyboard navigation, mouse clicks, and touch interactions. Example Usage of :focus ` In this example, the button will display a blue outline whenever it is focused, whether the user clicks on it with a mouse, taps it on a touchscreen, or navigates to it using the keyboard. What is the :focus-visible Pseudo-Class? The :focus-visible pseudo-class is more specialized. It only applies styles to an element when the browser determines that the focus should be visible. This typically occurs when the user navigates via the keyboard or assistive technologies rather than through mouse or touch input. Example Usage of :focus-visible ` Here, the button will only show a blue outline when focused through keyboard navigation or another input method that usually requires visible focus indicators. Key Differences Between :focus and :focus-visible :focus - Behavior: Applies to any element that receives focus, regardless of the input method. - Use Cases: Ensures that all interactions with the element are visually indicated, whether by mouse, keyboard, or touch. :focus-visible - Behavior: Applies styles only when the focus should be visible, such as using a keyboard or assistive technology. - Use Cases: Ideal for scenarios where you want to provide focus indicators only to keyboard and assistive technology users while avoiding unnecessary outlines for mouse and touch users, typically required by design. Accessibility Implications :focus - Pros: - Guarantees that all users can see when an element is focused, which is critical for accessibility. - Cons: - Can lead to a suboptimal experience for mouse users, as focus styles may appear unnecessarily during mouse interactions. :focus-visible - Pros: - Enhances user experience by showing focus indicators only when necessary, thus keeping the interface clean for mouse and touch users. - Tailors the experience for keyboard and assistive technology users, providing them with clear visual cues. - Cons: - Additional considerations may be required to ensure that focus indicators are not accidentally omitted, especially in older browsers that do not support :focus-visible. - There may be cases where you want to show focus indicators for all users, regardless of input method. Best Practices for Using :focus and :focus-visible To achieve the best accessibility and user experience, combining both :focus and :focus-visible in your CSS is often a good idea. Combining :focus and :focus-visible ` Here is a Stackblitz example of what such styling could look like for you to try out and play with. Additional Tips - Test with Keyboard and Assistive Technology: Ensure that your web application is navigable using a keyboard (Tab, Shift + Tab, etc.) and that focus indicators are visible for those who rely on them. It's never a bad idea to include accessibility testing in your e2e testing suite. - Provide Clear Focus Indicators: Make sure that focus indicators are prominent and easy to see. A subtle or hard-to-spot focus indicator can severely impact accessibility for users who rely on keyboard navigation. Conclusion The :focus-visible pseudo-class offers a more refined way to manage focus indicators, improving accessibility and user experience, particularly for keyboard and assistive technology users. By understanding the differences between :focus and :focus-visible, and applying best practices in your CSS, you can create more accessible and user-friendly web applications. Remember, accessibility should never be an afterthought. By thoughtfully applying focus styles, you ensure that all users, regardless of how they interact with your site, can easily navigate and interact....

Nov 8, 2024

3 mins

AccessibilityCSSPlaywright

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React Conf 2024 Review

Day 1 Keynote

State of React - Lauren Tan

React 19

React Compiler !!

Day 2 Keynote

New Architecture

Production Ready Apps

Expo

Summary

Dane Grant

You might also like

Communication Between Client Components in Next.js

Remix's evolution to a Vite plugin

The CSS / Utility hybrid approach with Tailwind v4

Understanding the Difference Between `:focus` and `:focus-visible` in CSS

Let's innovate together!

You might also like

Communication Between Client Components in Next.js

Remix's evolution to a Vite plugin

The CSS / Utility hybrid approach with Tailwind v4

Understanding the Difference Between `:focus` and `:focus-visible` in CSS