Composition vs Inheritance in ReactJS

Anton Ioffe - September 3rd 2023 - 15 minutes read


ReactJS, an acclaimed JavaScript library for building user interfaces, offers two key techniques for crafting code: inheritance and composition. Composition is a pattern where developers create complete or complex functions by combining simpler ones. On the other hand, inheritance is a mechanism where objects or classes can inherit properties and methods from another. These object-oriented programming (OOP) concepts are key in the creation of component hierarchies in ReactJS applications.

Understanding these mechanisms and knowing when to use each is crucial in maximizing the effectiveness of your ReactJS code. As we delve deeper into this topic, we'll discuss the nuances, strengths, and potential shortcomings of both composition and inheritance within the ReactJS ecosystem. This will help in deciding the best approach in crafting more efficient, readable, and reusable components in your journey to becoming a more proficient ReactJS developer.

Understanding Concepts: Inheritance and Composition in Programming

Understanding the fundamental concepts of inheritance and composition lays the groundwork for effective application in ReactJS. In this section, we'll delve deeper into these pivotal concepts, introducing you to relevant code examples and guiding you through the identification of common mistakes.

Inheritance characterizes a keystone of Object-Oriented Programming (OOP). It allows derived classes, or subclasses, to inherit properties and methods from base or parent classes, often referred to as superclasses. This concept mirrors real-world inheritance, where offspring may inherit traits from their parents. Hence, it fosters deep-seated code reusability.

JavaScript, fascinatingly, leverages a prototypal inheritance model where objects can inherit properties from other objects, referred to as prototypes. An intuitive way to visualize this model is to picture objects linked in a chain. Each object has a prototype (another object), and it can inherit properties from it. Let's proceed with a robust, commented example of inheritance using ES6 class syntax:

class Vehicle {
    constructor(name, type) { = name;
        this.type = type;

    // Description method of the Vehicle superclass
    description() {
        return `${} is a vehicle of type ${this.type}`;

// Car is a subclass extends from the Vehicle superclass
class Car extends Vehicle {
    constructor(name) {
        super(name, 'car');

    // Additional method specific to the Car class
    drive() {
        return `${} is driving!`;

// Instantiate a new Car class object
const myCar = new Car('Volkswagen');

// Call inherited and own method
console.log(myCar.description()); // Volkswagen is a vehicle of type car
console.log(; // Volkswagen is driving!

In this example, the Car subclass makes use of the description method inherited from the Vehicle superclass, an excellent instance of prototypal inheritance. However, keep in mind that a common pitfall involves wrongly using inheritance to share code, which results in an unnatural hierarchical relationship.

Unlike inheritance, composition provides an alternative approach, one that fosters code flexibility and modularity by enabling objects to be composed from one or more distinct objects. Composition revolves around the concept of a "has-a" relationship, representing a contrast to the "is-a" relationship inherent to inheritance. Let's delve into an annotated example of composition:

// Behavior that can be used in multiple objects
function canDrive({ name }) {
    return { drive: () => console.log(`${name} is driving!`) };

// Another behavior that can be used in different objects
function canFly({ name }) {
    return { fly: () => console.log(`${name} is flying!`) };

// Car factory function composes an object using canDrive behavior
function carFactory(name) {
    const spec = { name: name, type: 'car' };
    return Object.assign({}, canDrive(spec));

// Airplane factory function composes an object using canFly behavior
function airplaneFactory(name) {
    const spec = { name: name, type: 'airplane' };
    return Object.assign({}, canFly(spec));

// Creating objects using our factory functions
const carInstance = carFactory('Toyota');; // Toyota is driving!

const airplaneInstance = airplaneFactory('Boeing');; // Boeing is flying!

In this snippet, carFactory and airplaneFactory are objects composed from behaviors canDrive and canFly. However, overusing object composition can lead to finish up with small objects that together form hard-to-understand structures.

