Functional vs Class Components Explained

⚛️ Functional vs Class Components Explained

React offers two primary ways to create components: Functional Components and Class Components. While both are capable of rendering UI and handling logic, they differ in syntax, structure, and how they manage state and side effects. With the arrival of Hooks, functional components have become the preferred choice in modern React development. Let’s dive deep into both.

🧩 What Are Functional Components?

Functional components are simple JavaScript functions that return JSX. They're easier to write, read, and test — and now, with Hooks, they can handle complex logic just like class components.

const Greeting = ({ name }) => {
  return <h2>Hello, {name}!</h2>;
};

Earlier, functional components were known as “stateless components,” but with useState and useEffect, they’re now fully capable of handling dynamic behavior.

🏛️ What Are Class Components?

Class components are based on ES6 classes and extend from React.Component. They have access to state, lifecycle methods, and are more verbose by nature.

class Greeting extends React.Component {
  render() {
    return <h2>Hello, {this.props.name}!</h2>;
  }
}

While class components were once the only way to manage state and lifecycle events, they’re now often replaced by functional components and hooks in most new codebases.

🧠 Managing State in Components

In class components: you manage state with this.state and update it using this.setState().

class Counter extends React.Component {
  constructor() {
    super();
    this.state = { count: 0 };
  }

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

  render() {
    return <button onClick={this.increment}>Count: {this.state.count}</button>;
  }
}

In functional components: you use the useState hook to handle state.

import { useState } from 'react';

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

  return <button onClick={() => setCount(count + 1)}>Count: {count}</button>;
};

🔄 Lifecycle Methods vs useEffect

In class components, you manage side effects with lifecycle methods like componentDidMount(). In functional components, the useEffect hook replaces this behavior.

// Class component
componentDidMount() {
  console.log("Component mounted");
}

// Functional component
useEffect(() => {
  console.log("Component mounted");
}, []);

⚙️ Key Differences at a Glance

🧰 Custom Hooks in Functional Components

One powerful benefit of functional components is the ability to write and use custom hooks. These are reusable functions that encapsulate logic across components.

import { useEffect } from 'react';

function useDocumentTitle(title) {
  useEffect(() => {
    document.title = title;
  }, [title]);
}

This level of reusability was much harder with class components, which lacked a simple way to share logic.

🚀 Performance Comparison

There’s no major performance difference between functional and class components. However, functional components may feel faster in development due to their cleaner structure and shorter syntax. With features like React.memo, useCallback, and useMemo, functional components can be just as optimized as their class-based counterparts.

📌 Final Thoughts: Which Should You Use?

If you’re starting a new project — use functional components.

They’re easier to work with, require less code, and offer powerful tools like hooks. Class components still work and are useful in older codebases, but for modern development, functional is the way forward.

✅ Quick Summary

• Functional Components: Lightweight, modern, hook-powered.
• Class Components: Verbose, still valid, but slowly becoming legacy.
• Use Hooks: For state, side effects, and shared logic in functional components.

Mastering both helps you navigate legacy and modern React codebases, but learning functional components and hooks is the key to being a productive React developer in 2025 and beyond.