ReactJS Tutorial: A Step-by-Step Guide To Learn React
  • Intermediate
  • 12 Lessons
  • 3 hrs of Learning
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Tutorial Highlights

React is the most popular front-end JavaScript library in the field of web development. React is a JavaScript library created for building fast and interactive user interfaces for web and mobile applications. It is an open-source, component-based, front-end library responsible only for the application’s view layer. React gained popularity due to some of its salient features  - can be used for the development of both web and mobile apps, unidirectional data flow, reusable components, creation of dynamic applications, and many more. In our React tutorial, we cover all such features, explain what exactly React is and the benefits of using it, it’s components, state, and more. So start learning with our React tutorial, and broaden your knowledge and hone your skills now.

Skills Covered

  • Components
  • State
  • Props
  • Virtual DOM

Topics Covered

ReactJS Tutorial Applications 

ReactJS is a JavaScript library that provides a fast, lightweight, and modern way to execute code. Here are the most important applications of ReactJS you will learn in this ReactJS tutorial:

1. Creation of Dynamic Web Applications

Creating dynamic web applications requires a lot of complex coding. ReactJS makes this super easy by enabling HTML quotes and tags to render particular subcomponents.

2. Code Maintenance

One of the major advantages of ReactJS is the ability to reuse components. This makes it easier to manipulate and define the objects that are used, which in turn provides for better code maintenance.

3. Mobile App Development

ReactJS provides similar design patterns that facilitates the smooth transition of web applications to mobile application development. You can also build high-end UI apps for both Android and iOS systems.

ReactJS Tutorial: Table of Contents

The ReactJS tutorial covers following topics:

What is React? 

React is one of the most popular front-end JavaScript libraries in the field of web development. It is mainly maintained by Facebook and a large community of developers. A number of large, established companies (Netflix, Instagram, Airbnb, to name a few) use it to build their user interfaces and UI components. Whether you’re new to ReactJS or just want a quick refresh on its core concepts, this ReactJS tutorial will give you an introduction to React fundamentals, its features and components.

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Why use ReactJS?

The key objective of ReactJs is to develop User Interfaces that enhance the speed and performance of applications by using virtual DOM.  

Features of React.JS

  • JSX - It is an extension of ReactJS, which is not mandatory to be used but very beneficial if used since it is very easy to use.
  • Component: ​​Components are similar to pure javascript functions, and they serve to simplify the code by separating the functionality into reusable independent code. Components can be used as functions and as classes. Components also have a state, and props, which simplify lives. The status of each prop is preserved within a class.
  • Virtual DOM: React generates a virtual DOM, which is an in-memory data-structure cache. Only the final DOM updates have been updated in the browser's DOM.
  • Javascript Expressions: Curly brackets, for example, can be used to insert JS expressions into JSX files.

Advantages of ReactJS

  • ReactJS employs virtual dom, which makes use of an in-memory data-structure cache, and only the most recent modifications are updated in the browser's dom. This speeds up the app.
  • Using the react component feature, you may design components of your choice. The components are reusable and useful for code maintenance.
  • Since Reactjs is an open-source javascript library, it is simple to learn.
  • ReactJS has quickly gained popularity and is supported by Facebook and Instagram. Many well-known companies, including Apple and Netflix, use it.
  • Since Facebook maintains the library of ReactJS, it is well-managed and up-to-date.
  • ReactJS may be used to create sophisticated user interfaces for both desktop and mobile apps.

Disadvantages of ReactJS 

  • The majority of the code is written in JSX, which means that HTML and CSS are part of the javascript code. This can be perplexing because most other frameworks like to keep HTML separate from the javascript code.

  • ReactJS has a huge file size.


import React from 'react';

import ReactDOM from 'react-dom';


var name = "Learner";


var element = <h1>Hello, { name }.Welcome to our institution.< /h1>;






Output: Hello, Learner. Welcome to our institution.

React Props 

ReactJS follows a distinct approach to data flow and manipulation which can make it difficult to understand a number of concepts (props, state, etc.). This ReactJS tutorial will help you understand React Props, one of the most important concepts of ReactJS. The term "props" stands for "properties" and is used to pass data from one component to another. In this ReactJS tutorial, you will also learn about the React Props feature and understand the methodology to use it.

ReactJS State 

ReactJS State is another important concept of ReactJS. React State holds the data for a component. This component, in turn, returns the data contained within the state to the output. A component’s “state” can change over time. Whenever this happens, the component re-renders. In this ReactJS tutorial, you will learn about the basics of ReactJS State, the setState() method, and the differences between ReactJS Props and ReactJS. State.

ReactJS Components

ReactJS Components are the building blocks of any application created with ReactJS. It splits the user interface into independent parts, each of which can be processed separately. ReactJS Components allow you to reuse the user interface elements, which has made ReactJS so popular. In this ReactJS tutorial, you will learn about the different  types of ReactJS Components, nesting ReactJS Components and the lifecycle of React Components.

React with Redux 

Redux is a predictable state container for JavaScript apps. It helps to maintain the data flow and keep it organized as an application grows. In this ReactJS tutorial, you will gain a working understanding of Redux and its most basic concepts. There is also an added bonus in this ReactJS tutorial to help you create a simple ReactJS application with and without Redux to help you understand the difference in more detail. 

