React
React is a powerful JavaScript library for building interactive user interfaces efficiently, using a component-based approach, a virtual DOM and reactive state management.
React is a modern open-source library for building user interfaces, developed by Meta (Facebook). It is designed primarily for web and mobile applications where responsiveness and dynamic interface behavior are essential. React lets developers build applications from small, isolated components that update automatically when the data changes, which simplifies the code structure and makes it more reusable.
Component model, virtual DOM and reactivity
The basic building block in React is the component – a function or class that returns a description of what the user interface should look like. This description is usually written with JSX (JavaScript XML), a syntax extension that looks like HTML but is fully compatible with JavaScript. Components can have their own state and accept input parameters (props), which makes it easy to create interactive and dynamic interfaces.
React does not rewrite the page content directly on every change; instead it uses the so-called virtual DOM – an internal in-memory representation of the real DOM tree. When the data changes, React first computes the differences (diffing) between the previous and the new virtual state and then applies the most efficient updates possible to the real DOM. This approach significantly improves performance, especially for complex and frequently changing interfaces.
Application state management also plays an important role. React lets you manage local state in individual components using hooks (e.g. useState, useEffect), and thanks to its openness you can also use external tools such as Redux, Zustand or Recoil for global management of more complex data structures. For better readability, stability and catching errors while writing code, React is often used together with TypeScript, which extends JavaScript with static typing. This makes development much easier in larger teams and on long-term projects.
Thanks to its clarity, extensive documentation and large community, React has become the dominant technology in the frontend world. It is the foundation for many other frameworks and libraries, including Next.js, Gatsby and React Native, and companies around the world use it to build maintainable, interactive and high-performance user interfaces.
Links to official resources