React is a widely-used front-end JavaScript library for developing creative UI interfaces with various components. It facilitates efficient updates and renders necessary changes in real-time while debugging codes on a large scale. React is commonly used to create the view level of web applications, and it requires both npm and Nodejs to be installed for production-level usage.
React 18 brings new updates to the library, and this article will explore them in-depth. React is a popular coder language, holding around 40% of the web development technology market share. It is suitable for developing large react web applications that can update data without causing delays. Overall, React is a simple and scalable language for web development. To gain a deeper understanding of React, click the link provided for expert guidance on how to learn React JS.
React 18 was released in March 2022 and has several new features and improvements that benefit users and developers. This blog will cover these features, how they can be implemented, and the React team’s plans for the framework.
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What is New in React 18?
React 18, the latest version of React comes with improved functionality to overcome the limitations of the previous version. It offers excellent functional dependencies that enhance performance and simplify development for programmers.
React 18 is ideal for designing creative APIs and rendering HTML files, with a vast collection of libraries from experts and authors providing valuable inputs to developers. With the help of web application development services, developers can showcase their creative abilities online.
React JS development is also a popular choice for building web applications, and businesses can hire React JS developers to create robust and scalable solutions. React 18 offers new features and enhancements, making it an attractive option for developers seeking to build powerful web applications.
React 18 Features
1. Concurrent React
React 18 has introduced a new concurrent rendering engine, which has been optimized for both front-end and server-side rendering. This engine uses concurrency to improve the process of rendering the UI on both the server and client sides, resulting in a smoother user experience even on heavy data-centric pages. This enhanced rendering engine is implemented as part of the improved <Suspense> component, which allows developers to use data fetching with fewer complexities. With this new engine, users can interact with the page sooner, providing a better overall experience.
In React, when a user switches between tabs and returns to the original tab, the previous screen is restored to the same state. React 18 introduces a new component called <Offscreen> to implement this pattern. React can more efficiently manage the components’ offscreen state with this new component, allowing smoother transitions when switching between tabs. Overall, this enhancement improves the user experience and helps to create more fluid web applications.
2. Server Side <Suspense> Components
React’s Suspense component allows developers to pause the rendering of a component until a specified condition is met, with an option for a fallback component, such as a spinner or a string. Previously, Suspense only worked with dynamic importing or lazy loading.
Server-side rendering (SSR) is achievable in React by first rendering all components on the server and sending the resulting HTML elements to the browser. The JavaScript bundle is then loaded in the browser and connected to the HTML components.
With server-side rendering, users can view page content before the JavaScript bundle loads and runs. React introduced the suspense feature in version 16.6, which allows for the postponement of component rendering with basic support and some limitations.
The stable release of React 18 will include a complete suspense feature based on the concurrent feature, along with additional features such as:
Delayed Transition:
It instructs components to delay creating a new state transition until the data has been resolved.
Placeholder:
Throttling reduces UI thrashing by slowing down the visibility of nested placeholders and subsequent components.
Suspendlist:
This feature helps suspend multiple components by organizing them in the order they must be revealed to the user. These new features will improve the performance and user experience of web applications built with React 18.
React version 18 has changed how it handles suspense compared to previous versions. However, these changes have minimal impact on app migration thanks to automatic batching. In earlier versions, such as React 16 and 17, the suspense was called legacy suspense. In React 18, an improved and enhanced version of suspense called concurrent suspense has been introduced.
React’s legacy and concurrent suspense features provide a similar user experience, as demonstrated in the example where both resolve the “ComponentThatSuspends” function.
<Suspense fallback={<Loading />}>
<ComponentThatSuspends />
<Sibling />
</Suspense>
The above example demonstrates the functioning of the suspense component in React version 18:
- In the case of the legacy suspense, the Sibling component will be mounted to the DOM immediately, and its lifecycle hooks/effects will be triggered. It will not wait for the resolution of “ComponentThatSuspends” before proceeding.
