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React vs Angular: An In-depth Comparison

There is lot of buzz in the market about Angular and React. You might have come across these two front-end technology stacks, irrespective of whether you are an experienced professional or a beginner in the field of programming. A question that may plague most of you is---which of these two is the better technology to master, in terms of a career and which one is easier? Being a full stack developer, I will try to explain in-depth the difference between the two, based on my personal experience.So, let’s start right at the beginning and understand what React and Angular are: -React – In simple terms React is a JavaScript library for building interactive user interfaces. It is maintained by Facebook and a community of individual developers and companies.Angular – Angular is a JavaScript framework for web application development, led by the Angular Team at Google and by a community of individuals and corporations.Let’s first understand these two terms: JavaScript Library and JavaScript framework.   Consider a scenario of writing a hide and show functionality on a web page for a simple div and the amount of code we have to write for the same. Using a JavaScript library as jQuery we can use inbuilt functions like hide() and show() and complete the number of lines of work by simply using a function.To learn more about jQuery, please go through the official site at this link: https://jquery.com/ .So, in other words, a library has a set of defined functions which will help us to design interactive front-end applications easily, whereas JavaScript framework is a collection of such libraries which has tons of inbuilt functions which speed up our website development.  React being a JavaScript library has inbuilt functions, but Angular being a Framework has a collection of inbuilt functions. So, when it comes to inbuilt functions, Angular gives us a wide range of options. Now let’s try and understand the difference between React and Angular:Technical ConsiderationsAngularReactJavaScriptFrameworkLibraryDocument Object ModelReal DOM – DOM organizes the HTML documents in the form of a tree. In Angular, Real DOM is used which means the whole tree structure is refreshed when a single change is made. This makes the process slower.Virtual DOM – With this you can change any element very quickly and without needing to render the whole DOM. It drastically changes the performance from good to excellent.Programming LanguageTypeScriptJavaScriptTemplateTypescript inside HTMLHTML inside JavaScriptData BindingTwo-way- In which model state changes automatically when any change in UI element is made, and vice-versa.One-way- In which the UI elements can be changed only after changing the model state. The developers cannot alter the UI elements without updating the corresponding model state.PerformanceBecause of real DOM it is slow compared to ReactAs React uses virtual DOM, it is faster than AngularTypes of AppsUsing Angular we can build large complex Enterprise applications, Single Page applications, as well as Mobile ApplicationsSmall Applications, Native mobile applicationsThese are the key differences between these two technology stacks. If you wish to dig deeper, you can find more differences over the internet. So are you planning to master either of these two? You can, but there are certain prerequisites you should know before you get started.Angular – As Angular is a JavaScript framework basically written in TypeScript, one should be well versed with JavaScript basics as well as advance concepts. Without knowing TypeScript, it is difficult to master Angular.Generally, for Angular based applications Testing and Debugging are possible with a single Tool. Whereas for React applications, we have to use various sets of tools for Debugging and Testing.React – React, on the other hand, is a much easier library to master than Angular. Anyone who knows the basics of JavaScript syntax and HTML syntax can learn React.JSX – Is an XML-like language that allows you to write mark-up directly in your JavaScript code. React decided to combine them within components using JSX. JSX syntax is like writing HTML inside JavaScript, so if you know the basics of JavaScript and HTML it becomes easier for you.Being a developer, I always love to understand concepts using sample code snippets. Here are some code snippets, to help you understand these technology stacks better.React Sample Code for Hello World:It’s basically a standard JavaScript class which returns HTML. With React components we import React at the top using a standard JavaScript import statement and then declare a component using a standard JavaScript class.   The syntax you see above inside the render () function is JSX which simply compiles to JS. This is the most basic React code for a developer to start with, as it is a simple JavaScript function and is easy to understand.Angular Sample Code for Hello World:Above is a simple Angular component file which is written in TypeScript where @Component defines the metadata of component. The selector is the custom HTML name we’ll use to include this component. We’ll add a message variable inside of the demo component class and define its type as a string. Inside the ngOnInit method, we’ll give it a default value. ngOnInit is a life cycle method that executes before the component is mounted. We can also use the constructor for this purpose, as they will both give the same result for this application.Next, we have created the HTML, where we are using an H1 tag to display the current value of the message variable. The double braces are used to interpolate the value of the message. We’ll also create a form without an action, which consists of a label and an input field of type text. To create a two-way binding, we need to use ngModel which will allow us to change the value of the message variable and then the name property will display the value of the variable inside of the input field. So, before we type anything, it should have the default value “Hello” written into it.  