Getting started with ReactJS

Setting up a local environment is recommended way to learn ReactJS because the local setup allows you to complete the tutorial using your choice of editor, use the latest JavaScript features, provides a nice developer experience, and optimizes your app for production.

Let’s start with creating a new ReactJS application.

Create React App

Creating React App is a comfortable environment for learning and building an application in React.

There are few prerequisites for creating a React app as follows,

  • Node.js >= 14.0.0
  • npm >= 5.6

If above requirements are satisfied, you can run the following command to create a new react application,

npx create-react-app my-react-app

You can change my-react-app to anything you want to name your app.

The create-react-app command will set up everything you need to run a React application. Now you are ready to run your first real React application! Go to your application directory using the following command,

cd my-react-app

Now, run the following command inside your application directory to run your application,

npm start

It will compile your application and open it in the new browser window or tab. If not, you can open your browser and write localhost:3000 in the address bar. Your application will look like screenshot below,

If you check your command window, it will show the following output,

You can see that command window is also providing command to create a production build for your application.

Using ReactJS in the HTML File

Now that we know what ReactJS is, we can start with different usage of ReactJS. If you don’t know what ReactJS is, read the ReactJS introduction.

In this article, we will learn to use ReactJS directly in the HTML file. There are some prerequisites to adding ReactJS script inside the HTML code. We need to include the following three javascript in the head section of the HTML file.

  • ReactJS
  • ReactDom
  • Babel

The first two allow us to write ReactJS code in our JavaScripts, and Babel will allow to write JSX syntax and ES6 in older browsers.

Example

Let’s see an example of using ReactJS in the HTML file,

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <script src="https://unpkg.com/react@18/umd/react.development.js" crossorigin></script>
    <script src="https://unpkg.com/react-dom@18/umd/react-dom.development.js" crossorigin></script>
    <script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>
  </head>
  <body>
    <div id="example"></div>
    <script type="text/babel">
      function Hello() {
        return <h1>Hello World!</h1>;
      }
      ReactDOM.render(<Hello />, document.getElementById('example'))
    </script>
  </body>
</html>

This way, we can use ReactJS for testing purposes. But for production use, we have to set up a React environment.

ReactJS Introduction

ReactJS is one of the most popular JavaScript front-end libraries for building user interfaces with a strong foundation. It has a robust and rapidly growing developer community and a declarative, efficient, and flexible library for building reusable UI components. It is an open-source, component-based front-end library responsible only for the application view layer. 

ReactJS is one of the most popular JavaScript front-end libraries for building user interfaces with a strong foundation. It has a robust and rapidly growing developer community and a declarative, efficient, and flexible library for building reusable UI components. It is an open-source, component-based front-end library responsible only for the application view layer. 

Initially, it was developed by Jordan Walke, a software engineer at Facebook and maintained by Facebook. Later, it was used in other Facebook products like WhatsApp & Instagram. Facebook implemented ReactJS in its newsfeed section in 2011, but it was released to the public in May 2013.

The main objective of ReactJS is to develop interactive User Interfaces (UI) with the help of virtual DOM (JavaScript object) to improve application performance because the JavaScript virtual DOM is faster than the regular DOM because, it only changes individual DOM elements instead of reloading complete DOM every time. It uses component and data patterns that improve readability and helps to maintain larger apps.

The components are the heart of all React applications. These component are used to make a React application. Each component is responsible for outputting a small, reusable piece of HTML code and can be nested with other components to allow complicated applications.

Solved – error while loading shared libraries: libpangox-1.0.so.0: Anydesk on Ubuntu 22.04 LTS

After successfully upgrading from Ubuntu 20.04 LTS to 22.04 LTS, most of the applications are working perfectly. But, some of the applications behave unusually. Such as, I tried to run the Anydesk application, but it doesn’t launch/start. when I checked the status service, the AnyDesk service was failed and the reason for failing is mentioned in the below error message,

anydesk: error while loading shared libraries: libpangox-1.0.so.0: cannot open shared object file: No such file or directory

libpangox-1.0.so.0 is a library used for text layout and rendering the text. Most of the work on Pango-1.0 was done using the GTK+ widget toolkit as a test platform.

So, I ran the command to install it using the apt as follows,

apt install libpangox-1.0-0

But, it gives me the following error,

Package libpangox-1.0-0 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

So, from that we can understand that, libpangox-1.0.so.0 can’t be installed from apt or apt-get. We need to install it manually.

Use the following steps to install libpangox-1.0.so.0 manually,

Step 1. Download the libpangox-1.0 package

wget http://ftp.us.debian.org/debian/pool/main/p/pangox-compat/libpangox-1.0-0_0.0.2-5.1_amd64.deb

Step2: Install the package using apt

sudo apt install ./libpangox-1.0-0_0.0.2-5.1_amd64.deb

Step3: Restart the AnyDesk service

sudo service anydesk restart

After these steps, if you check the AnyDesk service status, it will show active (running).

What is Middleware and how to create one in Laravel?

It’s best to envision middleware as a series of “layers” for HTTP requests that must pass through before they hit your application. Each layer can examine the request and even reject it entirely.

Middleware provides a convenient mechanism for inspecting and filtering HTTP requests entering your application. It’s best to envision middleware as a series of “layers” for HTTP requests that must pass through before they hit your application. Each layer can examine the request and even reject it entirely.

For example, Laravel includes a middleware that verifies the authenticity of the user of your application. If the user is not authenticated, the middleware will redirect the user to your application’s login screen. However, if the user is authenticated, the middleware will allow the request to proceed further into the application.

To perform different tasks, we can develop many middlewares besides authentication. For example, a logging middleware might log all incoming requests to your application. 

Laravel framework has included many middlewares, including middleware for authentication and CSRF protection. All of these middlewares are located in the app/Http/Middleware directory.

To create a middleware, we can use the following command,

php artisan make:middleware <middleware-name>

For example, if we want to create a middleware for checking transactions, we can run the following command,

php artisan make:middleware CheckTransaction

 After successful execution of the command, a middleware class will be created under the app/Http/Middleware directory.

In this class, we can define methods to check transactions. If the transaction is not completed, we can redirect the user back to the failed transaction page. However, on the successful transactions, we can allow users to proceed to the next page.

<?php
 
namespace App\Http\Middleware;
 
use Closure;
 
class CheckTransaction
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        if ($request->input('status') !== 'completed') {
            return redirect('transaction-failed');
        }
 
        return $next($request);
    }
}

As you can see, if the transaction status does not set to “completed”, the middleware will return an HTTP redirect to the client; otherwise, the request will be passed further into the application.

To pass the request deeper into the application (allowing the middleware to “pass”), you should call the $next callback with the $request.