Deciding between inheritance and composition is context-dependent, tailored to your software design needs. Inheritance is beneficial for clearly delineated "is-a" relationships. In contrast, composition caters to complex functionalities by integrating simpler objects, fulfilling the principle of function composition: to build complex things by stitching together simple, smaller parts.

In the realm of ReactJS, which we will explore in following sections, composition is highly favored for its malleability and simplicity. Indeed, ReactJS's official documentation heralds composition over inheritance as a best practice.

Despite their individual merits, misuse of both inheritance and composition can trigger code complexities, including overly tight coupling, poor abstraction, as well as difficulty in debugging and testing. Successful navigation of these concepts necessitates rigorous technical comprehension and a solid grounding in software design principles and best practices.

Let's tease your intellect with a few questions: Were you intrigued by the way JavaScript handles inheritance and composition? Can you calibrate the drawbacks and benefits of employing either or both of these techniques in your project? Perhaps "What challenges could arise from choosing inheritance over composition? “Or "Could the choice between inheritance and composition sway code scalability in large-scale projects?" These stimulating queries are fundamental to an in-depth comprehension and efficient application of inheritance and composition as you map out your ReactJS journey.

Inheritance Vs Composition in ReactJS: Definitions, Uses, And Comparisons

Unravelling Inheritance and Composition in ReactJS might seem like a daunting task, but the beauty of these concepts lies in their practicality and the sheer ease that they bring to the realm of front-end development.

In ReactJS, inheritance and composition are fundamental methods of defining, creating, and utilizing components. While they do share these attributes, they offer distinct approaches, and understanding their relative strengths and weaknesses is crucial.

To start with, let's look at inheritance:

class ParentComponent extends React.Component {
    render() {
        return <h1>Welcome to Inheritance!</h1>

class ChildComponent extends ParentComponent {
    render() {
        return <p>Inheritance is at play!</p>

Here, the ChildComponent is inherited from the ParentComponent and can technically override its render method. This is a classic example of Inheritance and leads to a “is-a” relationship between components. While this might seem straightforward, overriding the render method in the child component might lead to code repetition and lack of reusability. This is one of the most common mistakes made while using inheritance.

Moving on, let's explore composition:

function ParentComponent(props) {
    return <div>{props.children}</div>

function ChildComponent() {
    return (
            <p>Composition in action!</p>

With composition, we pass components as props (children, in this case) to other components. In this sense, a ChildComponent “has-a” ParentComponent, a clear example of a Composition approach. With this approach, our code becomes more intuitive, as the relationship between the components is considerably clearer. It encourages code re-usability and modularity. However, an often-occurring mistake while using Composition is passing a large number of children or props leading to an increase in complexity which might affect performance.

How, then, do we decide when to use inheritance or composition? The answer mainly depends on the problem you are trying to solve. While inheritance might be a good match when there are clear "is-a" relationships between components, composition often proves to be more effective in providing reusability and maintainability. In fact, a widely accepted best practice within the ReactJS community is to prefer composition over inheritance, keeping your components small and focused on doing one thing well.

Are there scenarios in your projects where inheritance could have been replaced by composition for better code maintainability and readability? How about memory and performance? Did the choice between inheritance and composition affect them differently in your project? Reflecting on these questions will enable you to make more effective use of inheritance and composition in your ReactJS projects, leveraging their strengths and mitigating their weaknesses.

Practical Examples: Inheritance vs Composition in ReactJS

Let us dive deeper into the practical applications of Inheritance and Composition in ReactJS. We'll explore real-world examples and compare the benefits and drawbacks of each approach.

