React.Js Introduction

React.Js Introduction


Lesson 21: Introduction to React



Introduce React.js as a frontend library for building user interfaces.


React.js revolutionized frontend development by introducing a component-based approach. Let's explore its core concepts:


 Overview of React.js and its advantages

- React.js: A JavaScript library for building interactive user interfaces, developed by Facebook.

- Advantages: Offers a virtual DOM for efficient rendering, reusable components, and a declarative programming style.


 Virtual DOM and component-based architecture

- Virtual DOM: Represents a lightweight copy of the actual DOM, enabling efficient updates and minimizing direct manipulations to the real DOM.

- Component-based architecture: Encourages building UIs as a composition of reusable and encapsulated components.


 React ecosystem and tooling

- React ecosystem: Comprises additional libraries (Redux for state management, React Router for routing, etc.) enriching React's capabilities.

- Tooling: Tools like Create React App, Babel, Webpack simplify project setup and development workflows.

 Lesson 22: React Sample App & Project Structure



Set up a basic React application and understand its structure.


 Creating a sample project in React

- Setup: Use tools like Create React App or manually configure a React project with necessary dependencies.

- Starting point: Create a simple application with components and basic functionalities.


 Component hierarchy and project organization

- Component hierarchy: Organize components in a tree-like structure, defining parent-child relationships.

- Project organization: Maintain a structured folder layout for components, assets, styles, and other resources.


 Configuring React with Babel and Webpack

- Babel: Transpiles modern JavaScript code (ES6+) into a format compatible with older browsers.

- Webpack: Bundles and optimizes project files, allowing the use of different file types (JSX, CSS, etc.) within React projects.

 Lesson 23: Components



Dive deeper into React components and their usage.


 Class components vs functional components

- Class components: Traditional React components created using ES6 classes, managing state and utilizing lifecycle methods.

- Functional components: Introduced with React hooks, simpler, and used for UI rendering without managing state.


 Props and state in React

- Props: Data passed from parent to child components, allowing components to be dynamic and reusable.

- State: Internal data management within components, influencing component behavior and rendering.


 Lifecycle methods of React components

- Lifecycle methods: Functions executed at different stages of a component's life (mounting, updating, unmounting), facilitating side effects and interactions with the DOM.

- Example:


  class ExampleComponent extends React.Component {

    componentDidMount() {

      // Executes after component is mounted to the DOM

      // Ideal for AJAX requests or subscriptions


    componentDidUpdate() {

      // Executes after component updates

      // Useful for responding to prop or state changes



    componentWillUnmount() {

      // Executes before component is unmounted and destroyed

      // Clean-up activities or removing subscriptions




 Lesson 24: JSX & Props



Explore JSX syntax and understand the usage of props in React.


 JSX syntax and its advantages

- JSX: Extension to JavaScript that allows writing HTML-like code within JavaScript, facilitating component rendering.

- Advantages: Simplifies UI development by combining HTML structure with JavaScript logic.


 Passing data between components using props

- Props passing: Mechanism to pass data from parent components to child components.

- Example:


  const ParentComponent = () => {

    const message = 'Hello from Parent!';

    return <ChildComponent message={message} />;



  const ChildComponent = (props) => {

    return <p>{props.message}</p>;



 Best practices for using JSX and props effectively

- Consistent naming: Maintain a consistent naming convention for props to enhance code readability.

- Avoid mutating props: Props should be treated as read-only to maintain the unidirectional flow of data.


Understanding React's component-based structure, state management, and JSX syntax forms the foundation for building interactive and dynamic user interfaces efficiently. These principles empower developers to create scalable and maintainable frontend applications in React.js.