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React Components: Functional vs. Class

React components are the building blocks of modern user interfaces, enabling developers to create modular, reusable, and maintainable code. Each component contains reusable bits of code that return HTML and makes building user interfaces much easier for many reasons we'll explore shortly.

First, let's explore the two main types of React components and their usage in a development environment.

Component Types

Functional Components

Functional components are stateless components defined as JavaScript functions. They receive props (properties) as input and return JSX (JavaScript XML) to describe the UI. These types of components are simpler and easier to read and test.

Here's an example of a functional component:

function Hello(props) {
return <h1>Hi, {}!</h1>;

Class Components

Class components are stateful components that are defined as ECMAScript 6 (ES6) classes. They have an internal state object and can have lifecycle methods. Class components are useful when you need to perform complex logic or manage state, where the object can hold and manage dynamic bits of information over its lifetime.

Here's an example of a class component in action:

class Hello extends React.Component {
render() {
return <h1>Hi, {}!</h1>;

Rendering the Component Results

To render our newly created component in the application, we'll use the following syntax as a custom HTML pseudo-element:

import React from "react";
import ReactDOM from "react-dom/client";

const root = ReactDOM.createRoot(document.getElementById("root"));
root.render(<Hello name="Orangeable" />);

How Components Make Things Easier

  • Modularity: Components promote a modular approach to building user interfaces by breaking down the UI into smaller, self-contained components, each responsible for a specific functionality or part of the UI.
  • Reusability: Components are reusable, meaning you can use them throughout multiple parts of your code to return similar output depending on its defined props. Reusability saves time and effort by eliminating the need to rewrite the same code for similar UI elements and improves consistency across the application, giving it a more uniform look and feel.
  • Data Flow: React enforces a unidirectional data flow, meaning the data flows from parent components to their associated child components through props, making it easier to track and manage data changes.
  • Virtual DOM: React utilizes a virtual DOM (Document Object Model) to update the UI. When a component's state or props change, React calculates the minimum changes required to update the UI and applies them to the virtual DOM. This helps improve performance and reduces unnecessary re-rendering.


As you can see, React components offer a powerful way to build interactive and dynamic user interfaces. Whether you're developing simple UI elements or complex applications, understanding and harnessing the power of React components is key to unlocking the library's full potential.

Created: July 08, 2023


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