Understanding Inheritance in ReactJS

Inheritance is a core concept in object-oriented programming, but in the context of ReactJS, its usage often leads to high coupling and inflexibility. It's a practice often warned against in the React community, and for good reason, here's a classic example of Inheritance:

class Button extends React.Component {
  render() {
    return <button style={{backgroundColor: this.props.color}}>

class DangerButton extends Button {
  constructor(props) {
    this.props.color = 'red';

ReactDOM.render(<DangerButton>Hello World!</DangerButton>, document.getElementById('root'));

The danger here is that if the parent component changes in a way that doesn't align with the child component, we can run into all sorts of problems. If the Button was to remove the usage of this.props.color entirely, DangerButton would fail. That's our first common implementation mistake: making too many assumptions about the internals of parent components.

Transitioning to Composition in ReactJS

In contrast to inheritance, composition involves building complex components by piecing together simpler ones. It enables you to manage complexity, promote modularity and reusability. Here's the compositional approach to the previous example:

function DangerButton({ children }) {
  return <Button color='red'>{children}</Button>

ReactDOM.render(<DangerButton>Hello World!</DangerButton>, document.getElementById('root'));

By adopting this pattern, we gain a more flexible, modifiable, and easy-to-understand component system. A common mistake here can be overuse. Where there is a simple, straightforward option, it may be better to use single, uncomplicated components.

Impact of React’s Hooks and Context API on Composition

With the introduction of Hooks and the Context API in React, the emphasis on composition has increased, providing a more functional way of sharing state and behavior amongst components. Let's take an example of using Hooks with composition:

import React, { useState } from 'react';

function Button({ initialColor, children }) {
  const [color, setColor] = useState(initialColor);

  return <button
           style={{backgroundColor: color}} 
           onClick={() => setColor(color === 'red' ? 'blue' : 'red')}>

ReactDOM.render(<Button initialColor='red'>Hello World!</Button>, document.getElementById('root'));

With Hooks, we can isolate the state and logic inside one component, providing better reusability, testability, and separation of concerns.

A common mistake with Hooks is that you might feel the urge to create Hooks for everything. Remember that creating a Hook brings additional complexity, and it's usually a good idea only when you need to share logic across multiple components.

Finally, in most scenarios in React, composition will be your best friend due to its flexibility, reusability, and readability. As developers, our duty is not only to write working code, but understandable and maintainable code. By leaning on composition, we can achieve these goals more easily. Does your codebase favor composition or inheritance? What changes can you make today to leverage the power of composition?

Impact of React Hooks and Context on Composition

The evolution of ReactJS has heavily been impacted by two new inclusive elements – React Hooks and Context. Their introduction has not only streamlined the sharing and management of state, but also profoundly transformed how components are created and work together.

Taming Composition with React Hooks

React Hooks bring state, side-effects, context, and other React features into function components. These elements were once predominantly the domain of class components, requiring developers to grapple with the intricacies of Higher Order Components (HOCs) and Render Props, occasionally culminating in the infamous 'wrapper hell'. Hooks effectively address this issue, allowing encapsulation and sharing of stateful logic across components without restructuring the component drastically.

Consider we have a UserProfile function component that fetches user data from an API endpoint influenced by useState and useEffect hooks:

import React, { useState, useEffect } from 'react';

function UserProfile({ userId }) {
    // Using useState to define variable and its setter
    const [user, setUser] = useState(null);

    // Using useEffect to fetch user data when userId changes
    useEffect(() => {
            .then(response => response.json())
            .then(data => setUser(data));
    }, [userId]);

    if (user) {
        return (

    return null;

In the above code, we can see how Hooks facilitate cleaner composition by avoiding the need to wrap the component in Higher Order Components or add redundant lifecycle methods.

Revolutionizing Composition using Context

React Context provides an ideal way to share data across components, bypassing the need for explicit prop passing or 'prop drilling'. As an illustrative example, let's say we have a theme that we want to apply through our application. Traditionally, passing this theme prop through every component would seem burdensome, especially when our theme can change dynamically.

