recat ppt

1. Javascript Versions : ECMAScript
ECMAScript (ES) is a standardized scripting language specification. This means
it's a set of documented rules that define the core features and syntax for a
scripting language.
Standardization , Foundation and Evolution
Example: universal recipe book for scripting languages

3. ECMAScript 6 (ES6 / ECMAScript 2015)
● Let and const
● Arrow functions
● Template literals
● Modules (import/export)
● Destructuring assignment
● Rest parameters and spread
operator

4. Introduction to Fetch API
● The Fetch API is a modern JavaScript interface for making HTTP requests to
interact with web servers.
● It is built into modern web browsers and allows you to make network requests
similar to XMLHttpRequest but with a cleaner and more powerful syntax using
Promises.

5. Features of Fetch API:
1. Promise-Based: Makes handling asynchronous requests easier.
2. Simple Syntax: Offers a cleaner, less verbose syntax compared to older
methods like XMLHttpRequest.
3. Supports JSON: Simplifies working with JSON data.
4. Wide Range of Use Cases: Can handle GET, POST, PUT, DELETE, and other
HTTP methods.
XML vs JSON

6. Basics of HTTP Requests
HTTP (Hypertext Transfer Protocol) is the foundation of any data exchange on the
web. It is a request-response protocol used by clients (like browsers) to
communicate with servers.

7. Key Components of HTTP Requests:
1. Request Methods:
a. GET: Retrieve data from a server.
b. POST: Send data to a server to create/update a resource.
c. PUT: Update an existing resource.
d. DELETE: Remove a resource.
e. Other methods: PATCH, OPTIONS, HEAD.

8. 2. Request Headers:
● Contain metadata for the request (e.g., content type, authentication tokens).
3. Request Body:
● Used to send data to the server (mainly with POST or PUT).
4. Response:
● Status Code: Indicates the result of the request (e.g., 200 OK, 404 Not Found).
● Headers: Provide metadata about the response.
● Body: Contains the actual data sent from the server.

9. Basic Syntax:
fetch(url, options)
.then(response => {
// Handle the response object
})
.catch(error => {
// Handle errors
});

10. Local Storage and Session Storage
Both Local Storage and Session Storage are part of the Web Storage API, which
provides a way to store key-value pairs in a web browser.
They are commonly used to store data on the client-side.

11. React Series

12. What is React ?
● React is a JavaScript library for building user interfaces, particularly for
single-page applications where reactivity and performance are key.
● It was developed by Facebook and is maintained by Facebook and a
community of individual developers and companies.
● React allows developers to create large web applications that can update and
render efficiently in response to data changes.

13. Why You Should Learn React
● High Demand
● Component-Based Architecture
● Fast Learning Curve
● Virtual DOM
● Large Ecosystem
● Community and Resources

14. Advantages of React
● Reusable components.
● Virtual DOM for efficient updates.
● Declarative UI for better code readability.
● Rich ecosystem (React Router, Redux, Next.js).
● Backward compatibility and stable APIs.
● Easy transition to React Native for mobile development.

15. Disadvantages of React
● Fast-paced ecosystem with frequent updates.
● JSX syntax can be challenging for beginners.
● Complex state management in large apps.
● Initial boilerplate setup can be extensive.
● SEO challenges with single-page applications.
● Incomplete framework, requiring third-party tools for routing and state.

16. Key Features of React:
● Component-Based Architecture
● JSX (JavaScript XML)
● Virtual DOM
● Unidirectional Data Flow
● Declarative Programming

17. Component-Based Architecture
● Reusable, self-contained UI pieces
● Components maintain their own state
● Components can be composed to build complex interfaces

18. JSX (JavaScript XML)
● Syntax extension that resembles HTML
● Allows writing HTML-like code within JavaScript
● Transformed into JavaScript by tools like Babel
● Enhances code readability and writability

19. Virtual DOM
● Lightweight representation of the actual DOM.
● Updates virtual DOM first when state changes.
● Efficiently calculates and applies changes to the actual DOM.
● Improves performance by minimizing DOM manipulation.

