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Hooks in React –Benefits, Rules, Effects, Types, and Installation

Shailendra Chauhan  Print   33 min read  
22 Jul 2021
 
Intermediate
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Hooks are known to be one of the latest features implemented in the React 16.8 version. It lets you use the state and other React features in which you need to write a class. In simple terms, Hooks are the functions that connect React state and lifecycle features from the function components. Keep in mind that Hooks does not work within classes. 

Since Hooks are backward-compatible, it does not include any breaking changes. Moreover, it does not substitute your acquaintance with React concepts. All React js training courses may not teach you Hooks and their concepts. When you aim to Learn Reactjs Step By Step, it is necessary to learn Hooks and their advantages. 

To get more details on Hooks in React, you can know its benefits, effects, when to use them, and installation. So, take a look below:

Global state management with React Hooks | by Jhonny Michel | Noteworthy - The Journal Blog

What are the benefits of using Hooks?

For React developers, Hooks convey ample benefits as follows:

  • It revolutionizes the way you write components

  • You can write concise and clearer code.

  • Hooks are simpler to work with and test. Code would appear cleaner and easier to read.

  • A related logic could be tightly coupled inside a custom hook

  • It simplifies how to make code more composable and reusable. 

  • Unlike HOCs, they don’t create another element in DOM.

  • Hooks would work more efficiently with the future React optimizations. For example, it would work ahead of time compilation as well as components folding.

  • Components folding may be implemented in the future. It suggests that for code elimination at compile-time, hooks are simple to reuse the stateful logic.

Rules for using Hooks:

Before creating Hooks in React, you need to follow some rules, else you will face troubles later on. These rules make sure all the stateful logic within a component is visible inside its source code. Though these rules may not be mentioned in the React tutorial, it is better to get familiar with them beforehand. Here are the Hook rules:

1#. Call Hooks at the top level only:

Make sure not to call Hooks within loops, nested functions, or conditions. It is important to note that Hooks must always be utilized at the superior level of the React functions. It suggests that Hooks are invoked in the same order every time a component is rendered.

2#. Call Hooks from React functions only:

It is not allowed to call Hooks from standard JavaScript functions. The alternative is you can call Hooks from React function components. It is allowed to call Hooks from custom Hooks.

3#. When can you use Hooks?

When you write a function component, you would wish to add some state to it. Formerly, this was possible by converting it to a class. Now you can do that with the help of Hooks within the existing function component. After you know the appropriate usage of Hooks, it becomes easy to understand the Hooks concept in the react learning path.

Hooks Effect:

The Effect Hook enables you to accomplish side effects i.e. an action within the function components. Those components' lifecycle methods available within class components are not used in Hooks Effect. In simple terms, Effects Hooks are correspondent to componentDidUpdate(), componentDidMount(),and componentWillUnmount() lifecycle methods. If you are preparing for React Interview Questions and Answers, you can expect questions on Hooks Effect.

The corresponding side effects have some common features that the majority of web applications should perform. They are:

  • Fetching as well as consuming data from a server API

  • Updating the DOM

  • Setting up a subscription, and more

Two types of side effects in React component are:

  1. Effects Without Cleanup

  2. Effects With Cleanup

i. Effects without Cleanup:

This side effect is used in useEffect that does not restrict the browser from updating the screen. Moreover, it enhances the responsiveness of the app. Some common examples of the effects without cleanup are network requests, manual DOM mutations, Logging, etc.

ii. Effects with Cleanup:

Certain Hooks effects need cleanup after updating the DOM. For instance, if you intend to set up a subscription to an external data source, you must clear up memory else there will be a memory leak problem. It is found that React carries out the cleanup of memory whenever the component is unmounted. But the effects run for every render method instead of any particular method. Thus, React would also clean up effects from the preceding render before executing the effects succeeding time.

Types of Hooks:

The most common types of Hooks are built-in Hooks and Custom Hooks.

Built-in Hooks:

The built-in Hooks are categorized into 2 parts as follows:

Basic Hooks:

  • useState

  • useContext

  • useEffect

Additional Hooks:

  • useReducer

  • useMemo

  • useCallback

  • useRef

  • useImperativeHandle

  • useDebugValue

  • useLayoutEffect

Custom Hooks:

A custom Hook is basically a JavaScript function. Its name begins with "use" that could invoke other Hooks. The working of a custom Hook is identical to a regular function. The "use" in the starting describes that this particular function conforms to the rules of Hooks. Moreover, building custom Hooks enables you to extract component logic inside reusable functions.

Before proceeding with the installation of Hooks, you need to know its pre-requisites as follows:

Pre-requisites for React Hooks:

  • Node version 6 or higher

  • NPM version 5.2 or higher

  • Create-react-app tool for operating the React App

Installation:

Run the below codes:

$ npm install react@16.8.0 --save  

$ npm install react-dom@16.8.0 --save  

The aforementioned command would install the latest React as well as React-DOM 16.8 version that support React Hooks. Confirm that the package.json file records the React as well as React-DOM dependencies as provided below:

"react": "^16.8.0",  

"react-dom": "^16.8.0",  

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