What’s new in React?

React is a continuously evolving library in the ever-changing web development landscape. As you embark on your journey to learn and master React, it’s important to understand the evolution of the library and its updates over time.

One of the advantages of React is that its core API has remained relatively stable in recent years. This provides a sense of continuity and allows developers to leverage their knowledge from previous versions. The conceptual foundation of React has remained intact, meaning that the skills acquired three or five years ago can still be applied today. Let’s take a step back and trace the history of React from its early versions to the recent ones. From React 0.x to React 18, numerous pivotal changes and enhancements have been made as follows:

• React 0.14: In this version, the introduction of functional components allowed developers to utilize functions as components, simplifying the creation of basic UI elements. At that time, no one knew that now we would write only functional components and almost completely abandon class-based components.
• React 15: With a new versioning scheme, the next update of React 15 brought a complete overhaul of the internal architecture, resulting in improved performance and stability.
• React 16: This version, however, stands as one of the most notable releases in React’s history. It introduced hooks, a revolutionary concept that enables developers to use state and other React features without the need for class components. Hooks make code simpler and more readable, transforming the way developers write components. We will explore a lot of hooks in this book. Additionally, React 16 introduced Fiber, a new reconciliation mechanism that significantly improved performance, especially when dealing with animations and complex UI structures.
• React 17: This version focused on updating and maintaining compatibility with previous versions. It introduced a new JSX transform system.
• React 18: This release continues the trajectory of improvement and emphasizes performance enhancements and additional features, such as the automatic batching of renders, state transitions, server components, and streaming server-side rendering. Most of the important updates related to performance will be explored in Chapter 12, High-Performance State Updates. More details about server rendering will be covered in Chapter 14, Server Rendering and Static Site Generation with React Frameworks.
• React 19: Introduces several major features and improvements. The React Compiler is a new compiler that enables automatic memoization and optimizes re-rendering, eliminating the need for manual useMemo, useCallback, and memo optimizations. Enhanced Hooks like use(promise) for data fetching, useFormStatus() and useFormState() for form handling, and useOptimistic() for optimistic UI simplify common tasks. React 19 also brings simplified APIs, such as ref becoming a regular prop, React.lazy being replaced, and Context.Provider becoming just Context. Asynchronous rendering allows fetching data asynchronously during rendering without blocking the UI, while error handling improvements provide better mechanisms to diagnose and fix issues in applications.

React’s stability and compatibility make it a reliable library for long-term use, while the continuous updates ensure that it remains at the forefront of web and mobile development. Throughout this book, all examples will utilize the latest React API, ensuring that they remain functional and relevant in future versions.

Now that we have explored the evolution and updates in React, we can delve deeper into React and examine how to get set up with the new React project.