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In this introduction, you will understand what React JS is and learn how to use NPM commands to get started with React, such as install and start.

React is a popular tool for building UIs (user interfaces) on the web. If you are new to web development, you may wonder what React is and how it can help you create better user experiences.

So, in the following section, you will understand what react is. Let’s get started.

A JavaScript Library React JS (also known as React) which is mostly used in front-end web development.

It makes designing interactive user interfaces more simple whereas page rendering with dynamic and data makes HTML elements quite easy. React, developed and maintained by the Facebook team lets you develop large web applications that can change data without reloading

At the core of React is its ability to divide complex user interfaces into small, reusable parts. That allows for more efficient and maintainable development.

React.js follows the declarative programming model, where developers describe what should happen with a user interface. And a conditional from React that deals with the rendering logic.

The main reason for this is a vDOM with React to keep track of the changes in your app’s state. So it can update only what needs updating and avoid expensive manipulation directly on the browser resulting in more performance.

Lots of people use and support React. It’s free and open for anyone to use. That means a lot of smart developers around the world help make it better.

Let’s take a brief look at the history.

Jordan Walke, a software engineer at Facebook is the person who developed React JS first in 2011. It was developed due to the increasing complexity of Facebook’s dynamic user interfaces and traditional JavaScript frameworks couldn’t handle these frequent modifications, with framework inefficiency at processing data.

Initially, React.js originated at Facebook and was first used internally in its newsfeed before the realization of what it could be. The React library was open-sourced by 2013 when Facebook released it as a JSConf US conference. This made the wider developer community able to partake in developing new functions for this library it has gained popularity quickly due to its different way of thinking about UI development.

Over the years, React has evolved a lot and it receives many updates with various improvements. Such as new features like hooks — that allow functional components to manage state and side effects. Or even an internal rewrite of its core algorithm called Fiber which aims for more performant rendering.

Today it is one of the few and most popular libraries in Front-end development! It has been since used by individuals from all around the world to create some marvelous websites, not only that even leading Organizations like Facebook, Instagram Airbnb Netflix started using React which makes it a must-have tool for any web-developer right now.

In the following section, you will understand how the virtual dom works in React.js.

The virtual dom is one of the most ingenious ideas that have made React super fast and powerful for developing dynamic user interfaces. That is one of the basic concepts React uses to optimize app performance—allowing developers to build very responsive applications, without worrying about it being slow or inefficient.

The Virtual DOM (VDOM) is simply an in-memory representation of actual DOM elements. It is a lightweight copy of the actual DOM, providing React the ability to do fast updates with minimal direct manipulation which can be slow and computationally expensive.

Here’s how the Virtual DOM works in the React.js application:

React will build a Virtual DOM tree when the component is first rendered. This is a representation in memory of the VDOM structure which has a form similar to real DOM. This VDOM is used by React.js to manage and track the changes in UI.

As soon as some state or props get changed for a component then react re-render the components which generates a new Virtual DOM tree. React does not update the real DOM right away; instead, it compares the new Virtual DOM tree with the previous one and finds out what has changed. This operation is also known as “diffing”.

This is when two lists of elements are compared and the minimum number of operations required to adjust a list can be applied as mutations on an actual DOM. Virtual DOM will compare the elements in both Virtual DOM trees and identify which exact element has been changed, removed, or added.

This is where react compares the virtual and real DOM to learn what has changed, so it can propagate the necessary updates without you telling it how or re-rendering everything all out. This process is called Reconciliation which makes UI to be updated efficiently and quickly.

It batch updates together for optimized rendering performance. Instead of touching the real DOM for every single change that is made, React holds changes and updates a virtual DOM layer inside until at some points determined to make all updates in one-time batch mode reducing touching the visual DOM.

Another key concept in React is the use of JSX (JavaScript XML), which allows you to write HTML-like syntax directly in your JavaScript code. JSX is not required to use React, but it makes it easier to create and manage complex UIs.

Anyway, in the following section, you will learn how to write an application using React.js.

