Components in React JS: Functional vs Class

 Introduction

Components are the heart of every React application, allowing developers to break complex UIs into reusable, manageable pieces. In React, you can create components as either functional components or class components. While both serve the same purpose — rendering UI — they differ in syntax, capabilities, and how they handle state and lifecycle methods.

Functional Components

Functional components are simple JavaScript functions that accept props as input and return JSX to render UI. Before React 16.8, functional components were stateless, but with the introduction of Hooks, they can now manage state, side effects, and more.

Example:

function Welcome(props) {

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

}

Or using an arrow function:

const Welcome = ({ name }) => <h1>Hello, {name}!</h1>;

When to use functional components?

✅ When you need a simple component

✅ When you want to use Hooks for state or lifecycle (e.g., useState, useEffect)

✅ For better readability and shorter syntax

Class Components

Class components extend the React.Component class and include a render() method that returns JSX. They traditionally handled state and lifecycle methods like componentDidMount, shouldComponentUpdate, or componentWillUnmount.

Example:

import React, { Component } from 'react';

class Welcome extends Component {

  render() {

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

  }

}

When to use class components?

✅ If you’re maintaining older React codebases

✅ When you need traditional lifecycle methods without rewriting to Hooks

Functional vs Class Components: A Quick Comparison

Feature                       Functional Components             Class Components

Syntax                       Simple JS functions                     ES6 classes extending React.Component

State Management       Via Hooks (e.g., useState)     Via this.state and this.setState

Lifecycle                       With Hooks like useEffect     Traditional lifecycle methods

Performance               Slightly faster, lighter             Slightly heavier, more boilerplate

Recommended       ✅ Modern React (post-16.8)    🚫 Legacy code or rare use cases

Conclusion

While class components were the backbone of React applications in earlier versions, functional components with Hooks have become the modern standard. They offer cleaner syntax, improved performance, and more flexibility. For new React projects, functional components are the recommended approach — but understanding class components helps when working with or refactoring older codebases.

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What is React JS and Why Should You Learn It?

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