Companies and brands are willing to invest in websites and apps that are quick, dynamic, and efficient as a direct result of the increased momentum that digitization is obtaining in the sector in the contemporary day. Despite this, selecting the appropriate development technology for web app development might be difficult due to the vast availability and accessibility of several development technologies. Although full-stack, front-end, and backend development have been at the forefront of web development for quite some time, there is a new star on the rise and its name is the MEAN stack.

The MEAN stack is essentially an open-source technology that is comprised of four technologies that are based on JavaScript. These technologies include MongoDB, ExpressJS, AngularJS, and Node.js (MEAN). You may take advantage of the benefits offered by a variety of different domains for the development of web applications and dynamic websites if you understand and grasp MEAN stack.

In this piece, we are going to discuss the MEAN stack interview questions that are asked the most often since the need for developers who are proficient in the MEAN stack is rapidly increasing.

Therefore, let’s not waste any more time and go right into it.

Top MEAN Stack Developer Interview Questions & Answers

1. What is the function of the MongoDB database?

A document-oriented database manager, MongoDB was developed specifically for the purpose of storing large amounts of data. It also incorporates the idea of collection and documentation into its operation, saving data in the binary JSON format. MongoDB is a NoSQL database that is cross-platform. It has high performance, high scalability, and flexibility, all of which allow for seamless querying and indexing.

2. What are some of the goals of using ExpressJS?

ExpressJS is a web application framework that was developed to support and host projects written in the Node.js programming language. It is a framework that is open-source and can be downloaded under the MIT licence. ExpressJS is responsible for workflow management between the front-end and the database, and it ensures that data is transferred in a streamlined and protected manner. It boasts excellent functionality for handling errors and web design, which helps to optimise the process of developing websites.

3. What are some of the applications for AngularJS?

Google is the organisation responsible for maintaining the open-source front-end web application development framework known as AngularJS. It gives web developers the ability to use HTML as their template language and extend HTML syntax in order to represent the components of a web app in a way that is both clear and accurate.

4. What is the purpose of the Node.js programme?

Node.JS is a JavaScript framework that is open-source, cross-platform, and single-threaded. It is used for the development of server-side applications as well as networking applications. It serves as the framework upon which the MEAN stack is built. Node.js made use of a number of different programming languages, including JavaScript, C, and C++. Because it comes with its own built-in web server, Node.js makes it easier to successfully deploy the MongoDB database and the cloud application that goes along with it.

5. What are some IDEs that are commonly used to build Node.JS?

The following is a list of the most widely used integrated development environments (IDEs) for Node.JS development:

  • Atom
  • Cloud9
  • Eclipse
  • Komodo IDE
  • JetBrainsWebStorm
  • JetBrains IntelliJ IDEA

6. What is Mongoose?

Mongoose is an Object Document Mapper (ODM). This means that by using Mongoose, you can define objects with a strongly typed schema that can then be mapped to a MongoDB document. It gives you a way to model application data using schemas. Mongoose has many built-in features, such as typecasting, validation, query building, business logic hooks, and more.

7. Define DATA modeling?

The term “data modelling” appears frequently in discussions pertaining to Mongoose and MongoDB. The creation of a data model for the data that is currently available in order to prepare it for storage in a database is the process that is referred to as “data modelling.” A data model is a conceptual representation of data objects, the relations among various data objects, and the rules that define those relations. A data model also includes the data objects themselves.

The data can be represented visually with the assistance of data modelling, which also helps to enforce business rules, regulatory compliances, and government policies on the data. It is implemented to ensure consistency in naming conventions, default values, semantics, security, and the quality of the data. Additionally, it is implemented to safeguard against data loss.

8. Define Scope in JavaScript.

Every function in JavaScript has its own “scope,” which can be thought of as a collection of variables and rules that define how that function’s specific name can access those variables. You can only access the variables that are local to a function by using the code that is contained within that function. Although the names of variables contained in a particular scope must be distinct from one another, scopes can be contained within one another. In this particular scenario, the code that is part of the innermost scope is able to access the variables that are part of either of the other scopes.

9. Can you explain the difference between a binary search and a linear search?

A linear search goes through each item on a list one at a time, without skipping ahead in the sequence. Therefore, in terms of complexity, it is categorised as an O(n) search, which indicates that the amount of time required to search the list grows proportionally with the increase in the list’s size. On the other hand, a binary search begins in the middle of a list rather than at the beginning. The purpose of this search is to determine whether the value of the item is higher than or lower than the value that is desired.

This also decides where in the list the value will fall, either in the first or the second section of the list, depending on which section it falls into. It is classified as an O(log n) search, which indicates that the number of search operations grows more slowly than the list itself. This indicates that the complexity of the search is relatively low. This is due, in large part, to the fact that the search space is cut in half during each operation.

A linear list does not have any such prerequisites, in contrast to binary search, which needs the input data to be sorted before it can be used.

10. Explain the key differences between jQuery, AJAX, and Node.js.

jQuery, Node.js, and AJAX are all advanced implementations of the programming language JavaScript. On the other hand, there are a number of key distinctions between them.

