Best React Course

Props (short for properties) are read-only inputs passed to components. They allow data flow from parent to child components.

State is a built-in object used to store data that changes over time. It determines how the component behaves and renders.

React JS is a powerful JavaScript library used for building dynamic and responsive user interfaces. At TOPS Technologies, you’ll learn React from industry experts through real-time projects, practical sessions, and hands-on training, making you job-ready in the competitive IT market.

React is a JavaScript library developed by Facebook for building user interfaces, especially single-page applications. It uses a component-based architecture and efficiently updates the user interface using a virtual DOM.

Key features include JSX syntax, component-based structure, virtual DOM, one-way data binding, reusable components, and support for hooks for functional programming.

JSX (JavaScript XML) is a syntax extension that allows writing HTML-like code in JavaScript. It makes the structure of UI components more readable and intuitive.

The virtual DOM is an in-memory representation of the real DOM. React compares the virtual DOM with a snapshot (diffing) and updates only the changed elements, improving performance.

  The real DOM updates the entire tree, which is slow. The virtual DOM updates only the changed parts, making rendering more efficient and faster.

Components are reusable, independent pieces of UI that return JSX. There are two types: Functional Components and Class Components.

React JS offers several powerful features that simplify and enhance the development of modern applications:

• JSX (JavaScript XML): A syntactic extension that allows developers to write HTML-like code within JavaScript, improving code readability
• Virtual DOM: React maintains a virtual representation of the real DOM to optimize updates and rendering processes.
• Component-Based Architecture: Applications are divided into small, reusable, and independent pieces called components, making the code modular and maintainable.
• Unidirectional Data Flow: Data flows in one direction, from parent to child through props, ensuring predictable and easy-to-debug application behavior.
• Declarative UI: Developers describe what the UI should look like, and React handles the rendering and updates efficiently.

The Virtual DOM is a lightweight, in-memory representation of the actual Document Object Model (DOM). When a component’s state or props change, React updates the Virtual DOM first. It then compares this new version with the previous one using a process called “diffing.” After identifying the minimal number of changes needed, React updates only those parts of the real DOM. This selective update mechanism makes React highly performant and responsive.

JSX stands for JavaScript XML and is a syntax extension for JavaScript commonly used with React. It allows developers to write HTML-like code within JavaScript files, which makes it easier to visualize the UI structure. JSX is not understood by browsers directly; it is transpiled into standard JavaScript using tools like Babel. JSX improves development efficiency by combining markup and logic in a single component file.

A component in React is a fundamental building block used to create user interfaces. Components are JavaScript functions or classes that return React elements describing what should appear on the screen. There are two types of components:

• Functional Components: Simple JavaScript functions that return JSX.
• Class Components: ES6 classes that extend from React.Component and include lifecycle methods.
  Components can manage their own state and can be reused across the application to ensure consistency and modular development.

• Functional Components are basic JavaScript functions that take props as input and return JSX. With the introduction of React Hooks, functional components can now manage state and side effects, making them just as powerful as class components.
• Class Components are based on ES6 classes and offer built-in lifecycle methods like componentDidMount, shouldComponentUpdate, etc., to manage component behavior.
• React now encourages the use of functional components due to their simplicity, improved performance, and cleaner syntax, especially when combined with hooks.

React Hooks are special functions introduced in React 16.8 that allow developers to use state and other React features in functional components. Before hooks, only class components could manage state or access lifecycle methods. With hooks, functional components became more powerful and concise. Commonly used hooks include:

• useState – for managing local state
• useEffect – for handling side effects
• useContext – for accessing global context
• useRef, useReducer, and others for advanced logic

Hooks simplify the code and encourage reusability and separation of concerns.

The useState hook is used in functional components to create and manage local state. It returns an array containing the current state value and a function to update it. This hook allows components to be interactive and dynamic. For example, clicking a button can change the state and re-render the UI with the new data. It enables functional components to store user input, toggle values, or track counters without needing a class.

The useEffect hook allows you to perform side effects in your React components, such as fetching data from APIs, updating the DOM, or setting up subscriptions. It runs after the component has rendered and can be controlled using a dependency array to decide when the effect should re-run. For example, passing an empty array runs the effect only once (like componentDidMount). useEffect helps manage lifecycle-related logic within functional components.

Props (short for properties) are inputs passed from a parent component to a child component. They are read-only and help make components reusable and dynamic. Props allow data to flow in one direction, ensuring a predictable UI. For example, a parent can send a name, color, or event handler to a child component through props. Inside the child, props are accessed to display content or trigger actions based on the parent’s data.