Composition vs Inheritance in React

Software design pattern.

In this unit, we will explore two fundamental concepts in React: Composition and Inheritance. Understanding these concepts is crucial for structuring your React applications effectively.

Understanding the Difference Between Composition and Inheritance

In object-oriented programming, inheritance is a way to form new classes using classes that have already been defined. The new classes, known as derived classes, inherit attributes and behavior of the pre-existing classes, which are referred to as base classes.

On the other hand, composition is a way to combine simple objects or components to build more complex ones. In React, components can be used in their output, and this is referred to as "composition."

Why React Prefers Composition Over Inheritance

React has a powerful composition model, and it is recommended to use composition instead of inheritance to reuse code between components. In React, props and composition give you all the flexibility you need to customize a component's look and behavior.

Implementing Composition in React

In React, composition is implemented by using components as children in their output. This is done by placing the components within the opening and closing tags of the parent component.

Here is a simple example:

function WelcomeDialog() {
  return (
    <Dialog
      title="Welcome"
      message="Thank you for visiting our website!" />
  );
}

In this example, Dialog is a composited component, which can be reused in different parts of the application.

Use Cases for Composition and Inheritance in React

While React recommends composition over inheritance, there are use cases where inheritance makes sense. For example, when creating a hierarchy of classes that model a "is-a" relationship (e.g., a Dog is a Animal), inheritance can be a good choice.

However, in most cases, especially when dealing with UI, composition tends to be a better option. It allows you to keep components simple and reuse them in a flexible way.

In conclusion, understanding composition and inheritance in React is crucial for structuring your applications effectively. While React prefers composition over inheritance, understanding when to use each can help you make better design decisions when building your applications.