Top 10 Node js Interview Questions

JavaScript demand is skyrocketing. There are many aspiring professionals who wish to take this opportunity and build a career in this web development arena. Therefore, Node js is among the JavaScript technology which is seeing high growth in recent times. Not many businesses know what are Node.js best practices and what can be achieved if you follow them. There are so many questions that need an answer. So, we decided to burst this bubble of the popularity of Node js by addressing the most common Node.js interview questions and answers in our blog. We aim to make this blog an insightful and meaningful one. So, without much ado, let’s get to the point.

In this blog, we intend to answer the top 10 Node.js interview questions that are always spurious among developers. We will start with what is Nodejs, followed by Node JS interview questions, and know all the advantages that would help developers to better understand the technology and deliver the best Node. js-based applications.

1. A Brief Intro to Node.js

There is a lot of fuss about Node.js on what it is? Whether it is a framework or it is a tool or what it is. To give a brief about Node.js, Node.js is a server-side runtime environment based on Chrome’s V8 JavaScript engine. There is a cross-platform environment that helps in developing adaptable and flexible server-side applications using JavaScript. Node is event-driven, Asynchronous I/O event-driven.

Speaking of the features, Node.js is a single-threaded, event-based architecture and non-blocking I/O models are used in JavaScript. The architecture is made up of Google Chrome’s V8 engine, which is written in C++ and Libuv language. It works on I/O-based events, event loops, and thread loops across several platforms. Despite the fact that Node.js is written in Libuv, it may be used in plain JavaScript code.

2. Most Frequently Asked Node JS Interview Questions

Most Frequently Asked Node.JS Interview Questions

2.1 How Does Node JS  Work? Which Types of Apps are Developed Using Nodejs? 

The first and foremost question of Nodejs revolves around how does Nodejs work. To answer that, you must know that Nodejs works on a virtual V8 environment that uses JavaScript as its scripting language to achieve high output using non-blocking I/O and a single-threaded event loop. Node.js works in an event loop which is provided by a special library called “Libuv,” as per the Node.js developers. When asked about Nodejs functioning, you must also know that Node.js processing architecture is heavily influenced by the Javascript event-based approach and the callback mechanism. 

2.2 What is NPM & Functionality?

What is NPM & Functionality?

When it comes to Node, there is a special Package handler called NPM- Node Package Manager is in charge of handling all of Node.js’ packages and modules. NPM manages the majority of functions such as if you want to find online repositories for node.js packages and modules then use the function. Also, if you want to install Node.js packages and maintain their versions and dependencies, you can do it easily using a command-line interface.

2.3 How Would You Differentiate Between Frontend and Backend Development?

How Would You Differentiate Between Frontend and Backend Development?

Such questions are asked just to check the roots and the understanding of the concept. So for your answer, you must know that when we’re developing a user interface of an application it is referred to as the frontend. While on the other hand, the server-side of a program is referred to as the backend. The front-end side of the application can be used by users to see and interact with it as part of a web application. Everything else that occurs behind the screens is included in the backend category. It usually refers to everything related to a web application’s aesthetic appearance. To serve requests, it usually contains a web server that interfaces with a database. This part of the request is handled by Backend.

If you are asked what is Node Js a backend or frontend development language? You must answer that Nodejs is a backend development programming language that has JavaScript as a core function.

2.4 Differentiate between Node.js vs Ajax

Differentiate between Node.js vs Ajax?

The primary distinction between Node.js and Ajax is that Node.js is a server-side JavaScript while Ajax is a client-side technology. Ajax is a client-side scripting approach and is mostly used to update or alter the contents of a webpage without having to reload it. Whereas Nodes.js is a server-side framework for constructing client-server applications.

2.5 How Would You Define the Term I/O?

How Would You Define the Term I/O?

Any program, activity, or device that acts as a mediator to transfer data to or from one media to another is referred to as I/O- input-output. Every transfer is a result of one medium’s output and the input of another. For an input/output. In this way, a physical device, a network, or files within a system can be used as the medium between your internal system and external devices.