20. Unidirectional Data Flow
● Data flows in one direction, from parent to child components via props
● Simplified understanding of how data changes affect the application
● Enhances predictability of data flow

21. Declarative Programming
● Developers describe the UI for a given state
● React handles UI updates when the state changes
● Makes code more predictable and easier to debug

22. Getting Started
● Setting up the development environment
● Creating your first React app using Create React App (CRA) and Vite
● Understanding the project structure

23. Understanding the React Project Structure

24. Default Vite + React Project Structure

26. Folder & File Breakdown
✅ public/
Contains static files (e.g., images, favicon)
Anything in here is accessible via /filename.ext
⚠ Unlike CRA, Vite doesn’t automatically copy everything from public/ to dist/
unless used.

27. ✅ index.html
● This is the entry HTML file
● Vite injects the React app into the div#root
● You also link metadata and fonts here
✅ src/
All your main React code goes here.

28. JavaScript Essentials for React

29. Before start with learn
● Arrow Functions (=>)
● let and const
● Template Literals
● Destructuring
● Default Parameters
● Rest/Spread Operator (...)
● Modules (import/export)

30. ● Promises
● Async/Await
● Map, Filter, and Reduce
● Optional Chaining (?.)
● Nullish Coalescing Operator (??)

31. React Fundamentals

32. React JSX
What is JSX?
● JSX (JavaScript XML) is a syntax extension for JavaScript used with React
that allows you to write HTML-like code within JavaScript.
● JSX makes it easier to create React elements and components by combining
HTML-like markup with JavaScript logic.

33. React Props
● Props (short for "properties") in React are used to pass data from a parent
component to a child component.
● They allow you to configure and customize child components with dynamic
values.

34. Key Points About Props:
● Data Flow: Pass data from parent to child components.
● Read-Only: Props are immutable within the child component.
● Passing Data: Use attributes in JSX to pass props to child components.
● Accessing Props: Access via props object in functional components or
this.props in class components.

35. ● Default Props: Set default values for props using defaultProps.
● Prop Types: Validate prop types using prop-types library.
● Customizable Components: Customize child components with different data.
● Dynamic Rendering: Render dynamic content based on props.
● Reusability: Create reusable components that adapt to different data values.

36. Lifecycle in react
● In React, the component lifecycle refers to the series of methods that are
invoked at different stages of a component’s existence—from creation to
destruction.
● This lifecycle can be divided into three main phases:

37. 1. Mounting (when the component is created and inserted into the DOM)
2. Updating (when props or state changes)
3. Unmounting (when the component is removed from the DOM)
React Functional Component Lifecycle (with Hooks)
If you're using functional components with Hooks, the lifecycle is handled with
useEffect():

38. React Components
● A component is a JavaScript function or class that returns JSX (HTML-like
syntax) to render UI on the screen.
● Think of it like a custom HTML element.
○ Class Components
○ Functional Components

39. Styling React Using CSS
1. CSS Stylesheets (Traditional Way)
You can write CSS in a .css file and import it into your React component.
2. Inline Styles
Pass a style object directly to the style prop.
<h1 style={headingStyle}>Styled Inline</h1>

40. 3. CSS Modules
Scoped styles specific to a component. File name should end with
.module.css.
4. Styled Components (CSS-in-JS)
A library that lets you write CSS inside your JS files using tagged template
literals.
5. Tailwind CSS (Utility-First Framework)

42. React Events
● React events are how you handle user actions—like clicks, typing, or submitting a
form.
● Just like in HTML and JavaScript, React lets you listen for things like:
○ Clicking a button
○ Typing in an input
○ Hovering over an element
○ Submitting a form
● But in React, the way you write these events is slightly different.