While AJAX, also known as Extensible Markup Language, is a client-side platform, Node.js is a server-side platform that is used for developing client-server applications. The client-side scripting technique known as asynchronous Javascript and XML is primarily employed for the purpose of rendering the contents of a page without first refreshing that page. The primary purpose of using AJAX is to display dynamic content. AJAX, DOM traversal, and looping are all enhanced by the use of jQuery, which is a JavaScript module. It comes packed with a wide variety of helpful functions that can be used to make development of JavaScript easier.

11. Define Dependency Injection.

Dependency Injection is a concept in software design that frees you from the constraints of client consumption while still enabling you to use or inject a service in any way you see fit. By taking this action, you will effectively stop the client from modifying its dependencies whenever the underlying service undergoes a change. Dependency injection’s primary objective is to decouple the process of creating clients’ dependencies from the behaviour of those dependencies, allowing for the development of programmes with a greater degree of modularity. The components of a programme that is only loosely coupled will typically make use of the functionality that is defined by the program’s interfaces without having any prior awareness of the classes that are used for the program’s implementation. Changing the components of an application that are responsible for implementing the interfaces that define an application’s features enables dependency injection, which gives you the ability to modify or “tweak” the behaviour of an application.

12. Define Containerization.

The process of enclosing an application inside of a container and running it inside of its very own operating environment is known as containerization. Containerization is an alternative to the traditional hypervisor-based machine virtualization. With containerization, an operating system is not replicated for each individual virtual machine; rather, it is made available to all of the containers at the same time. When an application is loaded into a virtual machine, it is possible to run the application on any physical machine that is suitable without having to worry about the application’s dependencies.

13. What purpose do Indexes serve in MongoDB?

Indexes are utilised in MongoDB to support and facilitate the execution of queries in a manner that is both effective and efficient. In the absence of indexes, MongoDB is forced to carry out a process known as a collection scan. This requires the database to read each document contained within a collection before selecting the documents that best answer a query. However, if each query has an appropriate index assigned to it, MongoDB can use the index to limit the number of documents it has to inspect. This is accomplished by using the query’s appropriate index.

14. What is the difference between Classes and Interfaces in TypeScript?

Both object-oriented programming and type-checking are fostered by TypeScript’s use of classes and interfaces, which are structures. Classes and interfaces. An interface is a collection of related properties and methods that describe an object. In contrast to a class, which acts as a blueprint from which you can create a group of objects that share the same configuration (properties and methods), an interface describes the object as a whole. On the other hand, an interface does not supply implementation or initialization for the objects it describes.

Typically, a class will define what an object ought to look like and how it ought to behave, and in accordance with this, it will generate and then implement a blueprint by initialising the class properties and defining the class methods. Classes are utilised during each and every stage of the coding process. On the other hand, an interface is a type of virtual structure that only exists within the confines of the TypeScript programming language. When it comes to type checking, the TypeScript compiler relies completely on interfaces.

15. Define “Decorators” in TypeScript.

A “Decorator” is a unique kind of declaration that can be used in TypeScript. This kind of declaration is typically appended to a class declaration, method declaration, accessor declaration, property declaration, or parameter declaration. Decorators are functions that take their target as an argument in order to operate properly. They make it possible for you to execute arbitrary code around the target execution or even replace the target entirely with a new definition.

16. What is meant by “Callback” in Node.js?

A callback is the asynchronous equivalent of a function in the Node.js programming language. Callbacks are extremely important to Node.js, and they are invoked once an activity has reached its conclusion or been finished. For example, let’s assume a function that is designed for reading files can begin reading files and then immediately return control to the execution environment so that the next instruction can be carried out. This would make it easier for the programme to carry out the instruction.

After the file I/O operation has been finished, the callback function will be activated, and the contents of the file will be passed as a parameter to it. This ensures that the file I/O will proceed without being blocked or requiring waiting time. Because of this feature, Node.js is able to process a large number of requests without pausing to await the outcome of any function, which contributes to the language’s high degree of scalability.

All of Node’s application programming interfaces (APIs) are designed to be able to support callbacks.

17. Define Cross-site Scripting (XSS).

The term “cross-site scripting,” or “XSS,” refers to a type of client-side code injection attack in which malicious scripts are run in a web browser by injecting malicious code into a legitimate web page or web application. This type of attack is known as “client-side scripting.” It is also possible for it to happen when a person clicks on a link that they do not trust, which then sends cookies and other sensitive information to the attacker.

When you visit a website or app that runs malicious code, you are putting yourself at risk of being attacked. As a result, the user’s browser can be infected with malicious scripts through the website or web application that they are using.

Forums, message boards, and even web pages that encourage users to comment are among the most common vehicles used in cross-site scripting attacks.


The following is a list of the most important MEAN stack developer interview questions that we have. Interview questions and answers for the MERN Stack developer position. We really hope that this information helps you ace your upcoming MEAN stack interview!

To become a mean stack developer, it is important to become proficient in all of the languages and tools used in the full stack. The path to becoming a full-stack developer is one that is fraught with difficulty but also rich in potential rewards. If one has the desire to pursue it, this is truly one of the best careers out there to pursue because of the creative and financial opportunities that come with it. Check out the full-stack software development PG course offered by upGrad if you’re interested in developing intelligent chatbots, fintech wallets, and other applications and have the drive to do so.

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