ReactJS Components

In this tutorial, we'll explore the fundamental building blocks of React applications. Components are at the core of React development and understanding their different types, rendering methods, composition, and working with props is essential for building powerful and reusable user interfaces.

React components are designed to be reusable and modular, which means you can create components once and use them multiple times throughout your application. This promotes code reusability, reduces redundancy, and makes your codebase more maintainable.

You can include specific functionality or UI elements into individual components, making it easier to understand, test, and modify them independently.

Let's take a look at each aspect of React components step by step.

1. Functional Components

Functional components, also known as stateless components, are JavaScript functions that return JSX elements. They are the simplest form of components and are primarily used for presentational purposes.

In the above code, we define a functional component called Greeting that accepts a props parameter and returns a JSX element representing a greeting message.

2. Class Components

Class components are also known as stateful components. They are ES6 classes that extend the React.Component base class. They provide additional features like local state management and lifecycle methods.

In this code, we define a class component called Counter that initializes its state in the constructor and renders the current count value.

3. Rendering Components

To render a component, we can use JSX syntax within another component's render method or directly within the ReactDOM rendering function.

In the above code, we render the Greeting and Counter components inside a parent div element, and then we mount the entire component tree to the DOM root element.

4. Composing Components

One of the key advantages of React is component composition. It allows you to build complex user interfaces by combining and nesting components.

In this code, we create an App component that serves as the top-level component. It composes other components like Header, Content, and Footer to create the complete application UI.

5. Extracting Components

As your application grows, it's essential to extract reusable components to improve code organization and maintainability. Extracting components involves identifying reusable UI elements and creating separate components for them.

In this code, we extract a Card component that represents a reusable card element with a title and content.

6. Working with Props

Props (short for properties) allow you to pass data from a parent component to its child components. They are read-only and provide a way to customize and configure components dynamically.

In this code, the Product component receives name and price props, which are then used to display the product's name and price.

By leveraging these concepts effectively, you can create modular, reusable, and dynamic user interfaces that power your React applications.

In the next sections of this tutorial, we'll explore more advanced topics and techniques to take your React component skills to the next level.


React components are reusable and independent building blocks that encapsulate a piece of UI functionality. They allow you to split your user interface into smaller, modular parts, making it easier to manage and maintain your codebase. Components promote reusability, improve code organization, and enhance the overall development process. By composing components together, you can create complex and interactive user interfaces in a structured and efficient manner.

To create a React component, you can define a JavaScript function or a class. Function components are simpler and easier to write, while class components provide additional features like state and lifecycle methods. Here's an example of a function component:

import React from 'react';

function MyComponent() {
  return <div>Hello, React Component!</div>;

And here's an example of a class component:

import React, { Component } from 'react';

class MyComponent extends Component {
  render() {
    return <div>Hello, React Component!</div>;

Both function and class components can receive properties (props) as input and return JSX elements to define the component's UI.

React components are designed for reusability. You can reuse a component by importing it into other parts of your application and rendering it wherever needed. Components can also accept props, which allow you to customize their behavior and appearance based on different data or configurations. By passing different props to the same component, you can reuse it in various contexts while maintaining its core functionality. Additionally, you can create higher-order components (HOCs) or use component composition techniques to further enhance reusability and create more advanced component patterns.