React JS

Introducing React JS

What is React JS?

React JS, often simply referred to as React, is a JavaScript library for building user interfaces, especially single-page applications where you need a fast, interactive user experience. Developed by Facebook, it allows developers to create reusable UI components and manage the state of these components efficiently. React uses a virtual DOM to improve performance and facilitate a smoother user experience.

What is a Scripting Language?

A scripting language is a type of programming language designed for integrating and communicating with other programming languages. They are usually used to automate tasks that would otherwise be executed manually or to develop applications that interact with other systems.

Advantages of Scripting Languages

Ease of Use: Scripting languages often have simpler syntax compared to compiled languages, making them easier to learn and use.
Flexibility: They allow quick changes and updates to scripts without needing a full recompilation.
Productivity: They enable rapid development and testing of code, enhancing productivity.
Integration: They can easily interact with other software systems and languages.

Scripting Language Category

Server-Side Scripting Languages

Examples: PHP, Python, Ruby, Node.js
Purpose: Execute on the server to generate dynamic web content and handle server-side logic.

Client-Side Scripting Languages

Examples: JavaScript, TypeScript
Purpose: Execute in the user's browser to create interactive web pages and manage client-side operations.

Scripting vs Programming

Scripting: Typically used for automating tasks and often interpreted at runtime (e.g., JavaScript, Python). They are usually embedded in other software or used to control other applications.
Programming: Encompasses creating standalone applications with more complex structures and functionalities (e.g., C++, Java). It involves both compiling and interpreting code and usually includes building complex systems from scratch.

What is JavaScript?

JavaScript is a high-level, interpreted scripting language primarily used to create and control dynamic content on websites. It allows developers to implement complex features such as interactive forms, animations, and real-time updates.

What is JavaScript Used For?

Client-Side Web Development: Enhancing user interactions and handling events within a web browser.
Server-Side Development: Using environments like Node.js to build scalable network applications.
Game Development: Creating interactive and engaging games.
Mobile Apps: Using frameworks like React Native to build cross-platform mobile applications.

What is a JavaScript Library?

A JavaScript library is a collection of pre-written JavaScript code that simplifies the development of common tasks. Libraries offer ready-to-use functions and methods to make coding more efficient and modular. For example, jQuery is a popular JavaScript library that simplifies DOM manipulation and event handling.

What is the Difference Between a JavaScript Library and a Framework?

JavaScript Library: A library provides specific functions and methods that you can use to accomplish particular tasks. You call the library's code when needed (e.g., jQuery).
Framework: A framework provides a more comprehensive structure and set of conventions for building applications. It often dictates the architecture and flow of your application, and you work within its guidelines (e.g., Angular).

React JS vs Angular

React JS:

Type: Library focused on building UI components.
Data Binding: One-way data binding.
Learning Curve: Generally easier to learn due to its focus on view layer only.
Flexibility: Provides more flexibility, allowing developers to choose their tools and libraries.

Angular:

Type: Framework providing a complete solution for front-end development.
Data Binding: Two-way data binding.
Learning Curve: Steeper due to its comprehensive set of features and concepts.
Opinionated: More opinionated, providing a specific way to structure and build applications.

Why React?

React offers a component-based architecture that makes building complex UIs more manageable. Its virtual DOM enhances performance by minimizing direct manipulation of the real DOM, and its unidirectional data flow helps in maintaining consistency.

Advantages of React JS | Features of React

Component-Based Architecture: Encourages reusable code and modular design.
Virtual DOM: Improves performance by updating only parts of the DOM that have changed.
One-Way Data Binding: Ensures that data flows in a single direction, making the code more predictable.
Rich Ecosystem: A robust ecosystem with tools like React Router and Redux for state management.

Disadvantages of React JS | Limitations of React

Learning Curve: While the core library is straightforward, the ecosystem and additional tools can be overwhelming.
Boilerplate Code: Sometimes requires a significant amount of boilerplate code, especially when integrating with other libraries.
SEO Challenges: React’s client-side rendering can pose challenges for search engine optimization, though this can be mitigated with server-side rendering solutions.

Where to Use React JS

React is ideal for building dynamic and interactive user interfaces, particularly for single-page applications (SPAs) where efficient updates and a responsive user experience are critical. It is also used for building mobile applications using React Native.

What is a Single Page Application (SPA)?

A Single Page Application (SPA) is a type of web application that interacts with the user by dynamically rewriting the current page rather than loading entire new pages from the server. This approach provides a smoother, more responsive user experience similar to a desktop application.

Summary

React JS is a powerful JavaScript library for building dynamic user interfaces, particularly suited for single-page applications. Unlike full frameworks like Angular, React focuses on the view layer and provides a component-based architecture that enhances performance and code maintainability. JavaScript, the core language React is built on, is widely used for both client-side and server-side development. Understanding the distinction between libraries and frameworks, as well as the specific advantages and limitations of React, helps developers make informed decisions about when and how to use this tool effectively.

Setup Environment for React JS

Setting up a React JS development environment involves configuring various tools and utilities to create and manage React applications efficiently. Below is a step-by-step guide on setting up a React JS project, including using CDN links and setting up a local development environment.

1. How to Setup React JS Project Using CDN Links

Using CDN Links is a quick way to start experimenting with React without installing any additional tools. This method is suitable for learning and small projects but is less practical for larger, production-ready applications.

Steps:

Create an HTML File: Create a new HTML file (e.g., index.html) and add the following code:

Html

<!DOCTYPE html>

<head>

<title>React with CDN</title>

</head>

<body>

const App = () => {

return <h1>Hello, React with CDN!</h1>;

};

ReactDOM.render(<App />, document.getElementById('root'));

</script>

</body>

</html>

Open in Browser: Open the HTML file in a web browser, and you should see "Hello, React with CDN!" rendered on the page.

2. Basic Requirements to Set Up Development Environment

To create and manage React applications efficiently in a professional development environment, you will need several tools.

Text Editor/Source Code Editor

Visual Studio Code (VS Code): A popular and versatile text editor with features like syntax highlighting, IntelliSense, and integrated terminal.

Download & Install: Visual Studio Code

Web Browser

Recommended Browsers: Chrome, Firefox, Edge, or any modern browser.

Recommended Extension: React Developer Tools for inspecting React components.

React Developer Tool

Purpose: Helps in debugging React applications by providing an interface to inspect React component hierarchy and state.

Installation:

Chrome: Install the React Developer Tools extension from the Chrome Web Store.
Firefox: Install the React Developer Tools extension from Firefox Add-ons.

NPM (Node Package Manager)

Purpose: Manages JavaScript packages and dependencies for React and other libraries.

Installation: Comes with Node.js. Download and install Node.js, which includes npm.

Webpack

Purpose: A module bundler that helps in bundling JavaScript files and other assets (like CSS and images) for deployment.

Installation: Install Webpack locally in your project using npm.

Bash

npm install --save-dev webpack webpack-cli

Babel

Purpose: Transpiles modern JavaScript (including JSX used in React) into a version compatible with older browsers.

Installation: Install Babel along with its presets and plugins.

Bash

npm install --save-dev @babel/core @babel/cli @babel/preset-env @babel/preset-react

3. Complete Visual Studio Code Setup

1. Install VS Code Extensions:

ESLint: Linting tool for maintaining code quality.
Prettier: Code formatter to ensure consistent code style.
Reactjs code snippets: Provides useful code snippets for React development.
Bracket Pair Colorizer: Helps in visualizing matching brackets.