2.6 What Makes Asynchronous and Non-Blocking Different Concepts From Each Other?

Nonblocking replies instantly if the data is accessible, and if it is not, it simply provides an error. Asynchronous does not react immediately. Asynchronous increases efficiency by doing activities quickly while waiting for a response; in the meanwhile, additional tasks can be completed. Non Blocking prevents any execution from being halted, and it fetches data rapidly if it is accessible. Nonblocking I/O is the polar opposite of blocking I/O. They’re comparable, however asynchronous is utilized for a larger variety of tasks, whereas non-blocking is generally used for I/O.

2.7 Define Callback Function in Node.js

Define Callback Function in Node.js

In node.js, the callback function is used when there are multiple server requests. If you have a huge system with many files that would take more than expected time for a server to read Then you have a callback method. You don’t want the server to make way to requests so, you may utilize the callback method. The call back function lets the server take care of any pending requests first, then call a function after they’re done. Callback functions are a big part of Node.js. Node’s APIs are built with callbacks in mind.

2.8 What Do You Understand About Event Loop in Node.js and Its Functioning?

One of the most talked-about aspects in Node.js is event Loop. So what is the event loop in Nodejs? An event loop in Node.js manages all of an application’s asynchronous callbacks. It is one of the most significant components of Node.js and the cause for the non-blocking I/O in Node.js. Since Node is an event-driven language, there is always a listener that performs the callback function whenever an event occurs. 

Node.js executes the event loop whenever methods like setTimeout, http.get, and fs.readFile are used, and then continues with the rest of the code without waiting for the output. When the operation is complete, Node.js receives the output and calls the callback function. This is why all of the callback functions are put into a loop in a queue. They are carried out one by one after receiving the response.

 In simple terms, when you want to process or handle requests coming from external sources then you need to convert them into callbacks. There are invocations occurring from the event loop which can help the nodejs function to switch from one request to another.

2.9 Explain the Purpose of Express JS Package

To know the function of the Express.js package, you must first know what express.js is and what importance it holds in Nodejs. Express.js is a flexible web application framework in Node.js with a broad array of features to develop all types of mobile and web applications. Express.js is a Node. js-based framework for managing the flow of data between the server and server-side web applications. It’s a lightweight and adaptable framework with a variety of capabilities for online and mobile app development. Connect, a Node.js middleware module serves as the foundation for Express.js. In order to communicate with Node.js, the connect module uses the http module. As a result, you can simply combine Express.js with any connect-based middleware module.

2.10 What Does Event-Driven Programming Mean?

Whenever you build your application in a way that responds to events then you have used event-driven programming. It goes as the name- event-driven programming means the programming driven by a sequence of events. Like if we run a callback function that is registered to the element for that event when an event happens, you respond by clicking or keypressing. When an event is triggered, a call-back function that has previously been registered with the element is called. The majority of event-driven programming follows a publish-subscribe approach. This makes the process faster and more interactive. 

3. The Advantages of Node.JS

The Advantages of Node.JS

Some of the most appealing features of Node.js is the ease with which developers can grow applications both horizontally and vertically. By adding extra nodes to the current system, the applications may be grown horizontally. Starting to use Node.js on the backend becomes considerably easier for them. 

Learning Node.js is simpler, and working with it takes less time. Node.js programmers may use a js runtime environment to create both the front-end and back-end web applications in JavaScript. Because the runtime environment provides non-blocking I/O operations, the performance of code execution is also improved. NPM robust package management may be used to detect and install project dependencies.

Nodejs is quite competent when it comes to web app development and hence we know there are developers(both experienced as well as amateur) who want to try their hands in Nodejs development. 

4. Conclusion

From this entire blog, we believe that we have helped you gain insights from our share of information and knowledge. Now you can pick the pace and grasp all the questions and be prepared for the interview. These useful and important technology questions will help you prepare and crack your dream job. For developers from the Node.js community, there is a large scope and vacancies that will amplify your professional career. Node.js is more beneficial to developers than companies. You can either hire developers from the Node.js development company or hire Node.js developers by asking some of these relevant Node JS interview questions.

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Itesh Sharma

Itesh Sharma is core member of Sales Department at TatvaSoft. He has got more than 6 years of experience in handling the task related to Customer Management and Project Management. Apart from his profession he also has keen interest in sharing the insight on different methodologies of software development.


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