ReactJS Interview Questions

Since ReactJS is one of the most popular front-end technologies out there, more and more companies are looking for professionals with this skill. If you are preparing for a job interview, this ReactJS tutorial provides a comprehensive list of all the common ReactJS interview questions that are frequently asked in interviews. These interview questions are grouped into the following categories - basic interview questions, Component interview questions, Redux interview questions, Router interview questions and Styling interview questions.

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Using ReactJS from CDN

To use a CDN with React Js, include the CDN in your index.html file. You can accomplish this by inserting the following code into your index.html file: Replace "" with the CDN's URL.

Using NPM Packages- Npm packages are libraries of code that are provided by the community and can be installed into React projects with a few simple commands. Using npm packages helps developers save time by providing access to premade code instead of having to create code from scratch.

What is JSX?

JSX (JavaScript Extension) is a React extension that allows you to write HTML-like JavaScript code. In other words, JSX is a React-specific HTML-like syntax that extends ECMAScript to allow HTML-like syntax to coexist with JavaScript/React code.

Why Is Immutability Important?

Immutability is an important concept in computer programming, especially when developing applications that rely on data integrity and security. By making data immutable, developers are able to ensure that once a piece of information is entered, it cannot be changed or altered in any way. 

Working with External CSS in ReactJS

Working with style sheets is essential when it comes to ReactJS. External CSS in ReactJS allows developers to define specific styles to override the default styling. This means that developers can create unique designs and features to extend the functionality of the application. ReactJS allows developers to apply the styles directly to their components, making it easy to customize and maintain.

Function component

Function components are one of the primary building blocks of ReactJS. They let you define components that don’t need state or lifecycle methods. Function components can accept props as parameters and return React elements. This allows for easy reuse of code and a more consistent way of structuring applications.

Taking turns

Taking turns in ReactJS is a common pattern used to coordinate multiple components. By utilizing this pattern, components can communicate with each other in order to render content in a particular order. This can be particularly useful for creating complex interactive interfaces. Additionally, it can help ensure that a component renders properly when it is rendered out of order.

Declaring a winner

By allowing components to communicate with each other, ReactJS can determine which component should be rendered first and help decide the winner of the interaction. This helps developers build complex interfaces that have complex logic embedded into them and makes the process of declaring a winner much easier.

Adding time travel

Time travel in ReactJS can be implemented with the use of a game engine, allowing users to rewind and restart the game at any point. This feature can also be used to allow users to review previous moves and refine their strategy, so they can make better decisions in the future. 

Storing a History of Moves

This is done by using the browser’s history API to store the history of moves and enabling users to go back to the previous move. When a user clicks on the “Back” button, the game state can be changed to the previous move.


Lifting state, again

State lifting is often a difficult task for developers. It requires careful thought and precise implementation to ensure that the state can be properly lifted from the component and placed in a global store. This process can be simplified by using Redux, a library that allows for easy state management across components.

Showing past moves

This is done by your browser by using the past history search tab.

Picking a key

As this document progresses, one key point needs to be identified. This key point will be the focus of the document and will help dictate how the document is structured and the end result. With this in mind, the next step is to identify a key that will be the basis of the document. Once the key is identified, this key should be revisited throughout the document.

Implementing Time Travel

One of the latest features developers can use is time travel, which adds a unique element to projects. Through this feature, users can traverse through different states of their application as though they were traveling through time.

Working with forms

Working with forms in React JS is no exception. With React, you can easily create forms that are highly customizable and apply data validation to them. A variety of form components are also available for developers, such as input fields, dropdowns, radio buttons, and checkboxes. With React, developers can also create forms that are user-friendly and have a seamless flow from one form field to the next.

Working with Events in ReactJS

React JS offers developers a variety of ways to handle events within their applications. Events can be used to trigger action from a user, such as a click on a button. Developers can also use events to update their components and data, as well as provide feedback for users. React components can also register for events and listen for them, and then respond accordingly.

Working with Inline CSS in ReactJS

Working with inline CSS in ReactJS is a great way to style individual components and elements of an application. React’s inline styling syntax allows developers to specify styles on a per-component basis, which makes for a more efficient and organized workflow. Inline styles can be combined with global stylesheets, providing developers with the ability to add custom styling without needing to write large amounts of code.

Here’s What You Can Do Next

ReactJS is quickly becoming the developers’ go-to choice for building web applications, rising above its competitors Vue.js and Angular. Whether you’re a newbie or a developer looking to upskill, there’s a number of reasons why you should learn ReactJS. Simplilearn’s Post Graduate Program in Full Stack Web Development and Automation Testing Masters will help you master the fundamentals of React including JSX, props, state, and events. It also dives deep into Redux, covering topics like reducers, actions, and the state tree. Sign up for this course today and hop onto an exciting and promising career with ReactJS.

About the Author

Ravikiran A SRavikiran A S

Ravikiran A S works with Simplilearn as a Research Analyst. He an enthusiastic geek always in the hunt to learn the latest technologies. He is proficient with Java Programming Language, Big Data, and powerful Big Data Frameworks like Apache Hadoop and Apache Spark.

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