Compiled Chronicles

A software development blog by Angelo Villegas

Component-Oriented Programming with React

With the rise of JavaScript frameworks, a newer design pattern is becoming popular. React, a JavaScript library, serves as an excellent example of Component-Oriented Programming principles in action. In this article, we’ll delve into the concept of COP, its relevance, and how React embodies its principles.

Understanding Component-Oriented Programming (COP)

What is Component-Oriented Programming?

Component-Oriented Programming (COP) is a programming paradigm that focuses on creating software systems by organising functionality into reusable and interchangeable components. These components encapsulate specific features, behaviours, or interfaces and can be combined to build complex applications.

Principles of Component-Oriented Programming

  1. Composition: Components are built through composition, where smaller specialised components are combined to create larger, more complex ones. This also means that components written by different people should work well when pieced together. This approach enables developers to create a library of reusable components, each responsible for a specific functionality or UI element. Emphasis on organising software systems in hierarchical structure, assembling components in a way that allows for easy composition and nesting.
  2. Abstraction: Abstraction involves abstracting the implementation details within components and exposing only the necessary interface. This abstraction shields the internal complexities, allowing components to interact based on well-defined interfaces. It also encourages modularity by breaking down complex systems into smaller components. Each component focuses on a specific task or feature, abstracting away unnecessary details, and offering a clear interface for interaction.
  3. Interoperability: Components are designed to work together seamlessly, emphasising interoperability. These components should communicate effectively, exchange data, and function cohesively within the system. Interoperability allows different components to collaborate without relying on implementation details, promoting flexibility and easy integration.

React — A Component-Oriented Library

React is a JavaScript library developed by Facebook that follows the principles of component-based development. It allows developers to build user interfaces by breaking them down into reusable components. React’s key feature is the use of a virtual Document Object Model (DOM), which enhances performance by minimising direct manipulation of the actual DOM.

Here’s a basic example of React utilising Component-Oriented Programming:

import React, { Component } from 'react'

// Function component
const Header = () => {
    return <h1>Welcome to Component-Oriented Programming!</h1>

// Class component
class Counter extends Component {
    constructor(props) {
        this.state = { count: 0 }

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

    decrement = () => {
        this.setState({ count: this.state.count - 1 })

    render() {
        return (
                <h2>Counter: { this.state.count }</h2>
                    <button onClick={ this.increment }>Increment</button>
                    <button onClick={ this.decrement }>Decrement</button>

class App extends Component {
    render() {
        return (
                <Header />
                <Counter />

export default App

The code demonstrates the use of Component-Oriented Programming in React. The Header is a function component that simply display a welcome message. The Counter is a class component that manages a counter state and includes functions to increment and decrement the count. The App serves as the parent component, utilising both the Header and Counter components.

Component-Oriented Programming in React involves creating modular and reusable components, allowing for better code organisation and maintainability.

How React Implements Component-Oriented Programming

  1. Component-Based Architecture: React applications are structured as a tree of components. Each component represents a part of the UI and is composed of its logic and UI elements. These components can be reused, composed, and nested within other components, promoting a modular approach to development.
  2. Reusability: React’s component-based structure promotes reusability. Developers can create components for specific UI elements, such as buttons, forms, headers, etc., and reuse them across multiple parts of the application. This is significantly reduces code duplication and speeds up developments.
  3. Abstraction: React encourages abstraction through component encapsulation. Each React components encapsulates its logic, state, and UI, exposing only necessary interfaces to interact with other components. This abstraction enables developers to work with components without needing intricate knowledge of their internal workings.
  4. Interoperability: React promotes interoperability between components by defining clear interfaces through properties and state. Components can communicate with each other by passing data through props or context, fostering seamless interaction and collaboration without direct dependencies.
  5. Interchangeability: React components are designed to be easily swappable. If a component needs to be replaced or upgraded, developers can do so without impacting other parts of application, as long as the interface remains consistent.

Benefits of Using Component-Oriented Programming in React

Improved Maintainability

By breaking down the application into smaller, reusable components, React facilitates easier maintenance. Changes or updates can be made to individual components without affecting the entire application, leading to better code maintenance.

Code Reusability and Scalability

With React’s component-based architecture, developers can create a library of reusable components. These components can be used across various projects, leading to faster development and scalability as the codebase grows.

Modular Development and Collaboration

Component-based development in React enables modular development, allowing teams to work on different components independently. This promotes collaboration and parallel development, as each team can focus on specific components without interfering with others.

Enhanced User Experience

React’s efficient rendering through the virtual DOM results in better performance. As only the necessary components are updated when there’s a change in state, React ensures a smoother user experience with faster rendering.

Best Practices for Component-Oriented Programming in React

  1. Single Responsibility Principle (SRP): Each React component should have a single responsibility, focusing on a specific part of the UI or functionality.
  2. Container and Presentational Components: Follow the pattern of separating container components (handling of data logic) from presentational components (dealing with UI rendering) for better maintainability.
  3. State Management: Use state management libraries like React Context API for centralised state management, especially in larger applications to maintain a clean and predictable state.
  4. Component Lifecycle: Understand and utilise React’s component lifecycle methods to manage behaviour efficiently.


Component-Oriented Programming, exemplified in React’s component-based architecture, offers numerous advantages in front-end development. By focusing on composition, reusability, abstraction, and interoperability, React allows developers to build scalable maintainable, and efficient applications. Embracing the principles of Component-Oriented Programming not only enhances the development process but also leads to improved user experiences and codebase sustainability in the long run.


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