- In contrast, with the concurrent suspense in React 18, the Sibling component will not be mounted to the DOM until the “ComponentThatSuspends” is resolved, and its lifecycle hooks/effects will not be triggered. This new feature effectively resolves all of the issues associated with legacy suspense.
3. Streaming Server Rendering (SSR)
Server rendering is a technique where React component’s HTML output is rendered and shown to users before the JavaScript is ready. Before React 18, this approach was all-or-nothing, meaning that the user had to wait until all components were available before interacting with the application. If there was a single slow component, like a complex data grid, it could become a bottleneck.
React 18 introduces Suspense, enabling us to designate fallbacks for UI elements that haven’t appeared on the screen. By wrapping a slow component with the <Suspense> tags, we can delay its loading and configure a fallback to show a loading animation. Instead of waiting for everything to be ready, the user can see the page’s content as soon as it’s available. You can immediately display the initial HTML and stream the rest, resulting in a faster and smoother user experience.
4. Improvement in Automatic Batching
Batching is an essential feature in React that groups state updates using built-in hooks and event handlers, preventing unnecessary component re-renders and improving performance. In earlier versions of React, such as version 17, batching was only available for browser events. However, with the new release of React 18, Automatic Batching has been introduced, providing an improved version of batching.
Automatic Batching allows batching for all state updates from “createRoot,” regardless of their origin. This includes batch state changes, intervals, native event handlers, asynchronous operations, and timeouts.
React 17 Automatic Batching:
function App()
{//Declaring state values.
Const [count, setCount] = useState(0);
const [flag, setFlag] = useState(false);
// Change state on button click.
function handleClick() {
setCount(c => c + 1); // Does not re-render yet
setFlag(f => !f); // Does not re-render yet
// React will only re-render once at the end (that’s batching!)
}
return (
<div>
<button onClick={handleClick}>Next</button>
<h1 style={{ color: flag ? “blue” : “black” }}>{count}</h1>
</div>
);
}
With React 18, developers can now use batch state updates in response to browser events and inside setTimeout, native event handlers, promises, and other types of events. This new feature allows for more efficient state management and improved app performance.
5. Stopping Automatic Batching with flushSync()
Automatic batching in React 17 and earlier versions helped prevent unnecessary component re-rendering. However, in cases where code relies on reading from the DOM when the state changes, automatic batching can cause issues. To address this, React 18 provides a way to disable automatic batching using “ReactDOM.flushSync()“. This allows developers to control when state updates should be batched and when they should be executed synchronously.
import {flushSync} from ‘react-dom’; // Note: from react-dom, not React
function handleClick() {
flushSync (() => {
setCounter (c => c + 1);
});
//React has updated the DOM by now
flushSync (() => {
setFlag(f => !f);
});
//React has updated the DOM by now
}
6. Using Transitions to Prioritize UI Changes
| Urgent vs Non-Urgent UI Updates | ||
|---|---|---|
|
|
Expectation |
Examples |
|
Urgent |
User expect the changes to be more or less instantaneous. |
Immediate UI changes e.g. changing the value of an input field or selecting from a drop-down. |
|
Not Urgent |
Users will wait for a few seconds before getting frustrated. |
Changes the user does not expect to be immediate e.g., the query results from a search field. |
React has introduced a new transition feature to differentiate between important and less important updates. This feature helps developers prioritize updates expected to have a greater impact on user interactions.
Important updates are direct interactions, such as clicking, pressing, or typing, while less important updates transition the user interface from one view to another.
Users are generally more tolerant of transition updates because they understand that their actions, such as navigating between pages, may not result in an immediate on-screen response.
When users interact with a drop-down menu, they expect to see it open instantly, even if there is a slight delay in loading the menu’s content, which is acceptable. Users are usually more tolerant of non-urgent updates, such as transitioning from one screen to another, as they understand it may take some time.
