React: Features, Components, Hooks, and Routing Essentials

What are the core features that define React?

React is defined by fundamental features that streamline UI development and enhance performance. Its declarative nature simplifies code, while the Virtual DOM ensures efficient updates by minimizing direct DOM manipulation. The library promotes modularity through its Component-Based Architecture, allowing for the creation of reusable, isolated UI pieces with a predictable Unidirectional Data Flow.

• Component-Based Architecture
• JSX
• Virtual DOM
• Unidirectional Data Flow
• Declarative UI

How are JSX and dynamic variables used in React development?

JSX, or JavaScript XML, is a syntax extension allowing developers to write HTML structures directly within JavaScript code, enhancing readability. Dynamic variables are crucial within JSX for injecting data and expressions into the rendered output. This combination enables the creation of dynamic content where data changes automatically reflect in the user interface, bridging the gap between logic and presentation layers.

• JSX
• Variables

What are the different types of components in React and how do they manage data?

Components are the building blocks of any React application, responsible for rendering UI elements. Functional Components are simple JavaScript functions managing state using Hooks like useState. Class Components rely on class structures and lifecycle methods. Both types use Props to receive external data from parent components, ensuring clear data flow and modularity.

• Functional Components
• Class Components

What types of applications can be built using React?

React is highly versatile, suitable for building a wide range of modern web applications, from simple interactive tools to complex enterprise systems. Common introductory projects demonstrate core concepts like state management and data display. These applications often involve managing user input, displaying structured data, and handling visual themes, providing practical experience with React's core capabilities.

• Counter App
• TODO App
• Table
• Theme

How is conditional rendering implemented in React?

Conditional rendering displays different elements or components based on the current application state or props. Developers use JavaScript expressions within JSX to achieve this. Techniques like the ternary operator provide concise inline logic, while short-circuit evaluation is ideal for rendering elements only when a specific condition evaluates to true, ensuring dynamic UI presentation.

What is the difference between State and Props in React?

State and Props are fundamental concepts for managing data. State is internal data managed by a component that can change over time, triggering re-renders. Props are external, read-only data passed down from a parent component. Together, they facilitate the Unidirectional Data Flow, ensuring that data moves predictably through the application hierarchy and maintaining component isolation.

How do components manage their lifecycle in React?

The component lifecycle tracks events from creation to destruction. While Class Components used specific lifecycle methods, modern React uses Functional Components where the lifecycle is managed through Hooks. The useEffect hook handles mounting, updating, and unmounting logic in a unified and functional manner, simplifying complex component behavior management.

• Class component lifecycle
• Functional components lifecycle

How are side effects and cleanup handled in functional components?

Side effects, such as data fetching or subscriptions, occur outside the normal React rendering process. In functional components, these are managed using the useEffect hook, which runs after rendering. The hook supports a crucial cleanup function that executes before the component unmounts or before the effect runs again, preventing memory leaks and ensuring resource management.

• useEffect hook

How is navigation and routing managed in a React application?

Routing is essential for building multi-page experiences within a single-page application (SPA), typically managed by external libraries like React Router. This system allows users to navigate between different views without full page reloads. It supports defining various route types, handling URL parameters, and implementing navigation controls, ensuring a seamless user experience across application sections.

• Simple routes
• Protected Routes
• Private Routes
• Error page 404
• setup & linking routes
• url & query params
• Navigation

What are the methods for handling forms in React?

Handling user input through forms is achieved using controlled or uncontrolled components. Controlled forms manage input values using React state, enabling real-time validation. Uncontrolled forms rely on the DOM, often using the useRef hook to access values upon submission. Both methods require careful handling of multiple fields and submission logic for effective data capture.

• Controlled form using useState
• Uncontrolled forms using useRef
• Handling Multiple fields and Submit

How does React Context simplify state management?

React Context provides a mechanism to share data globally across a component tree without prop drilling, suitable for medium-scale state management like themes or user authentication. For larger, more complex applications requiring predictable state transitions and advanced debugging, external libraries such as Redux are often utilized alongside the Context API.

• Context Api
• Redux

Why are Custom Hooks beneficial in React development?

Custom Hooks are reusable JavaScript functions that extract component logic, such as stateful behavior or side effects, into modular units. They promote significant code reuse across different components, improve code readability, and help separate concerns. This modular approach makes complex logic easier to test, maintain, and scale throughout the application lifecycle.

How is error handling managed in React applications?

Effective error handling is crucial for application stability and user experience. React applications typically manage runtime errors using Error Boundaries, which are specialized components designed to catch JavaScript errors in their child tree. This mechanism prevents the entire application from crashing and allows developers to display a graceful fallback UI instead of a broken interface.

Which Hooks are used for performance optimization in React?

React offers several Hooks to prevent unnecessary re-renders and boost performance. React.memo memoizes functional components, while useCallback memoizes functions, and useMemo memoizes expensive calculation results. Additionally, react.lazy combined with Suspense enables efficient code splitting and lazy loading of components, optimizing initial load times.

• React.memo
• useCallback
• useMemo
• react.lazy with Suspense UI

What are the steps for building and deploying a React application?

Preparing a React application for production involves creating an optimized build that is highly compressed and ready for deployment. The production build bundles all assets, minimizes code, and optimizes performance. Once built, the application is deployed to hosting platforms like Vercel or Netlify, which offer streamlined continuous deployment pipelines for efficient scaling.

• Production Build
• Deployment using Vercel or Netlify

What is the purpose of a new node in the application structure?

In the context of a React application structure, a 'new node' typically serves as a placeholder for a future component, feature, or structural element yet to be fully defined. It signifies an area of planned expansion or a modular unit that will eventually house specific logic, state, or UI elements, maintaining the overall component hierarchy and modular design.

Which essential Hooks are available for managing state and effects?

Hooks are functions that allow functional components to access React state and lifecycle features. Essential Hooks include useState for managing local state and useEffect for handling side effects. Specialized Hooks like useReducer, useContext, and optimization Hooks provide advanced capabilities for complex state management, performance tuning, and accessing context data efficiently.

• useState
• useEffect
• useReducer
• useLayoutEffect
• useMemo
• React.memo
• useCallback
• useRef
• useContext