React Version Upgrade

React is one of the most popular tools available for building user interfaces. From small personal projects to major enterprise programs, it’s utilised because of its reusable components and robust community support.

With each new release, React continues to evolve to stay modern and efficient. These modifications are meant to make programs easier to develop and maintain, as well as speedier.

In this Article, we’ll break down some key points about React 18, which include what’s new in React 18?, how it’s different from version 17?, why upgrading is worth it?, how you can upgrade?, and the problems that can be faced while upgrading.

Need for Upgrade

You may ask yourself, "Why bother upgrading?" if your project functions properly with React 17. Here's why React 18 is worthwhile, though:

• Offers Better Performance
  When UI updates are ready, React 18 can display them after preparing them in the background. Your app feels quicker and more responsive as a result.

• Provides a Smoother Experience
  Multiple re-renders occurred in React 17 as a result of adjustments made outside event handlers (such as inside setTimeout). React 18 boosts efficiency by batching them into a single update.

• Smarter State Management
  UseTransition and useDeferredValue are two hooks that make it easier to control loading and slow renderings.

• Future-Ready
  Future technologies such as React Server Components are built on top of React 18. By staying current today, you can avoid headaches later.

React 18 features compared to React version 17

Some of the major upgrades include concurrent rendering, a powerful enhancement that allows React to prepare multiple versions of the UI at the same time without blocking the main thread. This can be accessed by developers through the new startTransition API, which designates updates as non-urgent. For instance, it can wrap state updates for search results to maintain typing responsiveness even when processing intensive data.

Another major addition is automatic batching, which groups multiple state updates—even across asynchronous events—into a single render. React 18 also introduced new hooks like useTransition, which gives developers control over pending UI states (e.g., showing a loading spinner), and useId, which solves issues with generating consistent IDs between server and client renders. All of these are supported out of the box when using ReactDOM.createRoot instead of the older ReactDOM.render, unlocking these improvements with minimal changes.

Things to remember while upgrading

Upgrading from React 17 to 18 is simple and involves just two steps, but the major challenge lies with the peer dependencies & version error occurs. Before migrating your app to React 18 check these steps

Step 1 - Check Compatibility

• Verify that your current dependencies are prepared for React 18 before upgrading.
• To look for out-of-date packages, run “yarn outdated or npm outdated”.
• To verify React 18 support, check the official documentation for each library.
• Update any incompatible packages or look for safer substitutes.

Step 2 - Review and Refine Your code

• In React 18, several outdated React patterns won't function properly ( example. - react-spring@9.4.3 was not compatible with React 18, so I had to remove it ).
• Look out for deprecated lifecycle methods like componentWillMount, componentWillReceiveProps, and componentWillUpdate. These have functional alternatives now.
• Refactor to make advantage of functional components and hooks, which are React 18-friendly patterns.

Step 3 - Test Wisely and Carefully

• Establish a robust testing environment to identify problems early.
• Make use of end-to-end, integration, and unit tests.To ensure nothing breaks, run tests prior to, during, and following the upgrade.

Step-by-Step Migration Roadmap

Step 1 – Update Dependencies
Run in your project root:
npm install react@18 react-dom@18

Step 2 – Replace ReactDOM.render
Find where ReactDOM.render is called (usually index.js).
Migrate to reateRoot
Before (React 17)

import ReactDOM from ‘react-dom';
import App from './App';
ReactDOM.render(<App />, document.getElementById('root'));

After (React 18)

import { createRoot } from ‘react-dom/client';
import App from './App';
const root = createRoot(document.getElementById('root'));
root.render(<App />);

Step 3 – Run Codemons(optional)
This step fixes the deprecated APIs automatically
Terminal output –
npx react-codemod rename-unsafe-lifecycles
npx react-codemod update-react-imports

Step 4: Handle Breaking Changes
Check for legacy lifecycles methods and replace them

• componentWillMount → useEffect
• componentWillReceiveProps → getDerivedStateFromProps

Testing automatic batching by wrapping async state updates if needed

import { flushSync } from 'react-dom';
flushSync(() => {
  setState(newValue); // Forces immediate update
});

Step 5: Verify & Test
Run tests on your Terminal
npm test

Do Manual Checks

• Concurrent Mode: Test UI responsiveness (e.g., type in a search bar).
• SSR: Verify hydration errors.

Step 6: Optimize for React 18
Example: useTransition for slow renders

import { useTransition } from ‘react’;
function Search() {
  const [isPending, startTransition] = useTransition();
  const handleSearch = (query) => {
    startTransition(() => {
      setResults(fetchResults(query)); // Non-urgent update
    });
  }
  return (
    <>
      {isPending && <Spinner />}
      <input onChange={(e) => handleSearch(e.target.value)} />
    </>
  );
}

Step 7: Troubleshooting Tips
Issue – useEffect runs twice in development
Solution –

// Option 1: Make effect idempotent (safe to run multiple times)
// Option 2: Use for layout effects

import { useLayoutEffect } from 'react';
useLayoutEffect(() => { /* code */ }, []);

Issue – Third-party libraries break (e.g., react-spring)
Solution –
npm install react-spring@latest # Check for React 18 compatible versions

Reddit’s Comments

"React 18 has made useEffect fetching slightly worse… I had to switch to useLayoutEffect in places just to get the same experience."

"I love how React 18 makes apps feel smoother. useTransition is a game changer when dealing with slow data loads."

"Streaming SSR is 🔥. My site loads much faster now."
In short, the feedback is mixed: developers love the performance benefits but are cautious about ecosystem changes and subtle behavior shifts.

About React 19

React 19 is out, thankfully, it has been released with few breaking changes. Most of the core experience remains the same.

However, many libraries haven’t fully caught up yet. If you upgrade and something breaks, you might need to either: Downgrade temporarily
Or wait for library updates

New capabilities like Server Components and the React Compiler are exciting but haven’t been widely tested yet. Keep them out of long-term production apps for the time being.

Conclusion

More than just an update, React 18 represents a significant advancement towards a more rapid and adaptable React. It is worthwhile to upgrade your software if you are working on a new project or want to make sure it is future-proof.

Although there may be some hiccups along the way, the improvements in performance, the improved user experience, and the preparedness for upcoming advancements make the shift valuable.

If you’re spending too much time wiring up UI and state logic from scratch, DronaHQ gives you a faster way forward. With pre-built components, a visual builder, and AI to help scaffold React-style UIs instantly, you can skip the boilerplate and focus on delivering features. You’ll be shipping internal tools in hours, not weeks... Try it free or explore the component library to see what’s possible.

Be a part of the React 18 wave by starting small and properly testing!
Should I write about React version 19?

References -
https://react.dev/versions#react-18
https://www.geeksforgeeks.org/reactjs/how-to-upgrade-to-react-18/
https://www.reddit.com/r/reactjs/
https://react.dev/blog/2022/03/29/react-v18