2. Configure VS Code:

Settings: Configure settings like formatting on save, linting rules, and snippet preferences in your workspace settings or user settings.

Example Configuration (settings.json):

Json

{

"editor.formatOnSave": true,

"eslint.validate": ["javascript", "javascriptreact"],

"prettier.singleQuote": true,

"javascript.format.enable": false

}

4. Complete NPM Setup

1. Initialize a New React Project: Use Create React App (CRA) to set up a new React project with a single command.

Bash

npx create-react-app my-app

cd my-app

npm start

2. Project Structure:

public/: Contains static files like index.html.
src/: Contains React components, styles, and other JavaScript files.
package.json: Manages project dependencies and scripts.

5. How to Install React Developer Tool

1. Chrome:

Open Chrome and navigate to the React Developer Tools extension page.
Click "Add to Chrome" and follow the prompts.

2. Firefox:

Open Firefox and go to the React Developer Tools add-ons page.
Click "Add to Firefox" and follow the prompts.

Using the Tool:

After installation, you can access the React DevTools in the browser’s developer tools panel. This provides a new "Components" and "Profiler" tab for inspecting and profiling React components.

Summary

Setting up a React development environment involves choosing the right tools and configuring them appropriately. For a quick start, you can use CDN links to include React in your HTML files. For a more robust setup, you’ll need a text editor like Visual Studio Code, a web browser with React Developer Tools, npm for managing dependencies, and tools like Webpack and Babel for bundling and transpiling code. Using Create React App simplifies the initial setup, and installing necessary VS Code extensions and configuring npm enhances the development experience.

Setup/Create React JS Project

Creating a React JS project involves setting up the environment and understanding how React manages its components and state. Below is a comprehensive guide to setting up and understanding React projects.

1. How to Setup/Create React JS Project Using NPM

Using the create-react-app Command

create-react-app is a command-line tool that sets up a new React project with a preconfigured build setup. It simplifies the initial setup by handling the configuration of Webpack, Babel, and other development tools.

Steps:

Install Node.js and npm: Ensure you have Node.js and npm installed. You can download and install them from nodejs.org.
Create a New React Project: Open your terminal or command prompt and run:

Bash

npx create-react-app my-app

Replace my-app with your desired project name.

Navigate to Project Directory:

Bash

cd my-app

Start the Development Server:

Bash

npm start

This will start the development server and open your new React app in the default web browser.

Using the NPM Command (Using Webpack and Babel)

If you want to set up React manually using Webpack and Babel, you need to configure these tools yourself. This method offers more control over the setup but requires more configuration.

Steps:

Create a New Directory:

Bash

mkdir my-app

cd my-app

Initialize npm:

Bash

npm init -y

Install React and ReactDOM:

Bash

npm install react react-dom

Install Webpack and Babel:

Bash

npm install --save-dev webpack webpack-cli webpack-dev-server babel-loader @babel/core @babel/preset-env @babel/preset-react html-webpack-plugin

Create Configuration Files:

webpack.config.js:

const path = require('path');

const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {

entry: './src/index.js',

output: {

filename: 'bundle.js',

path: path.resolve(__dirname, 'dist'),

module: {

rules: [

{

test: /\.(js|jsx)$/,

use: {

loader: 'babel-loader',

options: {

presets: ['@babel/preset-env', '@babel/preset-react'],

resolve: {

extensions: ['.js', '.jsx'],

plugins: [

new HtmlWebpackPlugin({

}),

devServer: {

contentBase: path.join(__dirname, 'dist'),

compress: true,

port: 3000,

};

.babelrc:

Json

{

"presets": ["@babel/preset-env", "@babel/preset-react"]

}

Create Project Structure:

/src/index.js:

import React from 'react';

import ReactDOM from 'react-dom';

import App from './App';

ReactDOM.render(<App />, document.getElementById('root'));

/src/App.js:

import React from 'react';

const App = () => {

return <h1>Hello, React with Webpack and Babel!</h1>;

};

export default App;

/public/index.html:

Html

<!DOCTYPE html>

<head>

<title>React App</title>

</head>

<body>

</body>

</html>

Start the Development Server:

Bash

npx webpack serve

2. React JS Folder Structure

Typical folder structure:

public/: Contains static files like index.html.
src/: Contains all source code files.

index.js: Entry point for the React application.
App.js: Main component for the application.
components/: Folder for React components.
styles/: Folder for CSS or style files.

3. DOM vs Virtual DOM

DOM (Document Object Model): Represents the structure of the HTML document as a tree of objects. Every change in the UI directly manipulates the DOM, which can be slow if the changes are frequent or complex.
Virtual DOM: A lightweight in-memory representation of the actual DOM. React maintains a virtual DOM to optimize performance by minimizing direct interactions with the actual DOM.

4. How is Virtual DOM Faster?

The Virtual DOM improves performance by:

Batching Updates: React batches multiple updates to the virtual DOM and applies them in a single operation.
Efficient Diffing Algorithm: React compares the current virtual DOM with the previous one using a diffing algorithm to determine the minimal set of changes required.
Selective Updates: Only updates the parts of the real DOM that have changed, rather than re-rendering the entire DOM.

5. How Does React Use Virtual DOM?

React uses the Virtual DOM as follows:

Render Method: When a component’s state or props change, React creates a new Virtual DOM tree.
Diffing: React compares the new Virtual DOM tree with the previous one to determine changes.
Reconciliation: React applies the necessary changes to the actual DOM based on the diffing results, ensuring efficient updates.

6. Strict Mode in React JS

Purpose: React’s StrictMode is a development tool that helps identify potential problems in an application. It activates additional checks and warnings for its descendants.

Usage:

import React from 'react';

import ReactDOM from 'react-dom';

import App from './App';

ReactDOM.render(

<React.StrictMode>

<App />

</React.StrictMode>,

document.getElementById('root')

);

Benefits:

Identifies components with unsafe lifecycle methods.
Warns about deprecated APIs.
Helps detect unexpected side effects.

7. Extends and Implements in React JS

Extends: In React, components typically extend React.Component to create class components. This allows the component to inherit methods and properties from React.Component.

class MyComponent extends React.Component {

render() {

return <div>Hello, World!</div>;

}

Implements: React components don’t use interfaces in the same way as other languages like TypeScript or Java. Instead, React components are either class-based or functional.

8. render() Methods

Class Components: The render() method is required in class components and returns the JSX to be displayed.

class MyComponent extends React.Component {

render() {

return <div>Hello, World!</div>;

}

Functional Components: Don’t require a render() method. The function itself returns the JSX.

Copy code

const MyComponent = () => <div>Hello, World!</div>;

9. React Elements

Definition: React elements are the smallest building blocks of React apps. They describe what should appear on the screen. Elements are immutable and can be created using React.createElement() or JSX.

createElement() Method:

const element = React.createElement('h1', null, 'Hello, World!');

10. ReactDOM.render() Method

Purpose: The ReactDOM.render() method is used to render a React element or component into a specified DOM container.

Example:

import React from 'react';

import ReactDOM from 'react-dom';

import App from './App';

ReactDOM.render(<App />, document.getElementById('root'));

This code mounts the App component into the DOM element with the ID root.

