ReactJS Overview
1. Introduction to ReactJS
History of ReactJS: ReactJS was developed by Facebook in 2013 as a JavaScript library for building
user interfaces, especially for single-page applications.
Characteristics of ReactJS: React is component-based, declarative, and allows for building complex
UIs using reusable components.
Virtual DOM: React uses a virtual DOM for fast updates to the UI by comparing changes between
the actual DOM and virtual DOM.
2. Components in ReactJS
Functional Components: React supports functional components, which are JavaScript functions that
return JSX (JavaScript XML) for rendering the UI.
Class Components: React also allows for class components, which are ES6 classes extending
React.Component.
Component Lifecycle: Class components have lifecycle methods like componentDidMount,
componentDidUpdate, and componentWillUnmount.
3. JSX in ReactJS
JSX Syntax: JSX is a syntax extension for JavaScript that looks like HTML but is converted to
React.createElement calls behind the scenes.
Embedding Expressions: JSX allows embedding JavaScript expressions within curly braces for
dynamic content.
Conditional Rendering: JSX supports conditional rendering using if statements or the ternary
operator.
4. State and Props in ReactJS
State: State in React is an object that holds data specific to a component and can be updated using
the setState function in class components.
Props: Props are immutable properties passed from a parent component to a child component to
1. Introduction to ReactJS
History of ReactJS: ReactJS was developed by Facebook in 2013 as a JavaScript library for building
user interfaces, especially for single-page applications.
Characteristics of ReactJS: React is component-based, declarative, and allows for building complex
UIs using reusable components.
Virtual DOM: React uses a virtual DOM for fast updates to the UI by comparing changes between
the actual DOM and virtual DOM.
2. Components in ReactJS
Functional Components: React supports functional components, which are JavaScript functions that
return JSX (JavaScript XML) for rendering the UI.
Class Components: React also allows for class components, which are ES6 classes extending
React.Component.
Component Lifecycle: Class components have lifecycle methods like componentDidMount,
componentDidUpdate, and componentWillUnmount.
3. JSX in ReactJS
JSX Syntax: JSX is a syntax extension for JavaScript that looks like HTML but is converted to
React.createElement calls behind the scenes.
Embedding Expressions: JSX allows embedding JavaScript expressions within curly braces for
dynamic content.
Conditional Rendering: JSX supports conditional rendering using if statements or the ternary
operator.
4. State and Props in ReactJS
State: State in React is an object that holds data specific to a component and can be updated using
the setState function in class components.
Props: Props are immutable properties passed from a parent component to a child component to