To provide the best user experience, developers can use React’s start transition API within an input event to categorize updates as urgent or non-urgent. This way, single user input can result in both updates.
import {startTransition} from ‘react’;
// Urgent: Show what was typed
setInputValue(input);
//Mark any state updates inside as transitions
startTransitions (() => {
// Transition: Show the results
setSearchQuery(input);
});
In React 18, non-urgent updates are wrapped inside the start transition API. These updates will only be interrupted if there is an urgent update from the user’s side, such as click events or keypresses. React will abandon the incomplete mid-rendering task if an interruption occurs and focus on rendering the most recent urgent update, ensuring a smooth user experience.
React 18 provides two ways to initiate transitions:
- Transition Hook: This hook includes a value for tracking the pending state and can be used to start transitions.
- startTransition API: This approach can be used to start transitions when hooks are not available.
7. Update Client Rendering APIs
React 18 has redesigned its APIs to render on both the client and the server side. The new APIs enable users to use the old React 17 interfaces while upgrading to React 18’s APIs.
React DOM Client
Experts in “react-dom/client“, on new APIs.
createRoot:
This new method allows you to create a “root” to “unmount“, or “render”. This method can be used in place of ReactDOM.render. It is required to use new features in React 18.
hydrateRoot:
This is a new way to hydrate an application rendered on a server. It can be used in place of the “ReactDOM.hydrate“, in conjunction with React DOM Server’s new APIs. It’s required for new features in React 18.
If you wish to be notified when React recovers from errors during hydration or rendering for logging, both “createRoot” and “hydrateRoot” go for a new option called “onRecoverableError“. React uses “reportError” as a default, or “console.error“, in older browsers.
React DOM server
“react-dom/server” offers new APIs for streaming Suspense and full support on the server.
renderToPipeableStream:
Node is used for streaming in Node environments.
renderToReadableStream:
This is for modern edge runtime environments, such as Deno and Cloudflare Workers.
Although it has been discouraged, the “renderToString method” is still available.
8. New Strict Mode Behaviors
React 16.3 brought a Strict Mode for the React Community. The tool was used for defining the coding patterns which could cause problems with the React concurrent rendering APIs. The tool runs in development mode and provides error messages or code recommendations to help developers improve the code.
When developers add ” It gives each component a unique behavior. When developers run React in “<StrictMode>“, React will re-render all components to remove any potentially harmful effects.
React Mounts Components:
- Create layout effects
- Create effects.
React Simulates the Unmounting of the Component:
- Layout effects have been destroyed.
- The effects are destroyed.
React Simulates Mounting a Component in the Previous State:
- Create layout effects
- Run the Effect Setup Code
9. New Hook
React 18 also has new hooks available for React developers. React hooks have been available since October 2018. New hooks allow developers to create class-based components instead. It also encourages React developers to build their entire app using React functional components. It allows developers to use simpler scripts that perform the same functions more efficiently and quickly.
React 18 has introduced many new hooks, including:
“useTransition“
“startTransition“, “useTransition“, and “convertTransition” which do not consider state updates urgent. By default, all other state updates will be regarded as urgent. React allows non-urgent updates to state (for instance, rendering search results in a list) to be interrupted when urgent updates are made (for instance, changing the text input).
“useId“
“useId“, a new hook, prevents hydration mismatches and produces unique IDs for both client and server. This is especially useful for component libraries that must integrate with APIs requiring unique IDs. This fix fixes a React 17 issue, but is even more important in React 18 because of the out-of-order HTML delivery by the new streaming server rendering.
“useDeferredValue“
Use “useDeferredValue“, to delay re-rendering of a component that is not urgent. This works in a similar way to debouncing but has a few benefits. React will try the deferred rendering immediately after the original render has been reflected on screen because there isn’t a predetermined time delay. The user can make a selection, and the deferred rendering is not interrupted.
“useSyncExternalStore“
The new hook “useSyncExternalStore” forces synchronous updates to external stores, allowing for concurrent reads. It removes the need for “useEffect“, when creating external data subscribers and is recommended for libraries that integrate with states outside of React.