11. JSX (JavaScript XML)

Definition: JSX is a syntax extension for JavaScript that looks similar to HTML. It allows developers to write HTML elements and components in a JavaScript file.

Example:

const element = <h1>Hello, World!</h1>;

How it Works:

JSX gets transpiled into JavaScript code using Babel.
Transpiled code uses React.createElement() to create React elements.

Transpiled Example:

const element = React.createElement('h1', null, 'Hello, World!');

Summary

Creating a React JS project involves several steps depending on the setup method. Using create-react-app simplifies the process by providing a pre-configured environment. Alternatively, setting up with Webpack and Babel offers more control but requires additional configuration. Understanding the folder structure, DOM vs. Virtual DOM, and React’s rendering process is crucial for effective development. The Virtual DOM improves performance by minimizing direct DOM manipulation, and React’s tools like StrictMode help in identifying potential issues. JSX makes writing

Module Import - Export

Understanding module import and export is crucial for structuring and organizing code in modern JavaScript applications. This guide explains modules, export and import mechanisms, and their various types.

What is a Module?

A module is a self-contained piece of code that can be reused across different parts of an application. It encapsulates functionality by exporting data, functions, or classes and importing them into other files. Modules help in organizing code into manageable sections and promote code reuse.

What is Export?

The export keyword is used to expose variables, functions, or classes from a module so they can be imported and used in other modules. There are two main types of exports in JavaScript: default exports and named exports.

Module - Export

Types of Export

Default Export

A module can have one default export. Default exports are useful when you want to export a single entity from a module.
Syntax:

// file: module.js

const greeting = 'Hello, World!';

export default greeting;

Named Export

A module can have multiple named exports. Named exports are used to export multiple entities from a module, each with its own name.
Syntax:

// file: module.js

export const greeting = 'Hello, World!';

export const farewell = 'Goodbye, World!';

Module - Default Export

Example:

// file: math.js

const add = (a, b) => a + b;

export default add;

Usage:

// file: app.js

import add from './math';

console.log(add(2, 3)); // Output: 5

Module - Named Export

Example:

// file: math.js

export const add = (a, b) => a + b;

export const subtract = (a, b) => a - b;

Usage:

// file: app.js

import { add, subtract } from './math';

console.log(add(2, 3)); // Output: 5

console.log(subtract(5, 3)); // Output: 2

Module - Import

Types of Import

Default Import

Used to import the default export from a module.
Syntax:

import someVariable from './module';

Named Import

Used to import specific named exports from a module.
Syntax:

import { someVariable } from './module';

Module - Importing Default

Example:

// file: math.js

const multiply = (a, b) => a * b;

export default multiply;

Usage:

// file: app.js

import multiply from './math';

console.log(multiply(2, 3)); // Output: 6

Module - Importing Named

Example:

// file: math.js

export const divide = (a, b) => a / b;

Usage:

// file: app.js

import { divide } from './math';

console.log(divide(6, 3)); // Output: 2

Module - Importing All

Purpose: Allows importing all named exports from a module as a single object.
Syntax:

import * as math from './math';

Example:

// file: math.js

export const add = (a, b) => a + b;

export const subtract = (a, b) => a - b;

Usage:

// file: app.js

import * as math from './math';

console.log(math.add(2, 3)); // Output: 5

console.log(math.subtract(5, 3)); // Output: 2

Module - Importing Default & Named

Example:

// file: math.js

const multiply = (a, b) => a * b;

const divide = (a, b) => a / b;

export default multiply;

export { divide };

Usage:

// file: app.js

import multiply, { divide } from './math';

console.log(multiply(2, 3)); // Output: 6

console.log(divide(6, 3)); // Output: 2

Summary

Modules in JavaScript help organize code by encapsulating functionality and allowing it to be shared across different parts of an application. Using the export keyword, you can expose variables, functions, or classes from a module, and with the import keyword, you can bring these entities into other modules. There are two primary types of exports: default and named, and corresponding import types: default import, named import, and importing all named exports. Understanding these concepts allows for better modularization, code reuse, and maintainability in JavaScript applications.

ES6/ES7/ES8: Key Features and Concepts

ECMAScript (often abbreviated as ES) is the standard specification that JavaScript follows. New versions of ECMAScript introduce various features and improvements to the language. Let's delve into some of the key features introduced in ES6 (ECMAScript 2015), ES7 (ECMAScript 2016), and ES8 (ECMAScript 2017).

1. What is ECMAScript?

ECMAScript is a scripting language specification that JavaScript adheres to. It standardizes the core features of JavaScript and is maintained by ECMA International. Each edition of ECMAScript introduces new features and improvements.

2. ECMAScript Editions

ES5 (ECMAScript 5): Published in 2009, it introduced features like strict mode, JSON support, and more array methods.
ES6 (ECMAScript 2015): Introduced major features such as let, const, arrow functions, and classes.
ES7 (ECMAScript 2016): Added features like the exponentiation operator and Array.prototype.includes.
ES8 (ECMAScript 2017): Introduced async functions, Object.entries(), Object.values(), and more.

3. var, let, & const

var: Function-scoped variable declaration. Variables declared with var can be re-declared and updated within their scope.

var x = 10;

if (true) {

var x = 20; // same variable

}

console.log(x); // Output: 20

let: Block-scoped variable declaration. Variables declared with let cannot be re-declared within the same scope.

let y = 10;

if (true) {

let y = 20; // different variable

}

console.log(y); // Output: 10

const: Block-scoped constant declaration. Variables declared with const must be initialized and cannot be reassigned.

const z = 10;

// z = 20; // Error: Assignment to constant variable.

4. Template Literals in JavaScript

Template literals provide a way to embed expressions into strings and create multi-line strings. They use backticks (`) instead of quotes.

Example:

const name = 'Alice';

const greeting = `Hello, ${name}!`;

console.log(greeting); // Output: Hello, Alice!

Methods:

Tagged Templates: Allows customization of template literals.

function tag(strings, ...values) {

console.log(strings, values);

}

tag`Hello ${name}`; // Outputs: ["Hello ", ""], ["Alice"]

5. Array Destructuring

Array destructuring allows unpacking values from arrays into distinct variables.

Example:

const [a, b] = [1, 2];

console.log(a, b); // Output: 1 2

With Default Values:

const [x = 10, y = 20] = [1];

console.log(x, y); // Output: 1 20

6. Object Destructuring

Object destructuring allows unpacking properties from objects into distinct variables.

Example:

const person = { name: 'John', age: 30 };

const { name, age } = person;

console.log(name, age); // Output: John 30

With Default Values:

const { name = 'Unknown', age = 0 } = {};

console.log(name, age); // Output: Unknown 0

7. Default Parameters

Default parameters allow functions to have default values if no arguments are provided.

Example:

function greet(name = 'Guest') {

return `Hello, ${name}`;

}

console.log(greet()); // Output: Hello, Guest

8. Rest Parameters

Rest parameters allow functions to accept an indefinite number of arguments as an array.

Example:

function sum(...numbers) {

return numbers.reduce((acc, curr) => acc + curr, 0);

}

console.log(sum(1, 2, 3, 4)); // Output: 10

9. Fat Arrow Function

Arrow functions provide a shorter syntax for writing functions and inherit the this value from their enclosing context.

