Category: Workshop

Using React JS in the HTML File

Learn how to use ReactJS directly in HTML files, including prerequisites and setup steps.

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

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

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

Follow the below steps to add react JS compnent to the HTML file.

Add the DOM container to mount ReactJS Component

Embedding React JS in HTML differs slightly from what we have done with React Js App. In a standard React Js app, the root element in the index.html is the container that mounts the React Js app. Similarly, we need any element to mount our react JS component in HTML file as below,

<div id="example"></div>

In above code, we have added an element with id example in HTML file.

Add required JS files to run ReactJS

We want to run a React app in an HTML file, where no node_modules to provide React Js dependencies. Therefore, we must add React dependencies by including React script tags in the HTML document as below,

<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>

In above code, we have included the required React JS scripts, which are required to execute the React JS code.

React Js code returns JSX. So, we also need Babel JS to transform that JSX as below,

<script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>

Write ReactJS code in HTML

Now, our HTML file is ready for react JS code. But, we have to add our react JS code in text/babel script tag as babel can transpile our react JS code as below,

<script type="text/babel">
  function Hello() {
    return <h1>Hello World!</h1>;
  }
  ReactDOM.render(<Hello />, document.getElementById('example'))
</script>

Example

The complete code of using React JS in the HTML file is as follows,

<!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

Get started with ReactJS, a powerful JavaScript library for building user interfaces. Learn key concepts, benefits, and how to create your first React app.

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

Resolve the “libpangox-1.0.so.0” shared library error in Anydesk on Ubuntu 22.04 LTS with this easy step-by-step fix and download instructions.

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

What is libpangox library?

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.

Install the library

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

sudo 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 this error 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

You need to manually download the .deb file using wget command. This package is available to many package libraries. I have downloaded it from Debian Package Library.

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

Install the downloaded .deb file using apt command as follows,

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

Step3: Restart the AnyDesk service

After successful installation, restart the anydesk service.

sudo service anydesk restart

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

Laravel Middleware Explained: What It Is & How to Create One

Learn what middleware is in Laravel, why it’s essential, and how to create custom middleware for handling requests efficiently. Step-by-step guide included.

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.

Create a custom middleware

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.

What are accessors and mutators?

Understand accessors and mutators with real-world examples. Learn how to format and modify model data automatically.

Accessors and mutators are public member functions in a class that exists solely to set or get the value of a class member variable. They are often referred to as getter and setter or set and get functions. I will use the term setter for mutators and getter for accessors for this article.

Many programmers think why we should create getter and setter functions when we can declare public member variables and access them easily using the object of the class. But, there are many benefits from a software engineering point of view to create classes with only private member variables and use getters and setters to manipulate their values.

One of the primary benefits of object oriented design is combining the data and the methods that operate on them into a single component. This is referred to as encapsulation. It allows you to hide the actual implementation of the class from the users of the object. It allows the programmer to make changes in the hidden part of the class design without affecting the users of the objects derived from the class. So if you created some complex class and sold it to a bunch of other developers, you could make changes to your class to improve performance of the hidden part, and they would not have to rewrite their code to use newer versions.

Another crucial benefit of setter functions is that, you can validate the data before set the value. For example, we have created one class for accounting and let’s assume the maximum value for any transaction is 10000. With a public variable, there is no way to stop someone from setting this value to 20000.

Naming conventions

Typically, programmers name getter functions as “get” followed by the name of the variable being accessed and setter functions as “set” followed by the variable name.

Getters and setters in use

The example below adds getters and setters to our Accounting class. 

class Accounting
{
private:
  int transactionLimit;

public:
  // setters
  bool setTransactionLimit(int);

  // getters
  int getTransactionLimit();
};

// Setter function perform input validation
bool Accounting::setTransactionLimit(int l) {
  if (l < 0 || l > 10000)
    return false;
  else {
    transactionLimit = l;
    return true;
  }
}

// Simple getter functions. This hide the 
// actual method of storage from object user.  
int Accounting::getTransactionLimit() {
  return transactionLimit;
}

In above class, the setter functions also validate the input and return true if the value is acceptable or false if not. In that way, the programmer using the class can know if the provided value is valid and write the code to respond in an appropriate manner.