“useInsertionEffect“
The “useInsertionEffect“, hook, helps CSS-inJS libraries handle performance issues with injecting styles into the render. This hook is not required until there’s a CSS in the JS library. This hook will be executed once the DOM has been changed but before the layout effects are able to read the updated layout. This fixes a problem that existed in the previous React version 18 and is now more critical in React 18 as React yields during concurrent rendering to allow it to recalculate.
React v18.0 impressed you, right? What’s holding you back?
Planning to Upgrade Your React JS Application?
How to Upgrade to React 18?
React is a renowned JavaScript library used for building user interfaces, with version 18 recently being released and offering many new features and enhancements. If you’re running an older version of React, upgrading to React 18 could enable you to take advantage of its new features and enhance the performance of your application. But how can I upgrade? This post will walk you through the steps needed to upgrade your React application to React 18. Before we proceed, it is important to remember that React 18 is not a major release but instead serves as an interim version that brings new features and enhancements without impacting existing codebases – meaning upgrading to React 18 won’t pose any serious risk to existing projects.
Step 1: Upgrade Your React Version
Before upgrading to React 18, it is essential that you use React version 17. If you are currently running older versions of React, version 17 needs to be upgraded, as React 18 is built upon version 17. For proper functioning.
To upgrade to React 17, use this command:
npm install react@^17.0.0 react-dom@^17.0.0
Step 2: Install the latest alpha version of React
React 18 Alpha is now available on npm and to install it, use this command:
npm install react@alpha react-dom@alpha
Step 3: Enable the new features (React Alpha/Domain Modes)
React 18 comes with several new features and improvements, such as the new streaming server renderer and automatic batching. However, these features are not enabled by default. To enable them, you need to add the following code to your index.js file:
import { unstable_createRoot } from ‘react-dom’;
unstable_createRoot(document.getElementById(‘root’)).render(<App />);
This code activates the new root API and makes use of its streaming server renderer while simultaneously enabling automatic batching to increase the performance of your app.
Step 4: Integrity Testing of Your Apps
Once you have upgraded to React 18 and enabled its new features, it’s essential that your app be tested thoroughly to make sure everything works as intended. Be sure to conduct this testing across a variety of browsers and devices so you can ensure it functions perfectly on all platforms.
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Conclusion
If you’re wondering whether upgrading to React 18 is worth your while, my answer would be an emphatic yes. Not only is React 18 an exciting major release but a game-changer too; its team has done tremendous work making its transition as seamless as possible. Migrate or upgrade existing apps over to React 18 to take advantage of all its features and functionalities within applications. Syndell’s React JS developers offer excellent assistance, so get a head start today by hiring them now to see how React 18 feels in practice before investing your own resources into learning its potential – hire React JS developers from Syndell now so you can put React 18 under your own control!
FAQs
React 17 introduced batching exclusively for browser events; with React 18, an upgraded version called Automatic Batching allows batching of all state updates from CreateRoot regardless of where they originated.
In React 17, each time the state of a component changes it would render multiple times; but with React 18, these updates can be combined and only one render will take place.
React has just received its stable version 18 release; many changes will benefit React developers such as Server Components, Suspense upgrades, or Concurrent Rendering; like any tool, it has its own set of advantages and disadvantages – perfect for certain tasks while subpar for others.
React Strict Mode is a developer tool used to identify potential bugs or issues in React applications’ codebase. It serves as feedback to developers when errors arise in an app’s code, without impacting its overall result. React Strict Mode does not render any visible user interface elements as part of its output, warning developers as appropriate and providing warnings accordingly.
React 18 introduced a concurrent rendering engine designed to optimize both front-end and server-side rendering, creating an efficient process for rendering both sides. Concurrent rendering also simplifies rendering processes on both platforms simultaneously.
React 18 introduces Automatic Batching, an enhanced form of batching. Automatic Batching supports state updates from createRoot no matter their source and enables automatic batching for all updates regardless of their origin.
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