Example:

const add = (a, b) => a + b;

console.log(add(2, 3)); // Output: 5

Without Parameters:

const greet = () => 'Hello';

console.log(greet()); // Output: Hello

10. Spread Operator

The spread operator (...) allows expanding elements of an array or object into individual elements.

Example with Arrays:

const nums = [1, 2, 3];

const moreNums = [0, ...nums, 4];

console.log(moreNums); // Output: [0, 1, 2, 3, 4]

Example with Objects:

const obj1 = { a: 1, b: 2 };

const obj2 = { ...obj1, c: 3 };

console.log(obj2); // Output: { a: 1, b: 2, c: 3 }

11. Math.sign()

Returns the sign of a number, indicating whether it is positive, negative, or zero.

Example:

console.log(Math.sign(-10)); // Output: -1

console.log(Math.sign(0)); // Output: 0

console.log(Math.sign(10)); // Output: 1

12. Math.trunc()

Returns the integer part of a number by removing any fractional digits.

Example:

console.log(Math.trunc(4.9)); // Output: 4

console.log(Math.trunc(-4.9)); // Output: -4

13. Exponentiation Operator

The exponentiation operator (**) raises the base to the exponent power.

Example:

console.log(2 ** 3); // Output: 8

14. Numbers & Global Methods

isFinite() Method: Checks if a value is a finite number.

Example:

console.log(isFinite(2 / 0)); // Output: false

console.log(isFinite(2 / 1)); // Output: true

isNaN() Method: Checks if a value is NaN (Not-a-Number).

Example:

console.log(isNaN('hello')); // Output: true

console.log(isNaN(123)); // Output: false

Number.isInteger() Method: Checks if a value is an integer.

Example:

console.log(Number.isInteger(4)); // Output: true

console.log(Number.isInteger(4.5)); // Output: false

15. Class

Classes provide a blueprint for creating objects with shared properties and methods. They simplify the creation of objects and inheritance.

Example:

class Person {

constructor(name, age) {

this.name = name;

this.age = age;

}

greet() {

return `Hello, my name is ${this.name}`;

}

const person = new Person('Alice', 30);

console.log(person.greet()); // Output: Hello, my name is Alice

16. Callback Hell in JavaScript

Callback hell refers to the situation where multiple nested callbacks make code difficult to read and maintain.

Example:

doSomething(function(err, result) {

if (err) {

// handle error

} else {

doSomethingElse(result, function(err, result) {

if (err) {

// handle error

} else {

// more nested callbacks

}

});

}

});

17. Promises in JavaScript

Promises represent the eventual completion (or failure) of an asynchronous operation and its resulting value.

Example:

const promise = new Promise((resolve, reject) => {

setTimeout(() => resolve('Done!'), 1000);

});

promise.then(result => console.log(result)); // Output: Done!

18. Async Await in JavaScript

Async/await syntax simplifies working with promises by making asynchronous code look synchronous.

Example:

async function fetchData() {

const response = await fetch('https://api.example.com/data');

const data = await response.json();

return data;

}

fetchData().then(data => console.log(data));

19. Generators in ES6 JavaScript

Normal Functions: Execute from start to finish and return a result.
Generators: Special type of function that can be paused and resumed. They use the function* syntax and yield keyword.

Example:

function* generator() {

yield 1;

yield 2;

yield 3;

}

const gen = generator();

console.log(gen.next().value); // Output: 1

console.log(gen.next().value); // Output: 2

console.log(gen.next().value); // Output: 3

Summary

ECMAScript introduces enhancements to JavaScript, with ES6, ES7, and ES8 bringing significant improvements. Key features include:

Variables: let and const for block-scoped variables, var for function-scoped.
Template Literals: For easier string interpolation and multi-line strings.
Destructuring: For easier extraction of values from arrays and objects.
Default and Rest Parameters: For handling function arguments.
Arrow Functions and Spread Operator: For concise syntax and expanded functionality.
Math Methods and Class Syntax: For better mathematical operations and object-oriented programming.
Async/Await and Promises: For handling asynchronous operations more effectively.

JSX in Depth

JSX (JavaScript XML) is a syntax extension for JavaScript commonly used with React. It allows you to write HTML-like code within JavaScript, making it easier to create React elements and components. Let’s explore JSX in depth, including its syntax, features, and common practices.

1. JSX: Single Element

JSX allows you to create React elements using an HTML-like syntax. Each JSX expression must have a single root element.

Example:

Jsx

const element = <h1>Hello, world!</h1>;

This JSX code represents a React element that renders an <h1> HTML element with the text "Hello, world!".

2. JSX: Nested Elements

You can nest JSX elements within each other to build more complex UIs. Just like HTML, JSX supports nested tags.

Example:

Jsx

const element = (

<div>

<h1>Hello, world!</h1>

<p>This is a paragraph.</p>

</div>

);

Here, the <div> element contains an <h1> and a <p> element.

3. Expressions in JSX

JSX allows you to embed JavaScript expressions inside curly braces {}. This is useful for dynamically inserting values.

Example:

Jsx

const name = 'Alice';

const element = <h1>Hello, {name}!</h1>;

The {name} expression evaluates to "Alice", so the rendered output is <h1>Hello, Alice!</h1>.

4. Elements Must Be Closed

In JSX, every tag must be properly closed. This includes self-closing tags like <img> or <input>.

Example:

Jsx

const element = (

<div>

</div>

);

In this example, both <img> and <input> are self-closing and must end with a slash (/).

5. Attributes

Attributes in JSX are similar to HTML attributes but with some differences.

As String Literals

Attributes can be set as string literals, just like in HTML.

Example:

Jsx

const element = <a href="https://www.example.com">Example</a>;

As Expressions

You can use curly braces {} to embed JavaScript expressions in attributes.

Example:

Jsx

const link = 'https://www.example.com';

const element = <a href={link}>Example</a>;

Here, the href attribute is set using a JavaScript variable.

6. The style Attribute Changes Its Semantics

In JSX, inline styles are specified as an object rather than a string.

Example:

Jsx

const style = { color: 'blue', backgroundColor: 'lightgray' };

const element = <div style={style}>Styled Text</div>;

Here, the style attribute is an object with camelCase properties.

7. Comments

You can add comments in JSX using curly braces {}.

Example:

Jsx

const element = (

<div>

{/* This is a comment */}

<h1>Hello, world!</h1>

</div>

);

Comments inside JSX are wrapped in curly braces and are useful for adding notes or explanations.

8. JSX Does Not Allow if-else Statements

JSX does not support if-else statements directly. Instead, you can use conditional expressions like the ternary operator or logical operators.

Example with Ternary Operator:

Jsx

const isLoggedIn = true;

const element = (

<div>

{isLoggedIn ? <p>Welcome back!</p> : <p>Please log in.</p>}

</div>

);

Example with Logical && Operator:

Jsx

const showMessage = true;

const element = (

<div>

{showMessage && <p>This will be shown if true.</p>}

</div>

);

9. camelCase is the New Standard

JSX attributes use camelCase rather than the lowercase style used in HTML. For example, class in HTML becomes className in JSX.

Example:

Jsx

const element = <div className="my-class">Hello</div>;

10. Naming Convention

When using JSX, adhere to naming conventions:

Use camelCase for attribute names.
Use PascalCase for component names.