Once we include this component inside our main component and run the application, we will see the output as Hello. This is an example of Two-way Data Binding, since changing the input immediately reflects on the browser.I have written these two-sample codes to explain the approach of React and Angular. Notice how the different coding styles can help differentiate between the code written in Angular and React. For a beginner or experienced programmer, it is important to get the hang of the coding style of a particular language to develop expertise in it.Till now we have seen the technical differences of Angular and React. But to understand which technology stack to pursue it is important to gauge your interest in the particular framework or language and its popularity in the real world.  In other words, understand which companies are using that technology. Let’s now look at who around the world is using React and Angular.FACEBOOK – The tech giant Facebook is the founder of React and majorly uses React components in Facebook, which is one of the highest traffic sites. Similarly, it is used in WhatsApp and Instagram which has an even larger user base. GOOGLE – Google is the founder of Angular. It uses Angular in several of its internal projects, as well as in many customer projects because of its MVC Architecture. Sitecore - is a customer experience management company that provides web content management and multichannel marketing automation software. It has a complete Sitecore JavaScript Services SDK for JavaScript developers that enables building full -fledged solutions using modern JavaScript UI libraries like React and Frameworks like Angular. This helps us gauge the popularity of React and Angular. Facebook and Google are just two of the most popular companies using these technologies. There are several enterprises around the world that have adopted and benefited from React and Angular. So, now that you know that both are equally popular, let us try and understand which one of the two is easier to learn.Since to learn anything it is important to have a solid foundation, the easier technology to learn would be the one where the prerequisites to learn it are easier. Another important factor is Community Support which is very important when it comes to learning a new technology. A growing and active community plays a major role is helping one master a technology stack.Learning CurveReact – Personally I feel learning React is easy as it is based on JavaScript. If we are well versed in advanced JavaScript concepts, we can do very well in React. If you want to explore the ways to get started with React, please go through these listed resources which are very useful for a beginner: Angular – The learning curve for Angular is steeper than React, as Angular is a complex and verbose framework. TypeScript may look similar to JavaScript but takes a little longer to learn.  Beginners should always start with what is easier, and then gradually move towards complex code, so it makes sense to start learning React first and then get into Angular.I am going to list a few blogs as references, which I think are wonderful resources in the journey of exploring and learning Angular and its concepts. Community Support & UpdatesAngular releases newer versions or updates every six months. So, in a year, there are two major releases or updates to make necessary changes. Developers have experienced many changes since its release and the current version is version 10.  Angular is supported by huge and active communities of Google.React is maintained by Facebook and its current version is 16.13.1. Upgrades in React are easier than in Angular. Also, stability is a major concern when it comes to releasing newer versions of React, since big companies like Twitter and Airbnb use it. It also has good community support.MigrationUpdates and Migration are also important aspects of any project created in React or Angular. React projects are easy to migrate and update as Facebook developers give regular updates along with breaking changes updates.With migration projects, we can migrate one part of a page component wise. This ensures that there are no breaks in the other functionalities of a working project. Because of this feature, Facebook has been successful in migrating many of its pages into React components.Whereas, Angular is not that easy to migrate, as a lot of its libraries have to be used in a single project and because of its two-way binding it is connected to modal state as well. Angular projects are large and complex, and it takes proper planning and timelines to migrate full projects.When you are migrating your project, there may be a need to add some React code to the site. To learn more about how you would do this, read. Let’s see the latest Google Trends to compare the popularity of Angular and React along with stack overflow Trends. Google Trends: Image SourceStack Overflow:Image SourceThe above graph gives you an idea of the presence and popularity of React and Angular in the present market. React leads the race because of its simple and easy syntax that makes it more appealing to beginners and companies who are adopting it for small projects. But Angular also has its own unique features which are being used by lots of developers for enterprise level applications. Conclusion  Through this post I have tried to explain some important aspects of React and Angular and the differences between the two. I would recommend that those who wish to master these two technologies, go through the official documentation of Angular and React as it explains a lot of concepts and components in a detailed manner. Going through the official documentation is always a great option to learn any new technology and follow along. At the end I am listing out the links of official sites for learning resources of Angular and React. I am also going to list out a few references of important concepts of React and Angular which are very important for a beginner to start with. 