React Context solves this problem through creating a context that all child components can subscribe to, without being passed as a prop directly:

import React, { useState, useContext } from 'react';

// Declaring context
const ThemeContext = React.createContext();

// Using the Provider to make theme and setTheme available to all children
const App = () => {
    const [theme, setTheme] = useState('light');
    return (
        <ThemeContext.Provider value={{ 'theme': theme, 'setTheme': setTheme }}>
            <Header />
            <MainContent />

// Using context to consume the context value in a child
const Header = () => {
    const { theme, setTheme } = useContext(ThemeContext);
    return (
        <header className={`header ${theme}`} 
                onClick={() => setTheme(theme => theme === 'light' ? 'dark' : 'light')}>
            Switch Theme

// This example does not define the MainContent component but it would have access to ThemeContext as well.

The comparison of using hooks and context with inheritance is evident in our superior reliance on function components. This mutates JavaScript's native functional composition enhancing readability over the convoluted inheritance model. Nonetheless, remember that though hooks and context have transformed modern React development, class components still maintain their relevance.

Alright, let's talk potential concerns. When it comes to Hooks and Context, are you using a specific technique? Are you mindful of the potential downsides of heavy reliance on these tools? Ever stumbled upon typical missteps with Hooks and Context?

Let's discuss a common mistake related to Hooks - forgetting to list dependencies in array on useEffect Hook. Developer might choose to ignore listing all dependencies assuming it might not influence the final outcome, but this leads to inconsistent behavior since the effect will not update on changes:

// NOT optimal - missing dependency in the list
useEffect(() => {
        .then(response => response.json())
        .then(data => setUser(data));
}, []);  // an empty array means the effect runs only once

To fix this issue, always include all variables from the component's scope that change over time and are used in the effect:

// Optimized Version - Include all dependencies in the list
useEffect(() => {
        .then(response => response.json())
        .then(data => setUser(data));
}, [userId]);  

By keeping these scenarios and best practices in mind, your use of React Hooks and Context will be more effective and your code will stay clean and easy-to-understand! Do you have any practical experiences or questions related to what we just discussed?

Extending Functionality: Difficulty and Complexity of Adding New Behavior Via Inheritance Vs Composition in React

ReactJS, a popular JavaScript library for creating dynamic user interfaces, fosters an ecosystem that highly values composition over inheritance. That said, this doesn't entirely negate the use of inheritance as a method of extending functionality. In this deep-dive, we examine these two paradigms—composition and inheritance in ReactJS—evaluating their benefits, potential pitfalls, and their influence over our approach to integrating new functionalities.

Inheritance in ReactJS

Inheritance forms the base principle in many programming languages. Though ReactJS leans towards a function-based implementation with hooks, it does not eschew class-based inheritance. This is prevalent when working with class components, where developers create a superclass with its state and lifecycle methods, and then generate child classes based on this template.

Below is a simple demonstration of inheritance at work:

class ParentComponent extends React.Component {
    constructor(props) {
        this.state = { color: 'red' };

    colorChange() {
        // Change color behavior is defined here

class ChildComponent extends ParentComponent {
    // Inherits state and colorChange lifecycle method from ParentComponent

In the example above, ChildComponent inherits all properties and lifecycle methods from ParentComponent. A new lifecycle method or class member function can be swiftly integrated by adding it to the ParentComponent, making this method immediately available across all subclasses.

Common Mistakes and Problems with Inheritance

However, over-reliance on inheritance can lead to complex architectures and obfuscate component lifecycles. Some common pitfalls include over-engineering, where unnecessary hierarchies of components are created due to misuse, and the "Fragile Base Class" problem.

Fundamentally, the "Fragile Base Class" problem arises when a modification to the superclass inadvertently disrupts the subclass functionality. As an example, consider a scenario where the superclass introduces a new method already defined in its subclass, leading to unforeseen behaviors and elusive bugs.

It's crucial to be conscious of such potential issues when considering inheritance as a design strategy in your ReactJS applications.