Example:

Jsx

function MyComponent() {

return <div className="my-component">Content</div>;

}

11. How to Loop in JSX

To loop through data in JSX, you typically use JavaScript’s array methods like map(). This allows you to dynamically generate elements based on data.

Example:

Jsx

const items = ['Apple', 'Banana', 'Cherry'];

const listItems = items.map((item, index) => <li key={index}>{item}</li>);

const element = (

<ul>

{listItems}

</ul>

);

In this example, items.map() creates a list of <li> elements, each representing an item from the items array.

Summary

JSX extends JavaScript by allowing you to write HTML-like syntax within JavaScript. It simplifies the process of creating and managing React elements and components. Key points include:

Single and Nested Elements: JSX can represent a single root element or nested elements.
Expressions: JavaScript expressions can be embedded within JSX.
Element Closure: All JSX tags must be properly closed.
Attributes: Attributes in JSX can be string literals or expressions.
Inline Styles: The style attribute uses JavaScript objects.
Comments: Comments are added using curly braces.
Conditional Rendering: Use ternary operators or logical operators for conditional rendering.
camelCase: JSX attributes use camelCase naming conventions.
Looping: Use JavaScript array methods like map() to dynamically generate elements.

Babel in React JS

What is Babel?

Babel is a JavaScript compiler that is widely used in modern web development to convert code written in ECMAScript 6 (or higher) and JSX (a syntax extension used in React) into JavaScript that is compatible with older browsers or environments.

Key Functions of Babel:

Transform Syntax: Babel can convert newer JavaScript syntax into older syntax that is more broadly supported by different browsers. For example, it can convert arrow functions and classes into ES5 syntax.
Polyfill Features: Babel can include polyfills for newer JavaScript features that aren't natively supported in the target environment. This ensures that the code can use features like Array.prototype.includes or Promise without breaking in older environments.
Convert JSX Syntax: JSX is a syntax extension for JavaScript that looks similar to HTML and is used in React to describe what the UI should look like. Babel transforms JSX into regular JavaScript function calls (e.g., React.createElement), making it possible for browsers to understand and render React components.

Webpack in React JS

What is Webpack?

Webpack is a module bundler for JavaScript applications. It takes modules with dependencies and generates static assets representing those modules. In the context of React, Webpack bundles JavaScript files, CSS, and other assets, making it possible to load them efficiently.

Key Functions of Webpack:

Bundling: Webpack combines all the JavaScript modules, styles, and assets into a single or a few bundled files. This helps in reducing the number of HTTP requests and improving load times.
Loaders: Loaders in Webpack allow you to preprocess files before they are added to the bundle. For example, you can use Babel with a Webpack loader to transpile JSX and ES6 code into ES5.
Plugins: Webpack plugins can be used to optimize the build process, such as minifying the code, generating source maps, or defining environment variables.

Real-Time Example

Imagine you have a React application with some JSX and ES6 features:

Code Example:

Jsx

// src/App.js

import React from 'react';

const App = () => (

<div>

<h1>Hello, World!</h1>

<p>Welcome to React with Webpack and Babel!</p>

</div>

);

export default App;

Webpack Configuration: Your Webpack configuration might look like this:

Javascript

// webpack.config.js

const path = require('path');

module.exports = {

entry: './src/index.js',

output: {

path: path.resolve(__dirname, 'dist'),

filename: 'bundle.js'

module: {

rules: [

{

test: /\.js$/,

use: {

loader: 'babel-loader',

options: {

presets: ['@babel/preset-react', '@babel/preset-env']

}

]

}

};

Babel Configuration: Your Babel configuration might be in a .babelrc file:

Json

{

"presets": ["@babel/preset-react", "@babel/preset-env"]

}

In this setup:

Webpack bundles all your JavaScript files, including React components.
Babel transpiles JSX and ES6 syntax to ensure compatibility with older browsers.

Summary

Babel is a JavaScript compiler used to convert modern JavaScript and JSX into compatible code for older environments. It transforms syntax, polyfills features, and converts JSX to JavaScript.
Webpack is a module bundler that combines various assets, such as JavaScript files and stylesheets, into a single or few bundles. It uses loaders to preprocess files (like using Babel to transpile code) and plugins to optimize the build.

React JS Overview

React is a popular JavaScript library for building user interfaces, primarily for single-page applications where you need a fast, interactive user experience.

Components in React JS

Types of Components

Functional Components:

Defined as JavaScript functions that return JSX.
Example:

Jsx

function Greeting(props) {

return <h1>Hello, {props.name}!</h1>;

}

Class Components:

ES6 classes that extend React.Component.
Example:

Jsx

class Greeting extends React.Component {

render() {

return <h1>Hello, {this.props.name}!</h1>;

}

Component Constructor

Purpose: Initializes state and binds methods in class components.
Example:

Jsx

class MyComponent extends React.Component {

constructor(props) {

super(props);

this.state = { count: 0 };

}

Components in Components

Components can be nested inside other components to build a tree of components.

Props in React JS

Props Data Types

String, Integer, Boolean, Array, Object, Function

Props in Function-Based Component

Accessed via function parameters.

Jsx

function Greeting(props) {

return <h1>Hello, {props.name}!</h1>;

}

Props in Class-Based Component

Accessed via this.props.

Jsx

class Greeting extends React.Component {

render() {

return <h1>Hello, {this.props.name}!</h1>;

}

Props are Read-Only

Props cannot be modified by the component receiving them.

Default Props

Provide default values for props.

Jsx

Greeting.defaultProps = {

};

Children Props (props.children)

Allows passing child elements to a component.

Jsx

function Container(props) {

return <div>{props.children}</div>;

}

PropTypes in React JS

PropTypes help validate props passed to a component.

Jsx

import PropTypes from 'prop-types';

MyComponent.propTypes = {

age: PropTypes.number.isRequired

};

State in React JS

Creating and Initializing State

Directly in Class Component:

Jsx

class MyComponent extends React.Component {

state = { count: 0 };

}

Inside Constructor:

jsx

Copy code

class MyComponent extends React.Component {

constructor(props) {

super(props);

this.state = { count: 0 };

}

Changing State

Using setState():

jsx

Copy code

this.setState({ count: this.state.count + 1 });

State vs. Props

Props: Passed from parent to child components, read-only.
State: Managed within a component, mutable.

React Events

Adding Events

React Event Declaration:

Jsx

<button onClick={this.handleClick}>Click Me</button>

Bind this

Binding in Constructor:

Jsx

constructor(props) {

super(props);

this.handleClick = this.handleClick.bind(this);

}

Arrow Functions:

Jsx

<button onClick={() => this.handleClick()}>Click Me</button>

Supported Events

React supports most HTML events like onClick, onChange, etc.

