Abstract
The article provides a comprehensive analysis of the use of the React library in the creation of interactive user interface elements within modern web applications. The focus is placed on the architectural logic of React as a foundational framework for building stable, scalable, and predictable interface solutions. Interactivity is interpreted not as a set of isolated visual effects but as a systemic property of the interface, determined by the relationship between state management, component structure, and the event-handling model. The paper consistently examines the principles of declarative interface description, component-based architecture, and unidirectional data flow, which define the specific features of designing interactive elements in React. Particular attention is given to the role of state as the central mechanism governing interface behavior, as well as to the distinction between local and global state in the context of complex user interaction scenarios. The significance of the virtual representation of the interface is analyzed as a means of optimizing updates and maintaining visual consistency under conditions of frequent data changes. The article demonstrates that the use of a virtual DOM makes it possible to reduce direct manipulations of the actual document structure, which is critically important for the performance and stability of interactive interfaces. The event model implemented in React is examined as a formalized mechanism linking user actions to state transitions, ensuring deterministic and reproducible behavior of interface components. A comparative analysis highlights the differences between the React approach and traditional imperative models of user interface development, allowing for a systematic justification of its architectural advantages in the design of complex interface systems. The study concludes that React should be regarded not merely as a practical development tool, but as a methodological foundation for designing interactive user interfaces oriented toward logical consistency, controllability, and long-term architectural sustainability of software solutions.