To begin, it is necessary to install a recent version of node.js on your computer. To install it, follow the instructions on the&nbsp;<a href="https://nodejs.org/en/download/current" target="_blank" rel="noreferrer noopener nofollow">official page</a>.

Once installed, you can verify NPM and Node.js by using the command below.

If everything is ok, you can start your first app with React.js. Simply run the command below and follow its instructions.

After executing this command, you will need to wait for a moment while the folder is being downloaded.

If you take a look at this image, you will be able to see the packages that will be installed in the node modules folder, such as:

And there are some commands that you can use to run your React app.

When you open the project folder, you’ll find two files called “package-lock” and “package.json.” You’ll also see three folders, which are named as follows:

These files are all about Webpack, a tool that helps you mix together JavaScript, CSS, and other files and put them into the public folder.

Right now, you don’t need to worry about what’s inside these files. We’ll go over what they do in our next lesson. Let’s concentrate on making your first React app instead.

Anyway, before getting started, you have to learn more about Node NPM.

Let’s start the React application with the following command:

Once you run this React app through the previous NPM command, it will open the browser with this URL&nbsp;<code>http://localhost:3000/</code>.

As in the above introduction, React.js is a popular Javascript library for building dynamic user interfaces, particularly slick single-page web applications.

How does React.js help in building user interfaces?

In React reusable components are used when building multiple complex user interfaces ensuring a consistent and easy-to-use experience for the developer.

What is the main benefit of using React’s Virtual DOM?

The Virtual DOM increases performance by updating just what is needed to the actual DOM, rendering as fast as it can.

Facebook developed React.js, and it was released in 2013.

What were the reasons behind the development of React.js?

As I mentioned in the above introduction, React.js was created to solve this problem and make our lives easier when building highly scalable web applications.

How has React evolved since its initial release?

Since its release, It has introduced hooks, context API, and performance optimizations, making it more powerful and easier to use.

It supports a component-based architecture, Virtual DOM and JSX with unidirectional data flow.

When you create the component, you define its behavior by writing code that describes how it should render based on its current state and any incoming data or props. The component’s state is managed by React, and any changes to it trigger a re-rendering of the component and its child components.

One of the key features of React is its virtual DOM (Document Object Model). The virtual DOM is a lightweight representation of the actual DOM, and it allows React to efficiently update the UI without directly manipulating the DOM. When you update the state of a React component, React will compare the new virtual DOM with the previous one and only update the parts of the actual DOM that have changed. This makes React faster and more efficient than other approaches to UI development.

React also provides a unidirectional data flow, meaning that data can only flow in one direction, from parent components down to child components. This makes it easier to manage and debug your application, as you always know where the data is coming from and where it is going.

To get more details about how Virtual DOM works, scroll up into the React.js introduction and read the steps related it in detail.

What is the purpose of the diffing algorithm in React?

Using a diffing algorithm, the Virtual DOM can discover what has changed between renderings and because of this optimization updates are rendered more effectively.

What is the reconciliation process in React.js?

Reconciliation is the process in which React updates RealDOM to be the same as Virtual DOM after change detection.

What is JSX and why is it useful in React development?

JSX is a syntax extension of JavaScript, it makes writing HTML code within the JavaScript file which can be used to create react components.

What steps are involved in creating your first React app?

It includes steps like installing Node.js and starting up the development server of a React application in Node.js using<code class="inline-code">&nbsp;<code>npx create-react-app</code></code><code></code>.

What are the necessary tools to install before starting with React?

Install Node.js, NPM (Node Package Manager), and a code editor like VS Code.

How do you verify the installation of Node.js and NPM?

Check by running node -v and npm -v in the terminal to see which versions installed

What are the contents of a React project’s initial structure?

If we look at the structure, it consists of the <code class="inline-code">node_modules</code> folder (our system), src, public folders, and setup files like package.json.

What is the significance of the node_modules, src, and public folders in a React project?

The dependencies are located inside of the&nbsp;<code><code class="inline-code">node_modules</code></code>&nbsp;folder, the source code is found within src, and any static files will be placed in public.

How do you start a React application using NPM?

Start a React app by running the command&nbsp;<code><code class="inline-code">npm start</code></code>&nbsp;in the terminal.

