Introduction
In React, components are the building blocks of any application. There are two main types of components: functional components and class components. Knowing their differences helps you choose the right one for your project.
Functional Components
Functional components are JavaScript functions that return JSX. They are simpler to write and use. Before React Hooks were introduced, functional components could not have state or lifecycle methods. Now, with Hooks like useState and useEffect, they can do almost everything class components can.
Example
function Greeting(props) {
return <h1>Hello, {props.name}!</h1>;
}
- Written as plain JavaScript functions.
- Accept props as input and return JSX.
- Easier to read, maintain, and test.
- Great for simple, reusable UI elements.
- Hooks enable them to handle state and side effects.
Class Components
Class components are ES6 classes that extend from React. Component. They have more built-in features, such as state and lifecycle methods, without needing Hooks.
Example
class Greeting extends React.Component {
render() {
return <h1>Hello, {this.props.name}!</h1>;
}
}
- Written as ES6 classes.
- Must extend React.Component.
- Can store state directly using this. State.
- Have lifecycle methods like componentDidMount and componentDidUpdate.
- More verbose compared to functional components.
Comparison Table
| Feature |
Functional Components |
Class Components |
| Syntax |
Simple function |
ES6 class |
| State Management |
With Hooks |
Built into this.state |
| Lifecycle Methods |
With Hooks |
Direct methods available |
| Code Complexity |
Less |
More |
| Performance |
Slightly faster |
Slightly slower |
Summary
Functional components are lightweight, easy to write, and perfect for most modern React applications, especially with Hooks enabling state and lifecycle features. Class components, while more verbose, are still useful for certain legacy codebases and can manage complex logic without Hooks. Choosing between them depends on your project’s needs, but most new React development favors functional components for cleaner and more maintainable code.