React Conditional Rendering

Jsx

if (this.state.isLoggedIn) {

return <Welcome />;

} else {

return <Login />;

}

Element Variables:

Jsx

const element = this.state.isLoggedIn ? <Welcome /> : <Login />;

Logical && Operator:

Jsx

{this.state.isLoggedIn && <Welcome />}

Ternary Operator:

Jsx

{this.state.isLoggedIn ? <Welcome /> : <Login />}

Switch Case:

Jsx

switch (this.state.page) {

case 'home':

return <Home />;

case 'about':

return <About />;

default:

return <NotFound />;

}

React Lists and Keys

Using map() in JSX

Example:

Jsx

const numbers = [1, 2, 3, 4];

const listItems = numbers.map((number) =>

<li key={number.toString()}>{number}</li>

);

Keys

Using Index (not recommended for dynamic lists):

Jsx

Using ID (preferred):

Jsx

React Styling

Inline CSS

Example:

Jsx

<div style={{ color: 'red' }}>Hello World</div>

Normal CSS (External Stylesheet)

Importing CSS:

Jsx

import './App.css';

CSS Modules

Usage:

Jsx

import styles from './App.module.css';

<div className={styles.container}>Hello World</div>

CSS-in-JS

Using Libraries: Styled-components, Emotion

React Router

Installation

Command:

Bash

npm install react-router-dom

Routes

Defining Routes:

Jsx

Navigation

Using Link Component:

Jsx

<Link to="/about">About</Link>

404 Page

Adding a 404 Page:

Jsx

Hooks in React JS

Use Cases

For managing state and side effects in functional components.

Built-in Hooks

useState:

jsx

const [count, setCount] = useState(0);

useEffect:

jsx

useEffect(() => {

document.title = `You clicked ${count} times`;

}, [count]);

useContext:

jsx

const context = useContext(MyContext);

Custom Hook

Example:

Jsx

function useWindowWidth() {

const [width, setWidth] = useState(window.innerWidth);

useEffect(() => {

function handleResize() {

setWidth(window.innerWidth);

}

window.addEventListener('resize', handleResize);

return () => window.removeEventListener('resize', handleResize);

}, []);

return width;

}

Context API

Using useContext

Example:

Jsx

const MyContext = React.createContext();

const value = useContext(MyContext);

Multiple Contexts

Combining Contexts:

Jsx

const combinedContext = useContext(ContextA) || useContext(ContextB);

useReducer Hook

Example:

Jsx

const [state, dispatch] = useReducer(reducer, initialState);

Forms in React JS

Controlled Components

Example:

Jsx

function MyForm() {

const [value, setValue] = useState('');

return (

<input type="text" value={value} onChange={(e) => setValue(e.target.value)} />

);

}

Uncontrolled Components

Example:

Jsx

function MyForm() {

const inputRef = useRef();

const handleSubmit = () => {

alert(inputRef.current.value);

};

return (

<div>

<button onClick={handleSubmit}>Submit</button>

</div>

);

}

React Component Lifecycle

Mounting

Methods: constructor(), render(), componentDidMount()

Updating

Methods: shouldComponentUpdate(), componentDidUpdate()

Unmounting

Method: componentWillUnmount()

React Component API

setState()

Usage:

Jsx

this.setState({ key: value });

forceUpdate()

Usage:

Jsx

this.forceUpdate();

Consuming APIs

Fetch API

Example:

Jsx

fetch('https://api.example.com/data')

.then(response => response.json())

.then(data => console.log(data));

Introduction to Redux

Redux is a predictable state container for JavaScript applications. It helps manage the state of your application in a single, immutable state tree, which makes it easier to debug and test. Redux is often used with React, but it can be used with any JavaScript framework or library.

Why Should I Use Redux?

Predictable State Management: Redux maintains the state of an entire application in a single store, making the flow of data predictable and easier to debug.
Centralized Store: State is kept in a single location, so changes are easier to track and manage.
Debugging: Tools like Redux DevTools provide powerful debugging capabilities.
Consistency: Redux helps maintain consistent data flow across the app by using actions and reducers.

What is React-Redux?

React-Redux is a library that helps connect React components to the Redux store. It provides a set of utilities to integrate Redux with React seamlessly.

Key Concepts in Redux:

Actions: Plain JavaScript objects that represent an event or an intention to change the state. They must have a type property that describes the action, and can have additional payload data.

Example:

Javascript

const ADD_TODO = 'ADD_TODO';

const addTodo = (text) => ({

type: ADD_TODO,

payload: text,

});

Reducers: Functions that specify how the state changes in response to actions. They take the current state and an action, and return a new state.

Example:

Javascript

const todosReducer = (state = [], action) => {

switch (action.type) {

case ADD_TODO:

return [...state, action.payload];

default:

return state;

}

};

Store: An object that holds the state of the application. The store is created using the createStore function from Redux and is where you register reducers.

Example:

Javascript

import { createStore } from 'redux';

const store = createStore(todosReducer);

Dispatch: A function that sends actions to the Redux store. Dispatching an action causes the reducer to process it and update the state accordingly.

Example:

Javascript

store.dispatch(addTodo('Learn Redux'));

Connect: A higher-order component provided by react-redux that connects a React component to the Redux store. It lets you map state and dispatch to the component’s props.

Example:

Javascript

import { connect } from 'react-redux';

const mapStateToProps = (state) => ({

todos: state,

});

const mapDispatchToProps = (dispatch) => ({

addTodo: (text) => dispatch(addTodo(text)),

});

export default connect(mapStateToProps, mapDispatchToProps)(TodoComponent);

Action Types: Constants that represent different action types. They help avoid typos and make actions more manageable.

Example:

Javascript

export const ADD_TODO = 'ADD_TODO';

Action Creators: Functions that create actions. They help encapsulate the creation of action objects.

Example:

Javascript

export const addTodo = (text) => ({

type: ADD_TODO,

payload: text,

});

Redux Dependencies

Redux: The core library for managing state.
React-Redux: Provides bindings to integrate Redux with React. It includes utilities like connect, Provider, and hooks like useSelector and useDispatch.
Redux Thunk: A middleware that allows you to write action creators that return a function instead of an action. This function can perform asynchronous operations before dispatching an action.

Example:

Javascript

const fetchTodos = () => {

return async (dispatch) => {

const response = await fetch('/todos');

const todos = await response.json();

dispatch({ type: 'SET_TODOS', payload: todos });

};

Redux DevTools Extension: A browser extension that provides a way to inspect and debug Redux state and actions.

What is Provider?

Provider is a component from react-redux that makes the Redux store available to any nested components that need to access it. It should be placed at the top level of your application.

Example:

Javascript

import { Provider } from 'react-redux';

import { store } from './store';

const App = () => (

</Provider>

);

Extending Redux Functionality

You can extend Redux’s functionality with middleware (like Redux Thunk for async operations) and enhancers (like Redux DevTools). You can also use libraries like reselect for creating memoized selectors.

Combine More Than One Reducer

You can use combineReducers to combine multiple reducers into a single reducer function.

Example:

Javascript

import { combineReducers } from 'redux';

const rootReducer = combineReducers({

todos: todosReducer,

visibilityFilter: visibilityFilterReducer,

});

const store = createStore(rootReducer);

useSelector and useDispatch Hooks in React-Redux

useSelector: A hook that allows you to extract data from the Redux store state. It takes a selector function and returns the selected state.

Example:

Javascript

import { useSelector } from 'react-redux';

const TodosList = () => {

const todos = useSelector((state) => state.todos);

return (

<ul>

{todos.map((todo, index) => (

))}

</ul>

);

};

useDispatch: A hook that provides a reference to the dispatch function. It allows you to dispatch actions from within a functional component.