What happens when you run a React app using npm run start?

The app will compile, run a development server, and open the browser showing your application immediately updating every time you save.

This Introduction brings forward a well-organized outline of the concepts covering the core functions of the React JS framework. React is really one of the most famous libraries for web user interface design. It is frequently utilized for building effective UIs, with a focus on SPAs. The very first aspect mentioned is the introduction to React. It gives an idea of how the user interface with many interacting parts can be realized in a simpler manner. This is made possible by the use of components. Also, the article brings up the benefits of using React. For example, the Virtual DOM is responsible for re-rendering only the portions of the application that have changed. This functionality enhances the speed of use of applications.

Next in turn the article speaks about installing Node on your home machine. It deals with configuring most of the rest of the environment. Calling <code class="inline-code">npm start</code>, the React setup creates a new application. The article however gives a little description of some crucial documents and directories. It describes <code class="inline-code">node_modules</code>, src, public files, etc. Last but not least, it describes how Webpack helps to keep project files organized.

Montasser Mossallem

In this introduction, you will learn what React.js is (JavaScript library) and how to build your first app using its key features. Click here.

React JS Introduction: What is React? the JavaScript Library

React.js Introduction

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React.js Tutorial

Through this article, you will learn how to install React on common operating systems such as Windows, macOS, and Ubuntu. Just pay attention.

Initially, it’s important to note that the React library is an open-source project designed by Jordan Walke, who was working at Facebook as a software engineer.

Anyway, in the next section, I am going to show you how to install React on several operating systems. Let’s dive right in.

To install React on any operating system, you have to install Node.js and the NPM package manager.

Installing React on Windows, macOS, and Ubuntu

To download Node.js, you must navigate to the&nbsp;<a href="https://nodejs.org/en/download/current" target="_blank" rel="noreferrer noopener nofollow">official page</a>. However, ensure that the version number of the Node.js installer is up to v14.0.0.

If you already have Node.js installed on your machine and the version is lower than 14.0.0, you can upgrade to 14.0.0 by using&nbsp;<a href="https://flatcoding.com/tutorials/learn-nodejs/install-nodejs-nvm/" target="_blank" rel="">NVM</a>, which stands for Node Version Manager.

So, to install NodeJS using NVM you just have to run the following command on the Command Prompt.

Note: the reason for ordering the installation of this version, because you will use the npx command, and this is not included in node versions before 14.0.0.

Here you have to make sure from which version of node.js you are using. And to do that, execute the following command.

Here is a command that helps you obtain information about the current NPM version on your operating system.

If the node.js version is prior of 14.0.0 , you can use the NVM command to switch between NodeJS versions. And to do that, run the following command.

In the next paragraph, I am going to cover the React installation on macOS.

To install React on macOS, you have to navigate to the&nbsp;<a href="https://nodejs.org/en/download/" target="_blank" rel="noreferrer noopener">official page</a>&nbsp;and download the installer for macOS. Additinally, you can install React on the Ubuntu operating system by the following instructions.

Here is the command which helps you to install NPM on your OS.

In the next section, you will learn how to create React application.

To create React application, you have to run the following command.

Once it finishes the download, you will see instructions in the command line interface to start the web pack server.

Let’s explore the React folders and files to see the tasks of each one.

The following image shows you the structures of the React app.

The React app is containing the following list

In this tutorial, you have learned how to install React on common operating systems such as macOS, Windows, and Ubuntu.

Additionally, you learned how to create a React application and explored the application’s files and folders.

To install React.js on macOS, and Windows, you have to download the Node.js installer and for Ubuntu, use: sudo apt-get install nodejs...

How to Install React on Ubuntu, Windows and MacOS

Install React

Rendering HTML in React might sound like a complicated task, but it’s actually quite simple once you understand the basics. In this tutorial, you will learn how to render HTML in React using several methods.

So, let’s get started with an overview of what is happening behind the scenes before rendering HTML.

When rendering HTML in a React application, several processes occur behind the scenes. These steps transform the React components into actual HTML elements that users can see in their browsers.

