React 18: Must-Know Features & Upgrades for Beginners

What’s New in React 18: Key Features and Improvements

The frontend world is alive with anticipation — with the release of React 18, there are some pretty impactful changes coming for such a popular JavaScript library. Whether you are a seasoned React developer or just getting started, we want to bring you up to speed on all the coolest new parts (it’s not just new features either, this update promises to be more performant than ever)!

In this blog post, we will go over the new features of React 18, why they are important and how you can use them to your advantage in your projects. We’ll also give you some pointers on how to make a smooth migration to React 18. Let’s get started!

Introducing React 18

React has been the preferred framework for building modern web applications for quite some time now and with good reasons. It is fast, component based and has a huge ecosystem of tools and libraries that make developer's lives easier. However as web applications get more complex, developers have to face new challenges like dealing with more interactive UIs, improving performance or making the overall user experience smoother.

React 18 is expected to address all those problems. This release comes with a bunch of new features that improve concurrency, performance, and the overall developer experience, trying to make React apps faster without making developing them slower. But what are those new features introduced in React 18 that you should be excited about?

- New Concurrent Features: Making UIs Smoother

One of the biggest things in React 18 is concurrent rendering. It allows React to prepare multiple UI updates (we’ll call them “renders” for simplicity) at once, in the background, without blocking the main thread. As a result, UI feels faster and more responsive to input.

What's Different?

In previous versions of React, updates to the UI would happen in a synchronous way. One after the other. With concurrent rendering, React is now able to actually reason about which update is more important and should be prioritized first. That way for example urgent updates like typing in an input field can block more expensive non-urgent work like animations.

Example:

Imagine you have an app with a complex data table. In a synchronous app, if you updated a couple rows worth of data, the main thread would be blocked and your app would feel laggy. With concurrent rendering, React can update only the rows of the table that were actually updated in the background while keeping everything else interactive.

- Automatic Batching for Better Performance

In React 18, automatic batching now extends to more asynchronous operations. Batching is the ability to put multiple state updates into a queue, so that React can re-render once. While this worked within React event handlers in previous versions of React, any async update (e.g., timeouts or promises) caused double rendering.

React 18 solves this via automatic batching of updates coming from asynchronous events. It significantly reduces unnecessary renders in your application hence making it performant.

Example:

It makes state management less complex and your app performant even when working with async operations.

- The useTransition Hook: Prioritize Updates for a Smoother UI

Another new feature in React 18 is the useTransition hook. It lets you tell React that some updates are “transitions” and not as high priority. React will work on those updates in the background while prioritizing rendering of more important state updates, such as user interactions.

Why It’s Useful:

Let’s say you have a complex data-heavy dashboard that updates every time a user selects a filter. Instead of making the whole app feel sluggish with each filter change, you can use useTransitions to make the filter update a background task, and users can still interact with other parts of the app without delays.

Example:

UseTransition hook is the key to build applications that will feel more responsive even if you have large data in your hand.

- Updates to Suspense: Making Asynchronous Code Simpler

React’s Suspense feature was implemented for handling asynchronous code like data fetching. And in React 18, it will be possible to use Suspense with Server-Side Rendering (SSR), making data fetching easier and faster.

What’s New in React 18?

In the previous releases, Suspense was mostly responsible for lazy-loading components. However, in React 18 we can leverage it to seamlessly support async data-fetching as well which will reduce complexity and improve performance.

Example:

Think of a user’s profile page where you fetch data from multiple sources (user info, posts, comments). Due to Suspense you can create loading states for each part of the UI so that users get better experience while they’re waiting for the data to load.

With Suspense, you can keep the app feeling snappy and responsive, even when waiting for data to load.

Migrating your app to React 18 doesn’t have to be hard. Here’s some advice on how to do it smoothly.

• Upgrade Dependencies: Ensure that your React related dependencies (like React Router or Redux) are compatible with React 18.
• Test Key Features: First, test the new features e.g. concurrent rendering and useTransition in a separate branch to see if it affects your app.
• Use the New createRoot API: In React 18, it’s recommended to use the createRoot API instead of the old ReactDOM.render. This sets your app up for future improvements.

• Check for Deprecated Features: Review any deprecated APIs that may be impacted by the upgrade and replace them with the newer alternatives.

Conclusion: Why React 18 is a Big Deal

React 18 comes with a host of new features that make developing modern web apps easier, faster, and more fun. From concurrent rendering to automatic batching, the useTransition hook, and improved Suspense, React 18 will scale your web app’s performance and user experience to new heights.

If you’re planning to build highly interactive and performant web applications, there is no doubt you should consider upgrading to React 18. The new features not only enhance the user experience but also simplify the whole development process by reducing boilerplate code.

I hope this helped you understanding what’s new in React 18! We will keep sharing updates about these and other topics with best practices for modern frontend development. So stay tuned!