Higher Order Components (HOCs) in React: A Beginner’s Guide

Are you a React developer facing difficulty with code duplication and management of complex functionality across multiple components? As applications grow, you may find yourself repeating logic in different elements, leading to a messy codebase that’s hard to handle. This is where Higher-Order Components in React help you. It's a powerful solution that enables you to sum up code, use React Props and reuse logic seamlessly.   

This blog discusses Higher-order Components in React, including its structure, benefits, and some helpful examples.  

Table of Contents  

1) Understanding Higher-order Components (HOCs)  

2) Structure of Higher-order Components    

3) Appropriate Scenarios for Using HOCs in React  

4) How to Develop Higher-order Components in React? 

5) Benefits of Using Higher-order Components in React   

6) Practical Example of a Higher-order Component   

7) Approaches to Higher-order Components  

8) Conclusion  

Understanding Higher-order Components (HOCs)  

Higher-order Components is a robust design technique in React that improves components with extra features. These are functions that accept a component as input and produce a new component with added features, while leaving the original component unchanged. This fosters the reutilisation of code, streamlines intricate logic, and promotes the separations of concerns, leading to a more manageable codebase.   

Higher-order Components are especially beneficial in cases where various components require the same functionality, like dealing with authentication, state management, or enhancing performance. By using a Higher-order Components, developers can avoid repeating code by sharing and reusing logic.   

One typical example of an HOC is when it includes authentication in various components, ensuring that users are authenticated prior to using specific functionalities. In short, HOCs offer an orderly and effective method to expand component features while also maintaining the modularity and manageability of React applications.
 

Structure of Higher-order Components  

The way Higher-Order Components (HOCs) are designed in React enables developers to improve components by surrounding them with extra logic and characteristics. This methodical approach encourages the reuse of code and simplifies the design of complex applications.   

Let's understand the structure step-by-step:  

Step 1: It involves defining the Higher-Order Component (HOC) as a function that accepts a component as its input and then produces a new component with improved functionality.
 

Step 2: It involves establishing a class component to serve as the new component, encompassing the 'WrappedComponent' and incorporating any essential features.
 

Step 3: Make sure to pass all props, even those added by the Higher-order Component, to the 'WrappedComponent' in the 'render ()' function of the new component.
 

Step 4: Wrap up the Higher Order Component by sending back the 'new component' for smooth integration into the application.
 

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Appropriate Scenarios for Using HOCs in React  

Higher-order Components in React are perfect for scenarios where you need to reuse component logic, handle cross-cutting concerns, or improve multiple components without duplicating code.
 

1) Authentication  

In a program containing various paths, certain ones may need user validation. Instead of repeating the authentication logic for every route or component, you can establish a HOC named 'withAuth'. This Higher-order Component verifies user authentication and, if not authenticated, directs them to the login page. Using 'withAuth' to wrap elements or paths that require authentication ensures uniform functionality and decreases repetition in the code.  

2) Logging  

Instead of adding logging logic to individual components, you can create a HOC named 'withLogger' to log data when specific components mount or update. Using 'withLogger' surrounds the essential parts of logging consistently and effectively throughout those parts.  

3) Styling and Theming  

In a design system with reusable styles and themes, you can create a HOC called ‘withTheme’ to provide theme-related props to a component. This allows the wrapped component to be easily accessed and the correct styles to be applied according to the given theme. 

How to Develop Higher-order Components in React? 

Here’s how you can create a Higher-order Components in React: 

Step 1: Set up the React Project
 

Step 2: Move it using the given below command upon creation of project folder
 

Example:   

Benefits of Using Higher-order Components in React 

Higher-Order Components in React offer several benefits which are as follows:
 

a) Reusability: Higher-order Components allow for component logic to be reused in multiple components, which helps prevent code duplication and saves time during development. 

b) Versatility: HOCs can take on extra parameters, enabling customisation of their functions and transforming them into a versatile resource for enhancing components. 

c) Separation of Concerns: HOCs aid in preserving clear separation of concerns by isolating specific functionality in a distinct component, leading to improved code readability and maintainability. 

d) Composition: Combining HOCs enables developers to construct advanced features by using smaller, reusable components. 

e) Applications: Using a Higher-order Component is perfect for incorporating overarching concerns such as authentication, error handling, logging, performance tracking, and other key functionalities into your application. 

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Practical Example of a Higher-order Component 

Here’s an example of HOC in React for managing authentication:

How Does it Work? 

a) 'withAuth' is the Higher-order Component that verifies if the user is authenticated. 

b) If the user is not signed in, they are redirected to the login page 

c) When verified, it displays the 'Dashboard' component with all of its attributes 

d) By using 'withAuth' to wrap the 'Dashboard' and other components, you can protect them and grant only authenticated users to access them. 

Approaches to Higher-order Components 

HOCs can be applied by passing the original component as a parameter or using the "Render Props" approach. The selection depends on the use case and personal preference, with each having its advantages and disadvantages. Let's discuss them. 

1) Passing the Original Component as a Parameter 

In this method, a Higher-order Component (HOC) is a function that receives an existing component (the "wrapped component") as input and produces a new component with improved capabilities. The Higher-order Component (HOC) handles extra logic and transfers required props to the component it wraps. This technique enables you to efficiently use the same logic in multiple components without having to alter the original component directly. 

Example:
 

2) Render Props Method 

The method of Render Props includes sending a function as a prop to a component. Instead of enclosing a component with HOCs, the component is passed a function that dynamically dictates the rendering. This enables greater flexibility by allowing the component to determine its displayed content and behaviour according to its state or logic.

Example:

Conclusion 

Higher-order Components are crucial in React development as they allow for reusable logic, increased flexibility, and the promotion of clean code by separating concerns. They make complex functionality easier to manage, increasing codebase maintainability and modularity. Despite React developments, hooks have become more popular for simplifying similar tasks. If you want to elevate your development expertise, HOCs are the way to go.  

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