Example:

Javascript

import { useDispatch } from 'react-redux';

const AddTodo = () => {

const dispatch = useDispatch();

const handleClick = () => {

dispatch(addTodo('New Todo'));

};

return <button onClick={handleClick}>Add Todo</button>;

};

Summary

Redux helps manage state in a predictable way with a single store.
React-Redux provides tools like connect, Provider, and hooks (useSelector, useDispatch) to connect React components with the Redux store.
Actions and reducers are central to Redux, defining how the state changes in response to events.
Store is where the state lives, dispatch is used to send actions, and Provider makes the store accessible to components.
Redux Thunk enables async operations, and Redux DevTools helps with debugging.
Use combineReducers to manage multiple reducers and extend functionality with middleware and libraries.

Third-Party Packages Implementation in React

React Table

Purpose: A library for creating customizable and efficient data tables.

Installation:

Bash

npm install react-table

Example:

Javascript

import { useTable } from 'react-table';

const Table = ({ columns, data }) => {

const { getTableProps, getTableBodyProps, headerGroups, rows, prepareRow } = useTable({ columns, data });

return (

<thead>

{headerGroups.map(headerGroup => (

{headerGroup.headers.map(column => (

<th {...column.getHeaderProps()}>{column.render('Header')}</th>

))}

</tr>

))}

</thead>

{rows.map(row => {

prepareRow(row);

return (

{row.cells.map(cell => (

<td {...cell.getCellProps()}>{cell.render('Cell')}</td>

))}

</tr>

);

})}

</tbody>

</table>

);

};

node-sass

Purpose: Allows you to use SCSS syntax in your stylesheets for better organization and modularity.

Installation:

Bash

npm install node-sass

Usage: Rename your CSS files to .scss and use SCSS syntax.

Example:

Scss

// styles.scss

$primary-color: #3498db;

.button {

background-color: $primary-color;

padding: 10px;

}

sweetalert2

Purpose: Provides beautiful and customizable alert dialogs.

Installation:

Bash

npm install sweetalert2

Example:

Javascript

import Swal from 'sweetalert2';

const showAlert = () => {

Swal.fire({

title: 'Success!',

text: 'You have successfully implemented SweetAlert2',

icon: 'success',

confirmButtonText: 'OK'

});

};

react-tabs

Purpose: Provides a simple way to create tabbed interfaces.

Installation:

Bash

npm install react-tabs

Example:

Javascript

import { Tabs, Tab } from 'react-tabs';

import 'react-tabs/style/react-tabs.css';

const MyTabs = () => (

<Tabs>

</TabList>

<h2>Content of Tab 1</h2>

</TabPanel>

<h2>Content of Tab 2</h2>

</TabPanel>

</Tabs>

);

react-responsive-modal

Purpose: A responsive modal component.

Installation:

Bash

npm install react-responsive-modal

Example:

Javascript

import { Modal } from 'react-responsive-modal';

import 'react-responsive-modal/styles.css';

const MyModal = ({ open, onClose }) => (

<h2>My Modal</h2>

</Modal>

);

React Feather Icons

Purpose: Provides a collection of Feather icons for use in React.

Installation:

Bash

npm install react-feather

Example:

Javascript

import { Camera, Search } from 'react-feather';

const IconComponent = () => (

<div>

</div>

);

React-Toastify

Purpose: Provides toast notifications for React.

Installation:

Bash

npm install react-toastify

Example:

Javascript

import { ToastContainer, toast } from 'react-toastify';

import 'react-toastify/dist/ReactToastify.css';

const notify = () => toast("Wow so easy!");

const App = () => (

<div>

<button onClick={notify}>Notify!</button>

</div>

);

React Count To

Purpose: Allows animated counting for numerical values.

Installation:

Bash

npm install react-count-to

Example:

Javascript

import CountTo from 'react-count-to';

const CountComponent = () => (

);

React Google Charts

Purpose: Provides a wrapper for Google Charts.

Installation:

Bash

npm install react-google-charts

Example:

Javascript

import { Chart } from 'react-google-charts';

const data = [

['Year', 'Sales'],

['2013', 1000],

['2014', 1170],

['2015', 660],

['2016', 1030],

];

const options = {

title: 'Company Performance',

curveType: 'function',

legend: { position: 'bottom' },

};

const MyChart = () => (

<Chart

chartType="LineChart"

data={data}

options={options}

width="100%"

height="400px"

legendToggle

);

react-helmet

Purpose: Manages the document head (meta tags, title, etc.) in React applications.

Installation:

Bash

npm install react-helmet

Example:

Javascript

import { Helmet } from 'react-helmet';

const MyComponent = () => (

<div>

<title>My Title</title>

</Helmet>

<h1>Hello, World!</h1>

</div>

);

react-slick

Purpose: A carousel component for React based on Slick.

Installation:

Bash

npm install react-slick slick-carousel

Example:

Javascript

import Slider from 'react-slick';

import 'slick-carousel/slick/slick.css';

import 'slick-carousel/slick/slick-theme.css';

const settings = {

dots: true,

infinite: true,

speed: 500,

slidesToShow: 1,

slidesToScroll: 1

};

const Carousel = () => (

<div><h3>Slide 1</h3></div>

<div><h3>Slide 2</h3></div>

<div><h3>Slide 3</h3></div>

</Slider>

);

React Multilingual with Redux

Purpose: Provides multilingual support in React applications using Redux for state management.

Installation:

Bash

npm install react-redux redux react-i18next i18next

Example:

Javascript

import i18n from 'i18next';

import { Provider, useDispatch } from 'react-redux';

import { createStore } from 'redux';

import { useTranslation } from 'react-i18next';

// i18n configuration

i18n.init({

resources: {

en: {

translation: {

"welcome": "Welcome"

}

fr: {

translation: {

"welcome": "Bienvenue"

}

lng: "en",

fallbackLng: "en"

});

const rootReducer = (state = { language: 'en' }, action) => {

switch (action.type) {

case 'SET_LANGUAGE':

return { ...state, language: action.payload };

default:

return state;

}

};

const store = createStore(rootReducer);

const LanguageSwitcher = () => {

const dispatch = useDispatch();

const { t } = useTranslation();

return (

<div>

<button onClick={() => dispatch({ type: 'SET_LANGUAGE', payload: 'en' })}>English</button>

<button onClick={() => dispatch({ type: 'SET_LANGUAGE', payload: 'fr' })}>French</button>

<p>{t('welcome')}</p>

</div>

);

};

const App = () => (

</Provider>

);

react-slide-toggle

Purpose: Provides a slide-toggle component for animations.

Installation:

Bash

npm install react-slide-toggle

Example:

Javascript

import SlideToggle from 'react-slide-toggle';

const SlideComponent = () => (

{({ toggle, setCollapsibleElement }) => (

<div>

<button onClick={toggle}>Toggle</button>

<p>Slide me!</p>

</div>

)}

</SlideToggle>

);

React Sticky Box

Purpose: Provides a sticky box component that stays in place as you scroll.

Installation:

Bash

npm install react-sticky-box

Example:

Javascript

import StickyBox from 'react-sticky-box';

const StickyComponent = () => (

I stay sticky!

</div>

</StickyBox>

);

react-infinite-scroll-component

Purpose: Provides infinite scrolling functionality.