Composition in ReactJS

In stark contrast to inheritance, composition allows the construction of larger components by combining smaller, reusable ones.

Here's an anecdotal demonstration of how composition works:

function ParentComponent() {
    const colorChange = () => { /* Altering color functionality goes here */ };
    return (
        <ChildComponent colorChange={colorChange} />

function ChildComponent(props) {
    // Accesses function from ParentComponent
    const { colorChange } = props;
    // ...more of the component

The ChildComponent doesn't inherit from ParentComponent. Instead, it accesses functionality through transferred props—a fundamental aspect of composition promoting a flat structure.

Common Mistakes and Problems with Composition

Nonetheless, composition is not without its pitfalls. Excessive use of composition can lead to a problem known as "props drilling", where properties traverse through many component layers, leading to bulkier and unwieldy code.

Moreover, applying too many Higher-Order Components (HOCs) can result in a situation colloquially referred to as "Wrapper Hell". This situation occurs when the code becomes overburdened with wrapped components, making it difficult to read, understand, and debug. Additionally, passing functions as props may cause unnecessary rerenders, thereby affecting the application's performance.

React Hooks and Context: Favoring Composition

The introduction of React Hooks and the Context API has further propelled the use of composition over inheritance. Hooks such as useState and useEffect have unshackled functional components from their previously limited ability to manage state and side-effects. The Context API strategically circumvents the infamous 'props drilling' problem by enabling a more direct state sharing among components.

A shift towards functional components and Hooks is an evident sign of React's preference for composition.

Optimizing for Performance, Readability, and Modularity

While React does champion composition, it's important not to discard the potential applicability of inheritance. While inheritance provides a structured hierarchy, it can introduce unnecessary complexity. On the other hand, composition's emphasis on modularity and reusability is often at the risk of excessive props drilling and potential clutter.

The challenge lies in striking a balanced approach when extending functionalities. Highlight factors such as complexity, performance, readability, and modularity in your application when deciding between inheritance and composition.

Lean towards composition, as it allows for tailored assembly of components, encapsulated component functionalities through state, and proficient state sharing via context. However, class components may be a preferable choice in some contexts.

Reflect on the challenges associated with managing class components in large React projects. Were there situations where composition's benefits overshadowed the complexity it introduced? How could React's advanced features like Hooks and Context API potentially resolve the issues you encountered? These questions could be instrumental in forming design decisions for the next React application you build.


We've journeyed through the intricate land of ReactJS, twining our way through complex mountains of inheritance and admiring the beautiful simplicity of composition. We've learned that inheritance is a concept used in class-based programming where one class can inherit methods and properties from another class. However, the react team recommends the use of composition, a model wherein components are built using smaller, reusable pieces, instead of inheritance. We've observed that with composition, you can create more flexible, comprehensible, and modular code, which is in better alignment with React's philosophy.

We’ve also unloaded hefty wagonloads of the pros, cons, practical use cases, and potential pitfalls of utilizing each approach in the wilderness of ReactJS. While inheritance can be powerful for reusing code across similar subclasses, it may lead to overcomplicated code structures and is less suited for ReactJS where functionality is best shared among unrelated components through composition. In the end, it is composition, the technique of breaking down complex components into smaller, easier-to-manage parts, that aligns better with React’s ethos of simplicity and reusability.

Now, a challenge for our intrepid readers: You are creating an entire library system for a university, where you’re tasked with developing interfaces for three roles- 'Admin', 'Librarian', and 'Student'. Each role has unique views, permissions, and actions. Sketched out in your mind, with endless possibilities of features, comes the challenge of striking an equilibrium between inheritance and composition. How do you propose to organize the components for these roles in the most efficient way? Remember to balance your approach, reflecting on everything you've learnt so far about these two unique paradigms in ReactJS. It's a test of everything you’ve learned in this article as well as an opportunity to delve deeper into the intricacies of composition and inheritance. Wishing you the best of luck in your coding adventures!

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