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Hooks in React JS: Everything You Need to Know

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19th Feb, 2023
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Hooks in React JS: Everything You Need to Know

Hooks in react js offer brand-new ways to build functional components, allowing us to integrate features like stateful logic that are only possible with class components. Hooks simplify using React.js and make it more straightforward by eliminating the requirement for class components and render methods and allowing us to utilize functions as hooks in their place. React version 16.7, published at the end of 2018, saw their announcement, and version 16.8, released in March 2019, saw their official release.

The class system is replaced by react js hooks. We may avoid needless abstraction and give a different method of managing stateful functionality without the need for inheritance or higher-order components using this alternate approach to React’s component architecture (HOC). They enable developers to access state and other React features without establishing a class, which was previously the only option.

This blog will take you through the most important sections you need to know to use hooks in react js effectively.

Guidelines for utilizing hooks

Although hooks are similar to the functions of JavaScript, several guidelines must be observed when utilizing hooks in react js. These guidelines make sure that the source code demonstrates all of the component logic.

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Call hooks exclusively at the uppermost level. This implies that hooks should only be invoked in React functions and never in a loop, condition, or even nested function. Every time it is rendered, this preserves the order of the components.

Use only ReactJS functions to invoke hooks; normal JavaScript functions cannot call hooks; only ReactJS function components can. Custom hooks are another name for reactjs hooks.

Prerequisites for using Hooks

The following are some requirements for using hooks in react js.

  • The Npm version should be at least 5.2
  • The node version should be at least 6.
  • For operating the ReactApp, the Create-react-app tool is required

Benefits of using ReactHooks in JS

The following are the benefits of using reactjs hooks– 

  • Simple to understand complicated components

In the past, the developers maintained components that began off easy but soon became stateful logic that was unmanageable. Errors and inconsistent data were commonplace as a result. Hooks let you break a single component into distinct functions depending on how its constituent pieces are connected, as opposed to needing a split based on lifecycle methods.

  • Simple to re-use Stated Logic

Hooks may be used to detach stateful functionality from a component so that it can be tested separately and re-used. These help us re-use the stateful logic without changing the component structure, which was previously challenging, even for higher-order components.

  • Reduced Complexity (with Functions!) without Classes

Because of courses, learning React might be challenging. Props, state, and the downward data flow are ideas that individuals understand intuitively but struggle to master in class. Even among experienced React developers, disagreements concerning the difference between function and class components are common.

Hooks, on the other hand, enable you to embrace functions and leverage additional React features without having to master complex functional or reactive programming approaches.

Type of Hooks in React js

The common type of reactjs hooks are built-in Hooks and Custom Hooks.

1. Built-in hooks

React contains built-in hooks, such as useEffect and useState, that allow developers to handle events or data updates with code snippets.

However, you may re-use stateful behavior across components using custom hooks. Let’s learn more about these built-in hooks first.

It is divided into two parts, i.e., the basic react js hooks and the additional hooks. The same has been given below-

Basic Hooks-

The following are the basic hooks-

  • useState
  • useEffect
  • useContext

Additional Hooks-

The following are the additional hooks-

  • useMemo
  • useReducer
  • useLayoutEffect
  • useDebugValue
  • useCallback
  • useRef
  • useImperativeHandle

Some of the reactjs hooks mentioned above have been described below-

2. useState Hook

The useState hook is used to save a component’s state.

You may use the useState hook to save and retrieve the state within a component without using this.state or this.setState (). The state object may be sent from the parent component to the child component through props or set directly on the child component using the useState hook.

3. useEffect Hook

We utilize the useEffect hook to do side effects like retrieving data from an API or saving it locally.

It allows function components to do side effects, achieving the same result as componentWillUnmount, componentDidMount, and componentDidUpdate, in React classes, but with a single API.

4. useRef Hook

Refs are a unique feature available on all React components. They enable us to generate a reference to a certain element or component when it mounts.

useRef makes it simple to use React references. They are useful when we wish to interact directly with an element, such as clearing its value or focusing it, as with an input.

To refer to it, we call useRef (at the top of a component) and attach the returned value to the element’s ref property.

5. useContext Hook

We wish to avoid the difficulty of providing several props to convey data down two or more layers from a parent component in React.

It is OK in some circumstances to transmit props across several components. However, passing props via components that do not require them is unnecessary.

Context is useful for transferring props from a parent component down several layers of child components and exchanging states throughout our app component tree.

The useContext hook eliminates the unusual-looking render props pattern that was previously necessary when using React Context.

Instead, useContext provides us with a simple method to retrieve the data we gave on the Context Provider’s value parameter in any child component.

6. useCallback Hook

useCallback is a hook that we use to improve the performance of our components.

Callback functions refer to certain functions that are called back within a parent component.

The most typical scenario is that you have a parent component with a state variable that you wish to update from a child component.

The parent passes a callback function to the kid. This allows us to update the parent component’s state.

useCallback memoizes our callback routines, preventing them from being regenerated on each re-render. The right usage of useCallback can increase the speed of our app.

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7. useMemo Hook

useMemo is similar to useCallback in a manner that it improves performance. However, instead of being used for callbacks, it is used to store the results of costly operations.

useMemo enables us to memoize or recall the outcome of costly operations that have previously been performed for certain inputs.

Memorization indicates that if a calculation has been performed previously with a specific input, there is no need to repeat it because the result of that operation has already been saved.

useMemo returns the computed value, which is subsequently saved in a variable.

8. useReducer Hook

useReducer, like useState, is a hook for state management that relies on a function called a reducer.

Reducers are pure functions that accept a prior state object and an action object and return a new state object.

useReducer is similar to useState in many aspects, but it is more useful for maintaining state across several components that may entail distinct operations or “actions.”

Around your app, you should utilize useReducer less than useState. However, it is extremely useful as a strong way of maintaining the state in smaller apps rather than relying on a third-party state management framework like Redux.

9. Custom Hook

A custom Hook is nothing more than a JavaScript function. This type of hook starts with use. This is used to show that the function will follow the rules of the Hooks. This hook’s running is equal to the standard function. Furthermore, creating custom Hooks allows you to separate component logic into reusable methods.

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Reactjs hooks, in a nutshell, have substantially expanded our capacity to create versatile React apps while decreasing the requirement for class-based components. React also includes some more hooks that you may utilize to improve the functionality of existing hooks and create even more amazing hooks on your own. We hope this blog helped you to understand what ReactHooks are. 


Pavan Vadapalli

Blog Author
Director of Engineering @ upGrad. Motivated to leverage technology to solve problems. Seasoned leader for startups and fast moving orgs. Working on solving problems of scale and long term technology strategy.
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Frequently Asked Questions (FAQs)

1What are the Prerequisites for react js hooks?

The following are some requirements for hooks. The Npm version should be at least 5.2 The node version should be at least 6. For running the ReactApp, the Create-react-app tool is required

2What are the types of Reacthooks?

There are two types of Reacthooks- built-in hooks and customs hooks. The built-in hooks are further divided into two, i.e., the basic hooks and additional hooks.

3What are the guidelines for using ReactHooks?

The guidelines for using ReactHooks are: a)Call hooks exclusively at the top level. This implies that hooks should only be invoked in React functions and never in a loop, condition, or even nested function. Every time it is rendered, this preserves the order of the components. b) Use only ReactJS functions to invoke hooks; normal JavaScript functions cannot call hooks; only ReactJS function components can. Custom hooks are another name for react hooks.

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