Early this year, React 18 was launched with a number of noticeable improvements and fascinating new features! We always employ the most recent technology as a top react native developers.
React 18 offers a variety of freshly created hooks and features that make it as easy as possible to upgrade from earlier versions of React. Upgrading to React 18 ought to be simple and take no more than a minute. We’ll guide you through how to quickly update your apps to React 18 in this article.
Updating existing apps to React 18 is a rather straightforward process. Suspense as well as Transitions, amongst many other new features, will not operate adequately without React 18, despite the fact that the bulk of new features are created to be adopted quickly. You must update the project to React 18 in order to fully utilise the newest features.
React 17 can be updated to React 18 in what ways? The task can be finished in a single easy step. After opening your project, add this command.
npm install react react-dom
With this, your project would be updated to the latest version of React, in this instance it is React 18.0. If you’re using yarn, you have to enter this command
yarn add react react-dom
Installing React 18 only requires this! React 18 would now be installed automatically, enabling your project to be compatible with its new capabilities.
An error message showing reactDOM.render is no longer supported would be appearing once you install React 18. To resolve this issue, import create.Root from react-dom/client. This allowed you to unmount and establish a new root. Please be advised that if you ignore this step, your app will continue to function as if it were still running React 17. Upgrading to React 18 won’t affect your code if you do not even import the create.Root function!
You still need a few APIs for the applications to work with React 18 yet after deploying React 18. Some functions may perform differently in the newest edition as well. Let’s look at each one in isolation.
Client Rendering APIs
You still need a few APIs for the applications to work with React 18 yet after deploying React 18. Some functions may perform differently in the newest edition as well. Let’s look at each one in isolation.
// Before
import { render } from ‘react-dom’;
const container = document.getElementById(‘app’);
render(<App tab=”home” />, container);
// After
import { createRoot } from ‘react-dom/client’;
const container = document.getElementById(‘app’);
const root = createRoot(container); // createRoot(container!) if you use TypeScript
root.render(<App tab=”home” />);
unmountComponentAtNode is used in the place of by root.unmount in React 18
// Before
unmountComponentAtNode(container);
// After
root.unmount();
Before it was confirmed, it was believed that React 18’s brand-new suspense feature was to blame for the callback in the render’s problem. React 18 does away with the callback method in render because of this. There is presently no direct alternative for the render callback API.
// Before
const container = document.getElementById(‘app’);
render(<App tab=”home” />, container, () => {
console.log(‘rendered’);
});
// After
function AppWithCallbackAfterRender() {
useEffect(() => {
console.log(‘rendered’);
});
return <App tab=”home” />
}
const container = document.getElementById(‘app’);
const root = createRoot(container);
root.render(<AppWithCallbackAfterRender />);
The hydrate.root got swapped by ReactDOM.hydrate here. You would need to import hydrate.root in the latest version of React if your project needs hydration for server-side rendering.
// Before
import { hydrate } from ‘react-dom’;
const container = document.getElementById(‘app’);
hydrate(<App tab=”home” />, container);
// After
import { hydrateRoot } from ‘react-dom/client’;
const container = document.getElementById(‘app’);
const root = hydrateRoot(container, <App tab=”home” />);
// Unlike with createRoot, you don’t need a separate root.render() call here.
Strict Mode APIs
The <StrictMode> is stricter in React 18! It’s conceivable that a few of your applications won’t work once you transition them to React 18. In order to circumvent this problem, you would need to ascertain if the applications that don’t operate using React 18 have been wrapped with <StrictMode>. If they are, disabling Strict Mode while updating can enable React 18 compatibility for your old apps. Only after the transition to React 18 is ready, you can wrap the program, or a piece of it, once more in strict mode. That is, once the issues that were keeping your application from working have been resolved!
It is important to note that future revisions of React will increase the responsiveness to UI inputs. A development-only test has been added to the Strict Mode of React 18 to help discover any potential issues that might occur after putting these enhancements into practice. This functionality will automatically unmount and remount all components in the project as it is mounted for the initial session. The components would be remounted from their previous position during the second mount.