React vs Angular: An In-depth Comparison

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React vs Angular: An In-depth Comparison

There is lot of buzz in the market about Angular and React. You might have come across these two front-end technology stacks, irrespective of whether you are an experienced professional or a beginner in the field of programming. A question that may plague most of you is---which of these two is the better technology to master, in terms of a career and which one is easier? Being a full stack developer, I will try to explain in-depth the difference between the two, based on my personal experience.

So, let’s start right at the beginning and understand what React and Angular are: -

  • React – In simple terms React is a JavaScript library for building interactive user interfaces. It is maintained by Facebook and a community of individual developers and companies.
  • Angular – Angular is a JavaScript framework for web application development, led by the Angular Team at Google and by a community of individuals and corporations.

Let’s first understand these two terms: JavaScript Library and JavaScript framework.   Consider a scenario of writing a hide and show functionality on a web page for a simple div and the amount of code we have to write for the same. Using a JavaScript library as jQuery we can use inbuilt functions like hide() and show() and complete the number of lines of work by simply using a function.

To learn more about jQuery, please go through the official site at this link: https://jquery.com/ .

So, in other words, a library has a set of defined functions which will help us to design interactive front-end applications easily, whereas JavaScript framework is a collection of such libraries which has tons of inbuilt functions which speed up our website development.  

React being a JavaScript library has inbuilt functions, but Angular being a Framework has a collection of inbuilt functions. So, when it comes to inbuilt functions, Angular gives us a wide range of options. 

Now let’s try and understand the difference between React and Angular:
React vs Angular: An In-depth Comparison

Technical ConsiderationsAngularReact
JavaScriptFrameworkLibrary
Document Object ModelReal DOM – DOM organizes the HTML documents in the form of a tree. In Angular, Real DOM is used which means the whole tree structure is refreshed when a single change is made. This makes the process slower.Virtual DOM – With this you can change any element very quickly and without needing to render the whole DOM. It drastically changes the performance from good to excellent.
Programming LanguageTypeScriptJavaScript
TemplateTypescript inside HTMLHTML inside JavaScript
Data BindingTwo-way- In which model state changes automatically when any change in UI element is made, and vice-versa.One-way- In which the UI elements can be changed only after changing the model state. The developers cannot alter the UI elements without updating the corresponding model state.
PerformanceBecause of real DOM it is slow compared to ReactAs React uses virtual DOM, it is faster than Angular
Types of AppsUsing Angular we can build large complex Enterprise applications, Single Page applications, as well as Mobile ApplicationsSmall Applications, Native mobile applications

These are the key differences between these two technology stacks. If you wish to dig deeper, you can find more differences over the internet. 

So are you planning to master either of these two? You can, but there are certain prerequisites you should know before you get started.

  • Angular – As Angular is a JavaScript framework basically written in TypeScript, one should be well versed with JavaScript basics as well as advance concepts. Without knowing TypeScript, it is difficult to master Angular.

Generally, for Angular based applications Testing and Debugging are possible with a single Tool. Whereas for React applications, we have to use various sets of tools for Debugging and Testing.

