Node JS Tutorial: Learn Node JS from Scratch

Websites and applications that require any sort of consumer interaction need a backend server. These servers have to be built on asynchronous programs that are scalable and efficient. One of the most popular open-source platforms for creating servers and applications is Node.js. It enables building single-page websites and applications, chatbots, and data-driven platforms like Netflix and LinkedIn. This blog explains what Node.js is, its various features, setting up and creating applications on nodes.

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What is Node.js?

Built by Ryan Dahl in 2009, Node.js is a cross-platform JavaScript runtime environment. Powered by a V8 engine, Node.js can execute JavaScript code outside a web browser. Also, being a server-side platform, it grants restricted access to users. Only the authorised users can access all the functions, whereas the other users can only see limited information. As the name suggests, server-side programs run and execute codes for the server-side and not the client-side.

Node.js uses Google Chrome’s Javascript to build fast network applications. 

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Read: Difference Between Node JS and React JS

What are the Various Features of Node.js?

The following are some of the significant features of Node.js:

• Scalable:- One of the most desirable attributes of software applications is scalability. It means the ability to scale or increase its capacity and functionalities to accommodate the needs of various users. Even though scalable software undergoes multiple changes based on the user’s needs, its crux remains the same. It can handle numerous requests parallelly. Hence, Node.js allows the programmers to create several versions of an app, each with distinct features to cater to the target audience’s requirements
• Single-threaded:- The Node.js architecture uses a single thread to loop events. It means that the platform requires only a single sequence to execute a set of instructions. It facilitates the execution of a single command at a time. The applications created on node.js use a single-thread architecture. It handles several clients simultaneously like HTML, ASP.NET, and JSP. Whenever the clients send a request to the server, it reaches an infinite loop in the web server along with other clients’ requests. The web server picks one request from multiple requests at a time and then picks up one thread from the pool. The thread is then assigned to the client request that reads, processes, and performs other operations.

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• Timely execution:- Another significant feature of node.js is its quick execution. Since the platform uses the V8 JavaScript engine, the code runtime is fast.
• Asynchronous and event-driven:- Node.js is an asynchronous event-driven platform, indicating that different processes or functions operate independently. The functions are not synchronised. The node.js server does not wait for the application programming interface (API) to send the data. As soon as the server accesses one API, it processes the other request. To track the responses of the API requests, it uses events as a notification mechanism. It has three main elements – event queue, event loop, and thread pool.
• Compatibility with various platforms:- Node.js can be operated across various platforms, including Windows, Linux, Mac, and mobile devices.
• No buffering:- In node.js, the data does not buffer. In fact, the end data is received in chunks.

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What are the Various Uses of Node.js?

Node.js is a popular choice for building applications because of its scalability and asynchronous attributes. The following are the most common uses of Node.js.

• IoT Applications:- Since IoT applications have to manage dynamic data, they require frameworks to handle heavy data flow. Node.js being a scalable software, is capable of managing heavy data flow.
• Data Streaming Applications:- These are audio or video streaming applications in which large amounts of data are sent in small packages. Node.js has in-built modules that support data streaming.
• Real-time Applications:- A classic example of such an application is a chatbot in which a user sends messages and receives immediate responses. Due to its high speed and scalability, Nodes.js is the ideal platform for creating real-time chatting or messaging applications.

Useful Read, Top 41 Node.Js Interview Questions & Answers You Need To Know in 2022

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Setting up Node.js environment

You can set up a local environment to use Node.js on a desktop with the help of two elements; a text editor, and the Node.js binary installable.

• Text editor:- You require a text editor like Windows Notepad, EMACS, Epsilon to type the program. However, you need to ensure the text editor is compatible with your operating system and is updated to the latest version. You can create source files with the text editor with the extension “.js”.
• Node.js Runtime:- The source code is in JavaScript, interpreted by the node.js interpreter. You can use the Node.js binary installable for Windows, Mac, and other operating systems.

How to Create the First Application in Node.js?

Creating an application on Node.js has three steps; importing the required modules, building a server, and reading requests and returning responses.

• Import Required Module:- To load the required module in Node.js, you must use the ‘require’ directive. For instance, if you have to import the HTTP module, you will have to type require (“http”).
• Creating Server:- Since Node.js is a server-side module, you have to create a server using the loaded module. As seen in the above example, you can use http.createServer() to build a server. You need to go to the Node.js command and open a new prompt to start the server. After typing cd desktop on the command prompt, you can execute the main.js or the source file on the desktop.
• Reading Requests:- After a server is started, you have to request the created Node.js server to test it. For that, you need to open http://127.0.0.1:8081/ in a browser. You will see the text “Hello World”, which means the server is accepting requests. However, if you make changes in the source file later, you need to rerun the Node main.js command.

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REPL Terminal in Node.js

Node.js comprises The Read Eval Print Loop (RELP), a computer environment similar to the Linux shell of the Windows console. It helps in performing various experiments with Node.js and debugging JavaScript codes. You enter a command in the environment and receive output in the interactive mode. The following are the four essential tasks of REPL Terminal:

• Read:- RELP reads the input given by the user and takes it through the JavaScript and data structure to store it in memory.
• Eval:- Another critical task is to evaluate the data structure.
• Print:- After the evaluation, RELP helps print the result.
• Loop:- In Node.js, the above command works on loop until the users have to press ctrl-c twice.

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Here are some of the REPL commands in Node.js

• Ctrl+C once terminates the ongoing command. Twice, it terminates tye Node REPL.
• Tab keys tell you the list of all current commands.
• .help provides you with a list of all commands.
• .break offers the developer an exit from multiline expressions.
• .load filename allows you to load the file content in a REPL session.

Event Loops in Node.js

In Node.js, callbacks are asynchronous functions that you have to execute after completing a particular task. Nearly all the application programming interfaces in Node.js require callbacks. The event loops in Node.js use the callback function. When the node server starts, the loop waits for any event to occur. After it listens to an event, the loop triggers the callback function.

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Conclusion

Node.js is a highly-scalable platform with asynchronous functions. Leading companies like Amazon, Netflix, Paypal, LinkedIn, Reddit and others use Node.js for its backend development, chatbots, and other operations. 

If you are interested in coding, programming, and software development and wish to build a career in this field, it is desirable to have the know-how of Node.js. The best way to learn about Node.js from scratch is to pursue a degree in Computer Science. You can enrol in the Masters of Science in Computer Science Course on upGrad offered by the Liverpool John Moores University.

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