Installation:

Bash

npm install react-infinite-scroll-component

Example:

Javascript

import InfiniteScroll from 'react-infinite-scroll-component';

const InfiniteComponent = () => {

const [items, setItems] = React.useState([...Array(20).keys()]);

const fetchData = () => {

setTimeout(() => {

setItems(items.concat([...Array(20).keys()]));

}, 1000);

};

return (

<InfiniteScroll

dataLength={items.length}

next={fetchData}

hasMore={true}

loader={<h4>Loading...</h4>}

{items.map((item, index) => (

))}

</InfiniteScroll>

);

};

react-input-range

Purpose: Provides a range slider component.

Installation:

Bash

npm install react-input-range

Example:

Javascript

import InputRange from 'react-input-range';

import 'react-input-range/lib/css/index.css';

const RangeSlider = () => {

const [value, setValue] = React.useState({ min: 0, max: 100 });

return (

<InputRange

maxValue={100}

minValue={0}

value={value}

onChange={value => setValue(value)}

);

};

Stripe Payment Gateway in React JS

Purpose: Allows integration with the Stripe payment gateway.

Installation:

Bash

npm install @stripe/stripe-js @stripe/react-stripe-js

Example:

Javascript

import { Elements, CardElement, useStripe, useElements } from '@stripe/react-stripe-js';

import { loadStripe } from '@stripe/stripe-js';

const stripePromise = loadStripe('your-public-key-here');

const CheckoutForm = () => {

const stripe = useStripe();

const elements = useElements();

const handleSubmit = async (event) => {

event.preventDefault();

if (!stripe || !elements) return;

const { error, paymentMethod } = await stripe.createPaymentMethod({

type: 'card',

card: elements.getElement(CardElement),

});

if (error) {

console.error(error);

} else {

console.log(paymentMethod);

}

};

return (

</form>

);

};

const App = () => (

</Elements>

);

Summary

React Table: Efficient data tables.
node-sass: SCSS support in stylesheets.
sweetalert2: Customizable alerts.
react-tabs: Tabbed interfaces.
react-responsive-modal: Responsive modals.
React Feather Icons: Feather icons for React.
React-Toastify: Toast notifications.
React Count To: Animated numerical counts.
React Google Charts: Google Charts integration.
react-helmet: Manage document head.
react-slick: Carousel component.
React Multilingual with Redux: Multilingual support with Redux.
react-slide-toggle: Slide-toggle animations.
React Sticky Box: Sticky box component.
react-infinite-scroll-component: Infinite scrolling.
react-input-range: Range sliders.
Stripe Payment Gateway: Stripe integration for payments.

Overview of JSON Web Tokens (JWT)

JSON Web Tokens (JWT) are a compact, URL-safe means of representing claims to be transferred between two parties. The claims in a JWT are encoded as a JSON object that is used as a payload of a JSON Web Signature (JWS) structure or as a JSON Web Encryption (JWE) structure, enabling the claims to be digitally signed or integrity protected with a Message Authentication Code (MAC) and/or encrypted.

JSON Web Tokens

Structure: A JWT consists of three parts, separated by dots (.):

1. Header: Contains metadata about the token. Typically, this includes the type of token (JWT) and the signing algorithm used (e.g., HMAC SHA256 or RSA).

2. Payload: Contains the claims, which are statements about an entity (typically, the user) and additional data. Claims are of three types: registered, public, and private.

3. Signature: Used to verify that the token hasn’t been altered. It’s created by taking the encoded header and payload, a secret key, and applying the algorithm specified in the header.

Example JWT:

eyJhbGciOiAiSFMyNTYiLCAic3RhdHVzIjogIkNPTVAtU1BBIn0.eyJzdWIiOiAiMTIzNDU2Nzg5MCIsICJuYW1lIjogIkpvaG4gRG9lIiwgImVtYWlsIjogImpvaG5AZG9lLmNvbSJ9.X4i66zS78YPL17dyzFWuUJmh9cGSbyD0b6LkftC_7rI

How JWT Tokens Are Used

JWTs are commonly used in authentication and authorization. Here’s how they typically work:

1. Authentication: After a user logs in with their credentials, the server generates a JWT and sends it to the client. The client then includes this token in the Authorization header of subsequent requests. The server validates the token and processes the request accordingly.

2. Authorization: JWTs can also be used to grant access to resources. For instance, a JWT might include claims about a user’s roles or permissions, which the server uses to determine if the user can access certain resources or perform specific actions.

Example:

1. User logs in:

Client sends a login request with username and password.
Server validates the credentials and generates a JWT.

2. Client receives the JWT:

JWT is stored in the client’s local storage or cookies.

3. Client makes an authenticated request:

Client includes the JWT in the Authorization header of the request.

Http

GET /api/user-profile

Authorization: Bearer <token>

4. Server validates the JWT:

Server extracts the JWT from the Authorization header.
Server verifies the token’s signature and checks the claims.

5. Server responds based on JWT validation:

If valid, the server processes the request.
If invalid, the server responds with an authentication error.

Adding JWT to HTTP Header

To send a JWT with an HTTP request, it is typically included in the Authorization header. The format is:

Http

Authorization: Bearer <token>

Example:

Javascript

fetch('https://api.example.com/user-profile', {

  method: 'GET',

  headers: {

    'Authorization': `Bearer ${token}`,  // Adding JWT to HTTP Header

    'Content-Type': 'application/json',

},

})

  .then(response => response.json())

  .then(data => console.log(data));

How The Server Makes Use of JWT Tokens

1. Token Extraction: The server extracts the JWT from the Authorization header of the incoming request.

2. Token Verification: The server verifies the token’s signature using the secret key (for HMAC) or public key (for RSA). This ensures the token is valid and hasn’t been tampered with.

3. Token Decoding: If the token is valid, the server decodes the payload to access the claims. The server can use these claims to determine the user’s identity and permissions.

4. Access Control: Based on the claims, the server decides whether to grant or deny access to the requested resource.

Example:

Server-side Implementation (Node.js with Express and jsonwebtoken library):

Javascript

const express = require('express');

const jwt = require('jsonwebtoken');

const app = express();

const SECRET_KEY = 'your-very-secret-key';

// Middleware to verify JWT

const authenticateToken = (req, res, next) => {

  const authHeader = req.headers['authorization'];

  const token = authHeader && authHeader.split(' ')[1];

  if (token == null) return res.sendStatus(401);

  jwt.verify(token, SECRET_KEY, (err, user) => {

    if (err) return res.sendStatus(403);

    req.user = user;

    next();

});

};

// Protected route

app.get('/user-profile', authenticateToken, (req, res) => {

  res.json({ message: 'This is your profile data.', user: req.user });

});

app.listen(3000);

Summary

JWT (JSON Web Tokens): Compact and URL-safe tokens used for securely transmitting information between parties.
Usage: Commonly used for authentication and authorization, allowing secure and stateless user sessions.
HTTP Header: JWT is added to requests in the Authorization header using the Bearer schema.
Server Handling: The server extracts the token, verifies its signature, decodes the payload, and uses the claims for access control.

FSPWD - Full Stack Python Web Development

Tuesday, October 8, 2024

React JS

Introducing React JS

Setup Environment for React JS

Setup/Create React JS Project

Module Import - Export

ES6/ES7/ES8: Key Features and Concepts

JSX in Depth

Babel in React JS

React JS Overview

Introduction to Redux

Third-Party Packages Implementation in React

Overview of JSON Web Tokens (JWT)

JSON Web Tokens

How JWT Tokens Are Used

Adding JWT to HTTP Header

How The Server Makes Use of JWT Tokens

Summary

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