When you define React components, they can be either class-based or function components. Each component returns a description of what the UI should look like.

It is time for JSX compilation, as the browser cannot understand JSX code, so Babel compiles it into JavaScript. Here is an example of compilation:&nbsp;<code><code class="inline-code">&lt;span&gt;Hello CodedTag!&lt;/span&gt;</code></code>&nbsp;is compiled to&nbsp;<code><code class="inline-code">React.createElement('span', null, 'Hello CodedTag!');</code></code>.

React keeps a simple version of the real DOM called the virtual DOM. When a component shows up on the screen, React makes a virtual DOM tree from the component’s JSX. This virtual DOM is a JavaScript object that looks like the actual DOM’s structure.

When props or state change, React update the Virtual DOM. That can happen, according to a diffing algorithm to determine what has changed between the previous and current virtual DOM states.

After determining the changes, React updates the real DOM. It does this efficiently by only changing the parts of the DOM that have actually been altered. This minimizes the number of manipulations and improves performance.

Finally, the real DOM updates are rendered to the screen. The browser takes care of displaying the updated DOM elements to the user.

Anyway, let’s see how to render the HTML using the render method in the following section.

Acctually, the&nbsp;<code><code class="inline-code">render</code></code>&nbsp;method is a part of React’s Component class. It returns a single React element, which is then rendered to the DOM. Here’s a basic example:

React also supports functional components, which are simpler and do not use classes. Here’s the equivalent example using a functional component:

So, the component method should have a return expression to return the HTML DOM elements. Then, pass the main component name into the render function to merge the new elements into the real DOM.

Additionally, you can render HTML tags using another method. Let’s move to the following section to see how to use it.

Rendering HTML Using dangerouslySetInnerHTML Attribute

The&nbsp;<code><code class="inline-code">dangerouslySetInnerHTML</code></code>&nbsp;attribute allows you to render raw HTML within your components. The general purpose of this attribute is that you can save raw HTML in a database, and then, when you retrieve it, it can be rendered using the&nbsp;<code class="inline-code">dangerouslySetInnerHTML</code>&nbsp;attribute.

But Using&nbsp;<code><code class="inline-code">dangerouslySetInnerHTML</code></code>&nbsp;can expose your application to XSS attacks. And that can happen if the HTML content is not properly sanitized. So make sure you sanitize your inputs and it should be from trusted sources.

In this tutorial, you learned how to render HTML using the&nbsp;<code><code class="inline-code">render</code></code>&nbsp;function in&nbsp;<a href="https://flatcoding.com/tutorials/learn-react/" rel="" target="_blank">React.js</a>. Here are some processes that happen behind the scenes before rendering it:

Also, you understood how to display HTML using the&nbsp;<code>dangerouslySetInnerHTML</code>&nbsp;attribute, but using this attribute requires some attention, such as sanitizing the HTML elements to prevent your application from XSS attacks.

For more details, visit the&nbsp;<a href="https://react.dev/" target="_blank" rel="noreferrer noopener nofollow">official page</a>&nbsp;of React.js. Thank you for reading. Happy Coding!

Learn how to render HTML in React using the render() function, and use the dangerouslySetInnerHTML attribute for embedding raw HTML content.

How to Render HTML Elements in React.js

Render HTML

[h2] List of Tutorials
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Below is a list of React. These tutorials to get started and learn this library. It will cover different parts of React on each tutorial — ranging from introductory concepts for beginners to more advanced topics for experienced developers.
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[chapters-posts]

In this tutorial, We're going to cover complete React basics. Complete tutorial for developing user interfaces using this powerful JavaScript library.
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React. jsJS is an open-source, Component-Based JS Framework for Building Real-Time UIsCase framework designed to create dynamic and interactive user interfaces on single page application. React is an open-source, front end JavaScript library for building user interfaces or UI components that manage their own state and it's more easily to deploy part of a web page compare other component libraries. React. js is dedicated to efficiently rendering views that update only the components of a UI which are changing and enabling easy creation of web user interfaces.

Learn React.js using a simple and intuitive guide provided by our creative web development team on the most basic to progressive front-end developments.

List of Tutorials

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