React.js Complete Guide: What It Is, Why It’s Used, Who Created It, and Essential Hooks

What is React? Why is it Used? Who Created It? And Understanding React Hooks

Introduction

React is one of the most popular JavaScript libraries used for building modern web applications. From social media platforms to e-commerce websites, React powers thousands of applications worldwide because of its speed, flexibility, and component-based architecture.

In this article, we will explore what React is, why it is used, who created it, and some of the most important React Hooks such as useState, useEffect, useContext, useNavigate, useReducer, useRef, useMemo, and useCallback.

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What is React?

React is an open-source JavaScript library used for building user interfaces (UI), especially for Single Page Applications (SPAs).

Instead of updating an entire webpage, React updates only the parts of the page that change, making applications faster and more efficient.

Key Features of React

• Component-Based Architecture
• Virtual DOM
• Reusable Components
• One-Way Data Binding
• Fast Rendering
• Large Community Support

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Who Created React?

React was created by , a software engineer at "about.meta.com" (https://reference-url-citation.invalid/1).

Timeline

• 2011 – React was first used internally by Facebook.
• 2012 – Used in Instagram.
• 2013 – Released as an open-source project.
• Today – Used by companies around the world.

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Why is React Used?

React became popular because it solves many challenges in traditional web development.

1. Reusable Components

Developers can create a component once and use it multiple times.

Example:

function Welcome() {
return

Welcome User

;
}

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1. Better Performance

React uses a Virtual DOM to update only changed elements instead of refreshing the entire page.

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1. Easy Maintenance

Applications are divided into smaller components, making code easier to manage.

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1. Strong Community Support

Millions of developers contribute tutorials, libraries, and tools.

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1. Rich Ecosystem

React works well with:

• Redux
• React Router
• Axios
• Firebase
• Node.js

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What are React Hooks?

Hooks are special functions introduced in React 16.8 that allow developers to use state and other React features inside functional components.

Before Hooks, these features were available only in class components.

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1. useState Hook

The useState Hook is used to manage state in functional components.

Syntax

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

Example

import { useState } from "react";

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

return (
<>

{count}

setCount(count + 1)}>
Increment

</>
);
}

Use Cases

• Counter applications
• Form handling
• Toggle buttons

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1. useEffect Hook

The useEffect Hook is used to perform side effects.

Examples:

• API Calls
• Timers
• Event Listeners
• Updating Document Title

Example

import { useEffect } from "react";

function App() {
useEffect(() => {
console.log("Component Mounted");
}, []);

return

Hello React

;
}

Use Cases

• Fetching data
• Browser events
• Synchronizing external systems

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1. useContext Hook

The useContext Hook allows data sharing across multiple components without prop drilling.

Example

const UserContext = createContext();

function Home() {
const user = useContext(UserContext);

return

{user}

;
}

Use Cases

• Authentication
• Theme management
• Language settings

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1. useNavigate Hook

The useNavigate Hook is provided by React Router.

It allows navigation between pages programmatically.

Example

import { useNavigate } from "react-router-dom";

function Home() {
const navigate = useNavigate();

return (
navigate("/about")}>
Go To About

);
}

Use Cases

• Login redirection
• Navigation after form submission

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1. useReducer Hook

useReducer is used for complex state management.

Syntax

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

Example

function reducer(state, action) {
switch(action.type) {
case "increment":
return { count: state.count + 1 };
default:
return state;
}
}

Use Cases

• Shopping carts
• Dashboards
• Complex forms

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1. useRef Hook

useRef creates a mutable reference that persists across renders.

Example

import { useRef } from "react";

function InputFocus() {
const inputRef = useRef();

const focusInput = () => {
inputRef.current.focus();
};

return (
<>

Focus
</>
);
}

Use Cases

• DOM access
• Focus management
• Storing previous values

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1. useMemo Hook

useMemo is used to optimize performance by memoizing expensive calculations.

Example

const result = useMemo(() => {
return heavyCalculation(data);
}, [data]);

Use Cases

• Large datasets
• Filtering operations
• Expensive calculations

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1. useCallback Hook

useCallback memoizes functions to prevent unnecessary re-creation.

Example

const handleClick = useCallback(() => {
console.log("Clicked");
}, []);

Use Cases

• Optimizing child components
• Preventing unnecessary renders

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Difference Between useMemo and useCallback

useMemo| useCallback
Memoizes values| Memoizes functions
Returns computed value| Returns function
Used for calculations| Used for event handlers

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Advantages of React

• Fast Performance
• Reusable Components
• Easy Learning Curve
• Strong Community
• Rich Ecosystem
• SEO Friendly
• Scalable Applications

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