  • React – React, on the other hand, is a much easier library to master than Angular. Anyone who knows the basics of JavaScript syntax and HTML syntax can learn React.
  • JSX – Is an XML-like language that allows you to write mark-up directly in your JavaScript code. React decided to combine them within components using JSX. JSX syntax is like writing HTML inside JavaScript, so if you know the basics of JavaScript and HTML it becomes easier for you.

Being a developer, I always love to understand concepts using sample code snippets. Here are some code snippets, to help you understand these technology stacks better.

React Sample Code for Hello World:

React vs Angular: An In-depth Comparison

It’s basically a standard JavaScript class which returns HTML. With React components we import React at the top using a standard JavaScript import statement and then declare a component using a standard JavaScript class.   

The syntax you see above inside the render () function is JSX which simply compiles to JS. This is the most basic React code for a developer to start withas it isimple JavaScript function and is easy to understand.

Angular Sample Code for Hello World:

React vs Angular: An In-depth Comparison

Above is a simple Angular component file which is written in TypeScript where @Component defines the metadata of component. The selector is the custom HTML name we’ll use to include this component. We’ll add a message variable inside of the demo component class and define its type as a string. Inside the ngOnInit method, we’ll give it a default value. ngOnInit is a life cycle method that executes before the component is mounted. We can also use the constructor for this purpose, as they will both give the same result for this application.React vs Angular: An In-depth Comparison

Next, we have created the HTML, where we are using an H1 tag to display the current value of the message variable. The double braces are used to interpolate the value of the message. We’ll also create a form without an action, which consists of a label and an input field of type text. To create a two-way binding, we need to use ngModel which will allow us to change the value of the message variable and then the name property will display the value of the variable inside of the input field. So, before we type anything, it should have the default value Hello written into it.  

Once we include this component inside our main component and run the application, we will see the output as Hello. 

This is an example of Two-way Data Binding, since changing the input immediately reflects on the browser.

I have written these two-sample codes to explain the approach of React and Angular. Notice how the different coding styles can help differentiate between the code written in Angular and React. 

For a beginner or experienced programmer, it is important to get the hang of the coding style of a particular language to develop expertise in it.

Till now we have seen the technical differences of Angular and React. But to understand which technology stack to pursue it is important to gauge your interest in the particular framework or language and its popularity in the real world.  In other words, understand which companies are using that technology. 

Let’s now look at who around the world is using React and Angular.React vs Angular: An In-depth Comparison

  • FACEBOOK – The tech giant Facebook is the founder of React and majorly uses React components in Facebook, which is one of the highest traffic sites. Similarly, it is used in WhatsApp and Instagram which has an even larger user base. 
  • GOOGLE  Google is the founder of Angular. Iuses Angular in several of its internal projects, as well as imany customer projects because of its MVC Architecture. 
  • Sitecore - is a customer experience management company that provides web content management and multichannel marketing automation software. It has a complete Sitecore JavaScript Services SDK for JavaScript developers that enables building full -fledged solutions using modern JavaScript UI libraries like React and Frameworks like Angular. 

This helps us gauge the popularity of React and Angular. Facebook and Google are just two of the most popular companies using these technologies. There are several enterprises around the world that have adopted and benefited from React and Angular. 

So, now that you know that both are equally popular, let us try and understand which one of the two is easier to learn.

Since to learn anything it is important to have a solid foundation, the easier technology to learn would be the one where the prerequisites to learn it are easier. Another important factor is Community Support which is very important when it comes to learning a new technology. A growing and active community plays a major role is helping one master a technology stack.

Learning Curve

  • React – Personally I feel learning React is easy as it is based on JavaScript. If we are well versed in advanced JavaScript concepts, we can do very well in React.

If you want to explore the ways to get started with React, please go through these listed resources which are very useful for a beginner:

  • Angular – The learning curve for Angular is steeper than React, as Angular is a complex and verbose framework. TypeScript may look similar to JavaScript but takes a little longer to learn.  

Beginners should always start with what is easier, and then gradually move towards complex code, so it makes sense to start learning React first and then get into Angular.

