Class Components vs Functional Components in React

💡 Class Components vs Functional Components in React

In React, we can use both functional components and class components.

Nowadays, almost everyone prefers functional components because they are simpler and have a more elegant syntax. However, there are situations where we might need to use the "old" class components.

Both approaches have their advantages and disadvantages, and the choice depends on the specific use case and your preferences as a developer.

In this article, we’ll explore the differences between these two methods of creating components in React and discuss how they affect state management, syntax, code readability, and other aspects.

If you're just starting out, feel free to check out my category on getting started with programming.

What is a Component in React?

In React, components are the building blocks of an application. Each component represents a piece of the user interface that can be reused in different parts of the application.

Components can accept data in the form of props and have state, which allows them to render interactive elements.

React allows us to create both functional and class components, and each approach has its unique characteristics.

⚡️ Functional Components in React – Quick Start

Functional components are a simpler way to create components. These are simply JavaScript functions that return JSX (a syntax similar to HTML used to define the appearance of elements in React).

Example of a Functional Component:

function SimpleComponent() {
  return <h1>Welcome to React!</h1>;
}

This component is simple – it doesn’t manage any state or use additional tools like hooks. If you want to learn more about hooks, check out my article on useEffect in React.

🛠 Hooks in Functional Components

Hooks are one of the most important features introduced in React. They allow us to add functionalities such as state management and side effects, which were previously only possible in class components.

Example using the useState hook:

import React, { useState } from "react";

function Counter() {
  const [counter, setCounter] = useState(0);

  return (
    <div>
      <p>Current count: {counter}</p>
      <button onClick={() => setCounter(counter + 1)}>Increase counter</button>
    </div>
  );
}

In the example above, we use the useState hook to manage the counter state in a functional component. Hooks allow for simple and concise state management without the need for classes.

🎯 Advantages of Functional Components

• Simplicity – Functional components are easier to write and more readable.
• Less code – They typically require less code than class components.
• Hooks – You can manage state and side effects without creating classes.
• Easier to test – Functional components are usually easier to test.

Class Components in React – The Traditional Method

Before hooks were introduced, the primary way to manage state in React was through class components.

A class component is a JavaScript class that extends React.Component and must have a render() method that returns JSX.

Example of a Class Component:

import React, { Component } from "react";

class ClassComponent extends Component {
  constructor(props) {
    super(props);
    this.state = {
      counter: 0,
    };
  }

  render() {
    return (
      <div>
        <p>Current count: {this.state.counter}</p>
        <button
          onClick={() => this.setState({ counter: this.state.counter + 1 })}
        >
          Increase counter
        </button>
      </div>
    );
  }
}

export default ClassComponent;

🔄 Key Differences Between Functional and Class Components

1. Syntax

Functional components use simpler syntax – they are regular functions that return JSX. Class components, on the other hand, must extend React.Component and use a more complex structure, which makes them less concise.

2. State Management

In functional components, we use hooks like useState to manage state, whereas class components use this.state and the setState method.

3. Lifecycle Methods

Class components have access to lifecycle methods such as componentDidMount, componentDidUpdate, and componentWillUnmount.

Functional components don’t have these methods but can use the useEffect hook, which serves a similar purpose.

4. Modernity and Popularity

Since the introduction of hooks in React 16.8, functional components have become the standard in most new projects, primarily due to their simplicity and flexibility.

React Hooks – Revolution in Functional Components

React Hooks are one of the most significant improvements in the React ecosystem.

They allow us to use functionalities in functional components that were previously only available in class components.

If you’re interested in learning more about hooks, check out my article on hooks in React.

The most important hooks are:

• useState – for managing state.
• useEffect – for handling side effects.
• useContext – for managing application context.

🎯 When to Use Functional Components vs Class Components

Functional Components:

• Ideal for simple components that don’t require advanced state management.
• When combined with React Hooks, they can fully replace class components.
• State management and side effects can be handled with useState and useEffect.

Class Components:

• Useful if you're using older versions of React, where hooks aren’t available.
• If you need to use lifecycle methods in a more traditional way, a class component might be a better choice.

📋Summary – Functional vs Class Components in React

Both functional and class components have their place in the React ecosystem, but since the introduction of React Hooks, functional components have become the preferred choice in most projects.

With hooks, functional components are more flexible, easier to write, and more readable.

If you're just starting with React, it's worth focusing on learning functional components and hooks.

Learn more about programming in my article on how to start programming from scratch.