43. Basic Rules
1. Use camelCase for event names
onClick, onChange, onSubmit
(Not like HTML where it’s lowercase, e.g., onclick)
2. Pass a function, not a string
→ ✅ onClick={handleClick}
→ ❌ onClick="handleClick()"

44. Example 1: Click Event
function App() {
function handleClick() {
alert('Button was clicked!');
}
return <button onClick={handleClick}>Click Me</button>;
}

45. React Lists
1. In React, a list is usually an array of items (like names, products, posts, etc.)
that you want to show on the screen.
2. To display them, we use JavaScript’s .map() method to loop through the array
and create JSX elements for each item.

46. Example: Rendering a Simple List
function App() {
const fruits = ['Apple', 'Banana', 'Mango'];
return (
<ul>
{fruits.map((fruit, index) => (
<li key={index}>{fruit}</li>
))}
</ul>
);
}

47. What is key in React Lists?
● The key is a unique identifier for each item.
● Helps React know which item changed, added, or removed.
● You should not use index as a key if the list can change (e.g.,
items can be deleted/added).
<li key={fruit.id}>{fruit.name}</li>

49. React Table
● A React table is just like an HTML table — it uses <table>, <thead>, <tbody>,
<tr>, <th>, and <td> tags.
● We use JavaScript’s .map() to loop through data and create rows
dynamically.

50. React Forms
● React Forms – one of the most important parts of building interactive web
apps.
● A form lets users input data — like text, numbers, or selections — and then
handle that data using React state and events.
● React forms are controlled using state and event handlers.

51. React Conditional Rendering
1. Using If/Else Statements
2. Using Ternary Operator
3. Using Logical AND (&&) Operator
4. Using Switch Statements
5. Rendering Different Components Based on State or Props
6. Using the null for No Rendering

52. Routing in React

53. React Router is a standard library used in React to handle routing in a
Single Page Application (SPA).
In simple words: 👉 It helps you navigate between different pages
(components) in your React app without reloading the whole page.

54. Private Routes (for authentication)
Private Routes (also called Protected Routes) are routes that can only be
accessed by users who are logged in or authorized.
If the user is not authenticated, they will be redirected to the Login page (or any
other page you want).

55. What is Role-Based Routing?
Role-Based Routing means: ✅ Different types of users (Admin, User, Manager, Guest, etc.)
✅ Each role can access specific routes/pages
✅ Unauthorized users are restricted or redirected
Example:
/admin → Only Admins
/dashboard → Admin & User
/profile → All users

56. Authentication and Authorization
Authentication = Who are you?
It is the process of verifying the user's identity. You check if the user is valid or not using:
● Email & Password
● OTP
● Google / Facebook login
● API Token

57. Example:
When you log in to Instagram → They check if your username & password is
correct → That’s
Authentication.

58. What is Authorization?
Authorization = What can you do?
It is the process of checking the user's permissions after they are authenticated. Basically, what parts of the app the user is allowed to access based on their role.
Example:
● In an app:
● Admin → Can delete users, see all data
● Normal User → Can only see their own profile That permission check is Authorization.

59. Simple Difference

60. React Hooks

61. React Hooks
React Hooks are a way to use state and other React features without writing a
class.
They were introduced in React 16.8 and make it easier to manage state, side
effects, and context in functional components.

62. Core hooks
● useState: Allows you to add state to functional components.
● useEffect: Handles side effects like data fetching, subscriptions, and
manually changing the DOM.
● useContext: Provides access to context values without needing to
wrap components in Context.Consumer.

63. ● useReducer: Manages more complex state logic using a reducer function,
similar to Redux.
● useCallback: Returns a memoized callback function, useful to optimize
performance by avoiding unnecessary re-renders.

64. ● useMemo: Returns a memoized value, which helps in optimizing performance
for expensive calculations.
● useRef: Provides a way to persist values across renders and access DOM
elements directly.