Class Components and Functional Components in Reactjs

In this article, we will learn about class components and functional components. Also, learn about the difference between class and functional components....

Written by Rohit Sharma · 2 min read >

In this article, we will learn about class components and functional components. Also, learn about the difference between class and functional components.

How do React JS Components work?

A React component is a standalone, reusable chunk of code with specific functionality. Such elements work together to create a web application’s dynamic and user-friendly user interface (UI). To put it another way, components can be thought of as the building elements of the website or user interface that we are developing.
Thousands of lines of code would be required to put together a single file without the use of components. As the project expands, this makes the code more complex and requires more upkeep. Components are widely utilized to prevent all of this. The two basic categories of components are class-based or stateful and functional or stateless. The latter portion, which discusses React JS Class components in detail, will receive the majority of our attention.

What are Class Components?

Functional components are easier to construct than React JS Class components, which are ES6 classes. Constructors, life cycle methods, render functions, as well as state or data management, are all included in each React JS class. React JS classes must extend the Component in order to be used. Only React JS will then be able to recognize that this specific component is a class and will render or return the necessary react element.

Key characteristics of a React JS class

Let’s talk about the key characteristics that all React JS class components have now that we are aware of what classes are in React. Therefore, a React class component,

a) The ES6 class
b) Won’t become a component until it extends the React JS Component.
c) While using the constructor, can accept props.
d) Maintains its own data with state assistance
e) A render function that can only return a react element or null should always exist
f) Classes then control the component’s state
g) Through classes, one may add life cycle methods to the component


import React from "react";

class App extends React.Component {
constructor(props) {
	this.state = { change: true };
render() {
	return (
		<button onClick={() => {this.setState({ change: !this.state.change });
		Click Here!
		{this.state.change ? (
		<h1>Welcome to Let’s React</h1>
		) : (
		<h1>Learn about the concepts of Reactjs</h1>

export default App;

What are Functional Components?

Class components and functional components are the two primary categories of components used by programmers in React.js. Functional components use functions, whereas class components make use of ES6 classes. A functional component is just required to receive props as an argument and return a legitimate JSX. Class components, on the other hand, are required to use the render method. Like class components, functional components lack state and lifecycle functions. They are also referred to as stateless components for this reason.


import React, { useState } from 'react';
const Example=()=> {
  const [change, setChange] = useState(true);     
      return (
        <button onClick = {() => setChange(!change)}>
          Click Here!
        {change?<h1>Welcome to Let’s React</h1>:
                <h1>Learn about the concepts of Reactjs</h1>}
export default Example;

Why should you use functional components from React.js?

You must be asking how the absence of state-based and lifecycle methods is beneficial. Here are some of the main justifications for choosing functional components in React.js over classes:
a) Increases readability of code
b) Simple to test
c) Leads to better performance
d) It’s simple to do debugging
e) Coupling Factor Reduction

Difference between Class and Functional Components

A basic Javascript class that extends React. Component is called a class component. It contains a render method that is required, and inside of it, we must return the React element or JSX.A functional component is nothing more than a straightforward Javascript function that outputs a React element, or JSX.
The render method in-class component must be implemented.The functional component doesn’t apply a render mechanism.
They are also referred to as stateful components since they combine logic with state.They are also referred to as stateless components because they accept data and display it in a predetermined format.
The class components can use React lifecycle methods.The functional component cannot be used inside React lifecycle methods like componentDidMount. But with the hooks, we can put them into practise.
The hooks must be implemented inside a class component, though, which necessitates a different syntax. constructor(props){super(props);
this.state = {name:”}}
When it comes to hook implementation, the functional component can do it with ease. The example syntax is as follows: Const[name, setName] = useState(”)
Because they store the state, constructors are necessary.There is no use of constructor.


This article will help you to learn about class and functional components. Thank you for reading the article. Hope you understand very well about the components.


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