I am going to list a few blogs as references, which I think are wonderful resources in the journey of exploring and learning Angular and its concepts. 

Community Support & Updates

Angular releases newer versions or updates every six months. So, in a year, there are two major releases or updates to make necessary changes. Developers have experienced many changes since its release and the current version is version 10.  Angular is supported by huge and active communities of Google.

React is maintained by Facebook and its current version is 16.13.1. Upgrades in React are easier than in Angular. Also, stability is a major concern when it comes to releasing newer versions of Reactsince big companies like Twitter and Airbnb use it. It also has good community support.

Migration

Updates and Migration are also important aspects of any project created in React or Angular. React projects are easy to migrate and update as Facebook developers give regular updates along with breaking changes updates.

With migration projects, we can migrate one part of a page component wise. This ensures that there are no breaks in the other functionalities of a working project. Because of this feature, Facebook has been successful in migrating many of its pages into React components.

Whereas, Angular is not that easy to migrate, as a lot of its libraries have to be used in a single project and because of its two-way binding it is connected to modal state as well. Angular projects are large and complex, and it takes proper planning and timelines to migrate full projects.

When you are migrating your project, there may be a need to add some React code to the site. To learn more about how you would do this, read. 

Let’s see the latest Google Trends to compare the popularity of Angular and React along with stack overflow Trends. 

Google Trends: 

Google Trends

Image Source

Stack Overflow:

Stack Overflow

Image Source

The above graph gives you an idea of the presence and popularity of React and Angular in the present marketReact leads the race because of its simple and easy syntax that makes it more appealing to beginners and companies who are adopting it for small projects. But Angular also has its own unique features which are being used by lots of developers for enterprise level applications. 

Conclusion  

Through this post I have tried to explain some important aspects of React and Angular and the differences between the two. I would recommend that those who wish to master these two technologies, go through the official documentation of Angular and React as it explains a lot of concepts and components in a detailed manner. Going through the official documentation is always a great option to learn any new technology and follow along. At the end I am listing out the links of official sites for learning resources of Angular and React. I am also going to list out few references of important concepts of React and Angular which are very important for a beginner to start with. 

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Jaya Chitteti

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How to Install Angular on Windows

In this article, you will learn how you can install Angular CLI on your Windows machine and use it to create real-life Angular Applications/Projects.As you know, Angular is popularly used to create SPAs (Single page applications). Angular is an in-demand, open-source, and modern web application development framework by Google, as compared to all other Libraries and Frameworks like ReactJs, VueJs, MithrilJs, etc.The reasons behind this are many. Angular provides you full access to use all its sub-packages like routing, Async calls, Security, etc.Introduction — What  you will learnIn this blog, we will cover the installation of Angular on Windows. By end of the article, you will understand how to -Install Node/npm on your machine.Use and install Angular CLI globally.Run Angular CLI commands.Create an initial workspace for the application.Run the Angular application in Browser.We assume you are already aware of the basics of web development including HTML, CSS, and JavaScript. 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For more information on Node.js refer to official docs.Angular requires the latest/stable version of Node.js in order to continue. Go to the official website in order to install Node.js on your machine locally.You can install any version, the current one or latest stable version, as per your need. Just click on the button and it will start downloading the package on your machine. Once downloaded click on the icons downloaded and follow the steps, till the installation is completed. To check the version installed of Node.js you can use the following command in a terminal/console window. —node -vornode — — versionNeed for NPM for Angular development As Node.js serves as Run time environment for the application, similarly NPM(node package manager) is used as a dependency management tool for any JavaScript application. 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To make it easier for the developer, Angular team come up with the easy-to-use tool named Angular CLI. As the name suggests CLI (command line interface) provides a user (developer) friendly interface where you can run commands to make your development life easier and faster. Angular CLI comes with a number of commands available to use from creating a new project, to creating components, creating a routing configuration file, services, and many more.Installation Process of Angular CLITo install the Angular CLI on your machine, open the terminal window and run the following command: npm install -g @angular/cli where -g denotes that CLI is being installed globally to your machine, which means you can create or run any command of CLI anywhere on your machine. Once you run the above command CLI will be installed on your machine, and you can verify the version installed using the following command: ng version To know more about Angular CLI commands, you can refer to this blog which contains a number of commands to use. Creating a Project using Angular CLINow, let’s create our first ever Angular project using Angular CLI. Open your terminal window and type the command below on your machine.ng new hello-world Here ng is our CLI prefix, new denotes that we are creating a new project and hello-world is our project name. You can choose any name you want.After running this command you will find the full architecture of the project in the directory where you run this command. 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Run the application  one with the installation process of Angular application via CLI, it’s time to run the application locally. Angular CLI comes with complete tool-chain/commands for the development of front-end applications on your machine.Run the following command on the terminal (Navigate to the project directory if you are not in that directory).ng serve or ng serve --open The --open (or just -o) option automatically opens your browser to http://localhost:4200/. ng servecommand will serve your application on localhost server which you can check by navigating to your browser with the below URL http://localhost:4200/. You can customise the port as per your requirement. Accessing Angular Web Interfaceng serve command may take a few seconds to run your application, and once completed, you should see a web page similar to the following. And we are done!Now you can make changes in the default component’s template which is app.component.html .Also, moving forward, you can generate a number of components/service/routing files using CLI commands as per your requirements and keep learning.ConclusionIn this blog you have learnt - What is Node/NPM and how you can install and use it,  What is Angular CLI and how you can use it after installing it on your Windows machine, How to create a new Angular project from scratch using CLI commands and run it. Now that you have basic hands-on knowledge of getting started with an Angular application, you can start exploring Angular further. If you have any questions/doubts related to this blog, please let us know in the comment box below...we would be more than happy to help you out!  
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What is NPM in Node JS?

