React and Concurrent Mode

React and Concurrent Mode

React, the popular JavaScript library for building user interfaces, continues to evolve and adapt to the ever-changing web development landscape. As we end 2023, it's essential for developers to stay updated with the latest trends and advancements in React development. React's component-based architecture, Virtual DOM, declarative syntax, and extensive ecosystem make it a powerful and versatile tool for frontend development. Its simplicity, efficiency, and broad industry adoption have solidified its significance in modern web development. React continues to evolve, ensuring its relevance and usability for years to come.

Here’s a quick overview of the areas to be covered in this article:

  • Introduction to React 18
  • Explanation of what Concurrent Mode is
  • Benefits of using Concurrent Mode
  • Issues when using concurrent Mode in React
  • Conclusion

Now let's try to understand in detail what Concurrent Mode is in React.

Introduction to React 18

Building on the success of previous versions, React 18 brings substantial improvements and innovations. With enhancements to Concurrent Mode, automatic batching, event delegation, and the continued evolution of Server Components, React 18 offers a more responsive, efficient, and developer-friendly experience. This release reflects React's commitment to staying at the forefront of web development, empowering developers to create fast, dynamic, and user-friendly applications with ease .

Key features and improvements

Here are some key highlights and updates in React 18:

Concurrent Mode Enhancements : React 18 is advancing Concurrent Mode, which was introduced as a preview in previous versions. Concurrent Mode makes React more responsive by efficiently handling complex UI updates, allowing for smoother user experiences.

Automatic Batching : React 18 is introducing automatic batching of updates. This feature helps optimize performance by grouping multiple state updates into a single batch, reducing unnecessary renders and enhancing application efficiency.

Event Delegation : React 18 introduces event delegation, a technique that improves event handling efficiency by reducing the number of event listeners attached to the DOM. This can lead to performance improvements in applications with many interactive elements.

Server Components : Building on the Server Components preview introduced in React, React 18 further develops this feature. Server Components blur the lines between client and server rendering, potentially improving performance and simplifying the development of certain types of applications.

Improved DeveloperExperience : React 18 is enhancing the developer experience with new tools, debugging capabilities, and features that make it easier to create, test, and maintain React applications.

Smooth Transition : React 18 ensures a smooth transition for existing React applications. Developers can upgrade to React 18 without major disruptions to their existing codebase.

Community Feedback : React's development process often involves taking community feedback into account. Developers and users of React are encouraged to provide feedback and insights to shape the final release of React 18.1-

Concurrent Mode

Explanation of what Concurrent Mode is

React Concurrent Mode has been in the pipeline for some time now, and it's expected to make significant strides in 2023. This mode enhances the user experience by making apps more responsive and optimizing rendering. It allows React to work on multiple tasks simultaneously, making it a game-changer for complex applications. Here’s an example of the concurrent mode in React :


In the example above, we imported the unstable_ConcurrentMode as ConcurrentMode from the react package. We went ahead to wrap our component with the ConcurrentMode component. Doing this enables the Time Slicing algorithm to prioritize rendering based on importance. It is also important to note that unstable_ConcurrentMode is marked as unstable because it is still an experimental feature when writing this article and may likely change in future releases.

Benefits of using Concurrent Mode

Concurrent Mode in React offers several significant benefits for building more responsive and robust user interfaces in complex applications:

Improved Responsiveness : Concurrent Mode enables asynchronous rendering, allowing React to work on multiple tasks simultaneously. This leads to a more responsive user interface.

Prioritization : With Concurrent Mode, you can prioritize rendering updates based on their importance. This means that user interactions like clicks and keyboard input can be given higher priority, ensuring that the UI responds quickly to user actions.

Better Error Handling : Concurrent Mode enhances error boundaries, making it easier to capture and handle errors in your application. You can set up error boundaries at higher levels in the component tree to catch and gracefully handle errors, preventing the entire application from crashing due to a single error.

Looking at the issues or bad sides of using concurrent mode

Issues when using concurrent Mode in React

While Concurrent Mode in React offers many benefits, it also introduces some potential issues and challenges that developers should be aware of:

API Instability : With each future release, the API may change, making it a big challenge to use in production environments as this may call for code refactoring and upgrade to keep up with the latest trend.

Learning Curve : Concurrent Mode introduces new concepts and patterns, such as Suspense, time slicing, and asynchronous rendering. Developers may need time to learn and adapt to these new concepts, which can be challenging, especially for those familiar with traditional React.

Error Handling : While Concurrent Mode enhances error boundaries, it also requires developers to adapt their error-handling strategies. Suspended components and the potential for asynchronous rendering can lead to different error scenarios that need to be handled correctly.


In conclusion, the evolution of React has been marked by a relentless pursuit of better performance and user experience. With the introduction of React 18, a new chapter has begun, bringing forth the innovative concept of Concurrent Mode.

Concurrent Mode represents a significant leap forward in React's capabilities, offering developers the tools to create more responsive and resilient user interfaces. It's a paradigm shift that allows React applications to handle complex rendering tasks with grace and efficiency.

2023-11-22 | 5 min read
Share article

More articles