Building a custom hook in React

A custom hook is a JavaScript function that starts with the word “use” and that can call other hooks. Here’s an example of a simple…

Building a custom hook in React

Having worked across sites raking in over 50 billion website visits annually with Higglo Digital. I write about tech topics and teach engineers to have solid foundations that will help them get ahead in their career. I also build awesome products for digital nomads — check it out!

JavaScript eBook

I’ve written an eBook on JavaScript that will take you from beginner to professional. Having been in your shoes moving to making over $200,000 per year in just a few years as a software engineer, I know exactly what it takes to get there. Check out the ebook now!

Custom hooks are a powerful part of React that lets you pull reusable logic out of your components and wrap it in a function that can be used again and again. Custom hooks can help improve the modularity and reuse of your code, and they can make it easier to share logic between different parts of your application. In this article, we’ll look at how to build a custom hook in React and discuss some best practices for using custom hooks in a React application.

Anatomy of a custom hook

A custom hook is a JavaScript function that starts with the word “use” and that can call other hooks. Here’s an example of a simple custom hook that tracks the mouse position:

import { useState, useEffect } from 'react';

const [position, setPosition] = useState({ x: 0, y: 0 });
 
function handleMouseMove(event) {
setPosition({

y: event.clientY javascript

window.removeEventListener('mousemove', handleMouseMove);

;

, []);

 
In this example, the custom `**useMousePosition**` hook uses the `**useState**`and `**useEffect**` hooks to track the mouse position and update the position state. The `**useEffect**` hook is used to add and remove a mousemove event listener to the window object, and the `**useState **`
#### Using a custom hook
 
To use a custom hook, you’ll need to import it into your component and call it like a regular function. Here’s an example of how to use the custom `**useMousePosition**` hook in a component: 
import { useMousePosition } from './useMousePosition';
 
```javascript
const position = useMousePosition();
return (
 }
 
In this example, the custom `**useMousePosition**` hook is imported into the `**MouseTracker**`
 
#### Best practices for building custom hooks in React
 
Here are a few best practices to keep in mind when building custom hooks in a React application:
 
- Follow the naming convention: It’s important to follow the naming convention for custom hooks, which is to prefix the hook name with “use”. This helps distinguish custom hooks from regular functions and makes it clear that the hook can be called from a component.
- Extract only pure logic: Custom hooks should only contain pure logic and should not have any UI or rendering logic. This helps ensure that the hook is reusable and can be used in different parts of the application.
- Test the hook: It’s important to test the custom hook to ensure that it’s working as expected and to catch any regressions or bugs early on. This can be done by manually testing the hook and by using tools like Jest and Enzyme to write unit tests for the hook.
- Document the hook: It’s important to document the custom hook to make it clear how it should be used and what it does. This can be done by adding a documentation comment at the top of the hook function and by adding examples of how to use the hook in the documentation.
 
In short, custom hooks are a powerful part of React that let you pull reusable logic out of your components and wrap it in a function that can be used again and again. By following best practices and using the right tools, you can build custom hooks that are modular, reusable, and easy to maintain.
 
#### JavaScript eBook
 
I’ve written an eBook on JavaScript that will take you from beginner to professional. Having been in your shoes moving to making over $200,000 per year in just a few years as a software engineer, I know exactly what it takes to get there. [Check out the ebook now](https://www.mitrakos.com/ebook)!
 
I founded [Higglo Digital](https://higglo.io/) and we can help your business crush the web game with an award-winning website and cutting-edge digital strategy. If you want to see a *beautifully designed website*, [check us out](https://higglo.io/).
 
I also created [Wanderlust](http://www.wanderlustapp.io/) to discover the most beautiful places across the world with highly curated content. Where do you want to travel to next?

In this example, the custom `**useMousePosition**` hook uses the `**useState**`and `**useEffect**` hooks to track the mouse position and update the position state. The `**useEffect**` hook is used to add and remove a mousemove event listener to the window object, and the `**useState **` #### Using a custom hook To use a custom hook, you’ll need to import it into your component and call it like a regular function. Here’s an example of how to use the custom `**useMousePosition**` hook in a component: import { useMousePosition } from './useMousePosition'; ```javascript const position = useMousePosition(); return ( } In this example, the custom `**useMousePosition**` hook is imported into the `**MouseTracker**` #### Best practices for building custom hooks in React Here are a few best practices to keep in mind when building custom hooks in a React application: - Follow the naming convention: It’s important to follow the naming convention for custom hooks, which is to prefix the hook name with “use”. This helps distinguish custom hooks from regular functions and makes it clear that the hook can be called from a component. - Extract only pure logic: Custom hooks should only contain pure logic and should not have any UI or rendering logic. This helps ensure that the hook is reusable and can be used in different parts of the application. - Test the hook: It’s important to test the custom hook to ensure that it’s working as expected and to catch any regressions or bugs early on. This can be done by manually testing the hook and by using tools like Jest and Enzyme to write unit tests for the hook. - Document the hook: It’s important to document the custom hook to make it clear how it should be used and what it does. This can be done by adding a documentation comment at the top of the hook function and by adding examples of how to use the hook in the documentation. In short, custom hooks are a powerful part of React that let you pull reusable logic out of your components and wrap it in a function that can be used again and again. By following best practices and using the right tools, you can build custom hooks that are modular, reusable, and easy to maintain. #### JavaScript eBook I’ve written an eBook on JavaScript that will take you from beginner to professional. Having been in your shoes moving to making over $200,000 per year in just a few years as a software engineer, I know exactly what it takes to get there. [Check out the ebook now](https://www.mitrakos.com/ebook)! I founded [Higglo Digital](https://higglo.io/) and we can help your business crush the web game with an award-winning website and cutting-edge digital strategy. If you want to see a *beautifully designed website*, [check us out](https://higglo.io/). I also created [Wanderlust](http://www.wanderlustapp.io/) to discover the most beautiful places across the world with highly curated content. Where do you want to travel to next?