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As of January 2021, the current count is 1,493,231 packages.  NPM is used for building lightweight projects that can be easily shared across multiple development teams without dependencies being shared. It allows free use of resources and installs the dependencies only when needed. Install npm Node/npm can be installed on Mac, Windows or Linux as well. Let’s go through the steps involved in installing it on Mac. The approach should be similar for the other Operating systems. For Linux, refer to this. Navigate to and you will see the download section. Under the download, there is the other downloads link which will display different operating systems. Download the one specific to your Operating System. Double click on the node-v**.**.*.pkg to install the node. It is a simple wizard with straightforward steps. npm is installed with Node.js If you are wondering why we are installing node instead of NPM, this is because Node.js installs NPM along with it. This is evident from the below snapshot. How to check that you have node and npm installed The most common way to check if node or npm is installed is by looking at the terminal. Open terminal and Type in `node -v` and you should see the same version display in the installation wizard. The same applies to npm; i.e. You can type in ‘npm -v’ in terminal. On Versions - A note on versions, npm versions, Node versions and Long-Term Support When we are downloading the node.js from, we have two options; i.e. LTS and Current, both pointing to different versions, and currently on the higher version. LTS stands for ‘long time support’ and Current is the version that has the latest features, and offers support for 6 months. After 6 months, odd-numbered releases will become unsupported and even numbered ones will be given LTS status with support for 30 months. So, for all production applications, one should rely on Active LTS or Maintenance LTS releases. Current can be used for any trainings or by source contributors i.e. library authors.  Use a Node.js version manager Imagine you are working on an Enterprise application for an organization which uses a specific version of Node LTS. Also imagine that there is another app (it could be your pet project) that you are working on, for which you prefer to work on the latest version. But how can we have two different versions of Node in the same machine?  To achieve the same, we have NVM (Node.js version manager). Here is the official site for Mac and Linux users. Windows users can visit this link. Follow the installation steps to install the NVM on your machine.  To verify if NVM is installed correctly, open the terminal and type in ‘nvm --version.’ Type in ‘nvm list’ to display all the node.js versions that are installed on your machine. For now, you should be seeing only one version. Say you want to install an outdated version of Node.js, say 12. Type in ‘nvm install 12’ in terminal and it should install the 12 version of Node.js for you.  Now, type in ‘nvm list’ to see both the versions of node that are available for use. To switch to a specific version of node, type in ‘nvm use 12’. To check if it is the active one, type in ‘node -v’. Now you are good to go ahead with your project for that specific version of node.js. ConclusionNPM is one of the world's largest software registries. The Source contributors or developers are from across the world, and use npm to share or use packages. Many organizations/firms use npm for private development as well. NPM has 3 components i.e. Website, Command Line Interface and Registry.  We used the website to identify the package for ‘date format’ above. We learnt to set up private packages as well alongside public. The Command Line Interface is run from the terminal and is used by most of the developers, and the Registry is the public database of the JavaScript software.  
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What is NPM in Node JS?