Server Rendering APIs
⦁ Every react-dom/server API was completely rewritten in React 18 to support simultaneously Streaming SSR as well as Suspense upon that server. The former Node streaming API was already discontinued due to this reason. This was implemented since the API did not support progressive Suspense server streaming. When utilizing the Node Streaming API, the following notice will now appear renderToNodeStream.
⦁ In order to stream in Node environments, we now need to utilize renderToPipeableStream.
⦁ In addition, a new API called renderToReadableStream is made accessible to make Suspense streaming possible on servers running Cloudflare and Deno.
⦁ Although they still work, the following APIs now only have limited functionality with suspense:
⦁ renderToString
⦁ renderToStaticMarkup
⦁ The renderToStaticNodeStream API will remain in use for email rendering.
New Library APIs
Taking library maintainers into consideration, additional APIs were implemented to React 18. These APIs would allow concurrent rendering, another key React 18 feature, to be used for certain purposes. Let’s have a quick discussion of these APIs.
⦁ Concurrent processes of external stores are made feasible by UseSyncExternalStore, allowing for concurrent modifications to the store.
⦁ CSS-in-JS libraries can correct technical issues brought on by injecting styles during rendering thanks to useInsertionEffect.
Automatic Batching APIs
Automatic Batching is a brand-new feature that has been added to React 18. When you activate automatic batching in the project, all you have to do is import create.root to tell React 18 to batch the code for you.
// After React 18 updates inside of timeouts, promises,
// native event handlers or any other event are batched.
function handleClick() {
setCount(c => c + 1);
setFlag(f => !f);
// React will only re-render once at the end (that’s batching!)
}
setTimeout(() => {
setCount(c => c + 1);
setFlag(f => !f);
// React will only re-render once at the end (that’s batching!)
}, 1000);
To avoid using automatic batching in your app, you can use flushSync.
import { flushSync } from ‘react-dom’;
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
}
Typescript Markup API
Typescript Markup API
If your project makes use of TypeScript, you have to make certain changes while upgrading to React 18. The most significant update in React 18 affects the @types/react or @types/react-dom dependencies. These are more effective in finding bugs and are generally safer.
The obligation to expressly list the child prop whenever listing another prop is the other key change. For illustration:
interface MyButtonProps {
color: string;
children?: React.ReactNode;
}
Setting Up Testing Environment
The alterations to the program that you must do to have React 18 to work with your current code have been covered in the prior sections. In this section, we’ll go over the modifications you ought to apply to the testing setup while using React 18.
The following issue may occur in your test console when you try to install your tests using create.root:
The current testing environment is not configured to support React 18
To get around this issue, you would have to set globalThis.IS REACT ACT ENVIRONMENT as true. This would let React know whether the application is being run in an environment akin to something like a unit test. If you set this setting to false, React would not mark warnings if an update is not wrapped in an act.
Note the Obsolete APIs
We just went over every outdated API for React 18, so let’s have a review by looking at the complete list of obsolete APIs in React 18. Please keep in mind to stop utilizing these APIs after you have upgraded to React 18. Your application will either run in React 17 else it won’t run at all if you use them.
⦁ react-dom: ReactDOM.render
⦁ react-dom: ReactDOM.hydrate
⦁ react-dom: ReactDOM.unmountComponentAtNode
⦁ react-dom: ReactDOM.renderSubtreeIntoContainer
⦁ react-dom/server: ReactDOMServer.renderToNodeStream
We are now finally set to use React 18!
The performance of apps developed using the latest version of the platform, React 18, has been improved by a number of new features that work in conjunction with one another. Upgrading to React 18 is really simple and therefore doesn’t require over a couple of seconds. To upgrade your existing apps to React 18 and then make use of all of its new capabilities, you would need to make some code changes. To make this procedure easier, React has introduced several new APIs that you can quickly incorporate into our software. This would enable our code to completely take advantage of React 18. Certain APIs are also discontinued as new APIs replace them. If you follow these steps, switching to React 18 would be simple.
Upgrade to React 18 now and have fun playing around with the new features!
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