If you have ever worked with Node or any JavaSc... Read More

Node.Js - Net Module

Node.js has a ‘net’ module which provides an asynchronous network API for creating stream-based TCP/IPC servers and clients. It can be accessed using: const net = require('net');  To create a TCP/IPC based server, we use the createServer method. var server = net.createServer(); The ‘server' object is of type net.Server. Let’s explore a few properties, events and methods on this class. First and foremost, the method needed is ‘listen’ which starts the server for listening to connections in async, firing the ‘listening’ event. server.listen(9000, () => {    console.log('opened server on port: ', 9000);  }); To find out on which address a server is running, we can use the address() method on the net.Server instance. If we need to log the port on which the server is running, then we can get this info as well without hardcoding. server.listen(9000, () => {    console.log('opened server on %j', server.address().port);  }); The first parameter of listen is the port in which the server starts listening, and a callback which gets called once it has started listening. A few of the common errors raised are:  ERR_SERVER_ALREADY_LISTEN – server is already listening and hasn’t been closed. EADDRINUSE – another server is already listening on the given port/handle/path. Whenever an error happens, an ‘error’ event is raised. We can hook to it and capture the errors accordingly. server.on('error', (e) => {    if (e.code === 'EADDRINUSE') {      console.log('Address in use, retrying...');      setTimeout(() => {        server.close();        server.listen(PORT, HOST);      }, 1000);    }  }); Whenever a client connects to this server then a 'connection' event is raised and in the callback we can get hold of the client object for communicating data. server.on("connection", (socket) => {    console.log("new client connection is made");  }); The second parameter is actually a callback which has the reference to the connection object, and the client object is of type ‘net.Socket’. To get the details like address and port, we can rely on remoteAddress, and remotePort properties respectively.   server.on("connection", (socket) => {    console.log("Client connection details - ", socket.remoteAddress + ":" + socket.remotePort);  }); Let’s assume that we are developing an application server like bot which needs to take inputs from clients and respond to the client. We can get hold of the client object and send messages to it from the server. As soon as the client is connected, we can send a sample return message on successful connection. server.on("connection", (socket) => {    console.log("Client connection details - ", socket.remoteAddress + ":" + socket.remotePort);    socket.write('SERVER: Hello! Connection successfully made.');  }); Now if there is any data being sent by client, we can capture that data on the server by subscribing to ‘data’ event on the client socket object.  socket.on('data', (data) => {    console.log(data.toString());// since data is streamed in bytes, toString is used.  }); Some of the most commonly used events on ‘net.Socket’ are data, error and close. As the names suggest, data is for listening to any data sent, error when there is an error happens and close event is raised when a connection is closed which happens once. Here is an example in server.js file: const net = require('net');  var server = net.createServer();  server.on("connection", (socket) => {    console.log("new client connection is made", socket.remoteAddress + ":" + socket.remotePort);    socket.on("data", (data) => {      console.log(data.toString());    });    socket.once("close", () => {      console.log("client connection closed.");    });    socket.on("error", (err) => {      console.log("client connection got errored out.")    });    socket.write('SERVER: Hello! Connection successfully made.');  });  server.on('error', (e) => {    if (e.code === 'EADDRINUSE') {      console.log('Address in use, retrying...');      setTimeout(() => {        server.close();        server.listen(PORT, HOST);      }, 1000);    }    else {      console.log("Server failed.")    }  });  server.listen(9000, () => {    console.log('opened server on %j', server.address().port);  }); ‘net’ module also has another class type net.BlockList. This helps in controlling or disabling the inbound or outbound traffic based on rules from any specific IP addresses, IP ranges, or IP subnets. Here is an example snippet from the documentation: const blockList = new net.BlockList();  blockList.addAddress('123.123.123.123');  blockList.addRange('10.0.0.1', '10.0.0.10');  blockList.addSubnet('8592:757c:efae:4e45::', 64, 'ipv6');  console.log(blockList.check('123.123.123.123')); // Prints: true  console.log(blockList.check('10.0.0.3')); // Prints: true  console.log(blockList.check('222.111.111.222')); // Prints: false  // IPv6 notation for IPv4 addresses works:  console.log(blockList.check('::ffff:7b7b:7b7b', 'ipv6')); // Prints: true  console.log(blockList.check('::ffff:123.123.123.123', 'ipv6')); // Prints: true Now that we have the server up and running, we can build a client to connect to the server and start sending bi-directional data. This client could be another node.js application, java/c# application working with TCP sockets, asp.net MVC application talking to node.js TCP server or any other client application. But that client application should have TCP based communication mechanism support. Since we are talking about ‘net’ module, let’s build the client application as well using net module. Moreover, it supports TCP based communication as well. 'net’ module has a factory function called ‘createConnection’ which immediately creates a socket and establishes a connection with the server running on the specified port.  Let's create another client.js file and create a connection. const net = require('net');  const client = net.createConnection({ port: 9000 }, () => {    console.log('CLIENT: I connected to the server.');  }); The first parameter contains the details of the server. Since we are running the server locally, providing the port number would suffice for us as the host default address is localhost for TCP connections. The second parameter is the callback called once the connection is made successfully with the server. The returned value is of type net.Socket which we have learnt about earlier. Let’s hook to ‘data’ event and console log the information sent by the server. client.on('data', (data) => {    console.log(data.toString());    client.end();  }); Here we are not persisting the TCP connection and ending it once we receive a message from the server. We can subscribe to close event and handle any clean up needed. client.on('end', () => {    console.log('CLIENT: I disconnected from the server.');  }) The output on the client terminal has to be:  CLIENT: I connected to the server.  SERVER: Hello! This is server speaking.  CLIENT: I disconnected from the server. Output on server terminal will be: new client connection is made ::ffff:127.0.0.1:51680  CLIENT: Hello this is client!  client connection closed. In case we want to continue the client instance till the server is alive, we can comment out the ‘client.end()’ call. Any message in the terminal can be processed and sent to the server. For reading the text from terminal we use the readline module. Here is a complete example: const net = require('net');  const readline = require('readline');  const rl = readline.createInterface({    input: process.stdin,    output: process.stdout  });  const client = net.createConnection({ port: 9000 }, () => {  console.log('CLIENT: I connected to the server.');    client.write('CLIENT: Hello this is client!');  });  client.on('data', (data) => {    console.log(data.toString());    //client.end();  });  client.on('end', () => {    console.log('CLIENT: I disconnected from the server.');  })  rl.on('line', (input) => {    client.write(`CLIENT: ${input}`);  }); Both client and server now can communicate. When we type any text in client terminal, that is communicated to the server, and the server can respond back to the client via terminal.  ConclusionWebsockets help in creating a full-duplex connection for sending messages from client to server and vice-versa. Some of the real-time use cases that you may be familiar with are chat apps, IoT devices and so on. The Node.js net module helps you to create a server application easily, which can communicate to any type of client application like a web browser, mobile app, IoT device, Node.js client, or anything that knows TCP where the messaging need is bi-directional with streams. ‘net’ module can be used to communicate among child processes within a node.js server as well. 
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Node.Js - Net Module

Node.js has a ‘net’ module which provide... Read More