MEAN STACK Interview Questions [WITH EXAMPLE ANSWERS]
Last updated on 05th Jun 2020, Blog, Interview Questions
1. What is MEAN Stack?
2. What is MongoDB?
MongoDB is a document-oriented database that is used to store large amounts of data. With its scalability and flexibility for querying and indexing, it is characterized as a NoSQL database.
3. What is ExpressJS?
ExpressJS or Express is the essential and moderate web framework of Node.js used for the applications, websites, and backends. It is free and open-source framework available under the MIT license.
4. What is AngularJS?
5. Explain Node.JS.
Node.js is a server-side programming language used to build flexible programs. It has several advantages over other server-side languages, the most notable of which being non-blocking I/O
6. Explain key features of Node.JS?
- Fast in Code execution
- Single threads are however extremely ascendible
- A Library Java Script is used by the Node.js
- No Buffering
7. What is IDEs which can be used for a Node.JS development?
The most general types of IDE’s that can be used for a Node.JS development applications are:
3. JetBrains IntelliJ IDEA
4. Komodo IDE
8. Describe the benefits of utilizing Node.js.
- High Performance
- Non-Blocking and Asynchronous
- NPM (Node Package Manager)
- Single Language
9. How can you assess the REPL and Node.Js?
REPL is acronym for reading Eval Print Loop. It also assesses the datasets and lastly depicts the findings. It is important to note REPL provides the climate that is quite similar to Linux Shell. REPL is associated with execution of below-mentioned tasks.
1.Print: It is associated with the printing the results that are derived from a command.
3.Loop: It would be continue to twist the command unless user makes use of Ctrl+C.
10. Is Node.Js just dependent on single thread?
Yes, Node.js can run only in a single thread. However, it is important to understand that the Node.Js architecture is only a concept. It uses callbacks and events in addition to being involved in a single thread mechanism to meet a variety of demands. It is crucial to remember that Node.Js has an efficient design.
11. Explain the working mechanism of Node.Js.
Node.js operates on an event-driven, non-blocking I/O model, making it highly efficient for building scalable and responsive applications. At its core is the event loop, which continuously listens for events, executes callbacks when events occur, and handles asynchronous operations without blocking the main thread.
12. Explain feature of call back from perspective of Node.Js.
Node.Js makes extensive use of a callbacks which enables it to trigger it at execution of given task. In this context, it is important to note that majority of the APIs of the Node.Js is written in such manner that it supports a feature of callbacks.
13. Differences between AJAX and Node.Js.
|It enables web pages to update content dynamically without requiring a full page refresh.||As a python language is flexible, one can simply do the analysis of data.|
|It is the memory computation.||It allows developers to build server-side applications, including web servers, APIs, and other networked applications.|
|AJAX is primarily used for enhancing the user experience by fetching or sending data to the server without reloading the entire web page.||Node.js is used to handle server-side logic and manage server resources.|
14. Define Event Emitter of Node.js.
The event module that is found in a Node.Js would enable the management and creation of bespoke events. It is significant to note in this regard that the event module has a class of game emitter that may be used to manage and raise the custom events.
15. What is the NPM of Node.js?
The NPM stands for Node Package Manager. It is associated with two main functionalities which are listed below:
1.It usually works as command-line utility to install packages. It also carries out a version management and dependency management of different Node.Js packages.
2. It also works as online repository in the case of a Node.Js packages. These are also present in .org file of Node.Js.
16. What is “non-obstructing” in node.js?
17. What type of request that is utilized as a part of node.js to import outside libraries?
Summon require is used to bring in external libraries, like as “var http=require (“http”)”. This will stack the http library and a single protest delivered via the http variable.
18. Define Typescript.
19. What are the upsides and downsides of Node.js?
- Crawlers get full-rendered HTML reaction, which is significantly SEO well disposed of instead of solitary page application or web sockets application that keep running over the Node.js.
- Any concentrated CPU calculation will be square node.js responsiveness, so strung stage is the superior approach.
- Using social database with the Node.js is viewed as a less good
20. What is CORS?
CORS stands for “Cross-Origin Resource Sharing.” It is security feature implemented by a web browsers that restricts web pages from making a requests to a different domain than the one that served a web page. CORS is enforced by default in a modern web browsers to prevent malicious websites from an accessing sensitive data on the other domains.
21. What advantages come from using node.js?
- Generally quick
- Great simultaneousness
- Asynchronous everything
- Almost never pieces
22. Explain the two sorts of API works in Node.js.
- Asynchronous, non-blocking capacities
- Synchronous, blocking capacities
23. What is Static Typing?
Static typing is a programming language feature that enforces strict type constraints on variables, function parameters, and return values at compile-time (or before the code is executed), as opposed to dynamic typing, which checks types at runtime (while the code is running).
24. What are the different ways to deploy a MEAN stack application?
Deploying on cloud platform: Cloud platforms like a Heroku, AWS, or Microsoft Azure offer simple and scalable deployment options for a MEAN stack applications.
Using containerization: Containerization with tools are Docker allows developers to package application and its dependencies into a container, ensuring consistency and portability across the different environments.
Deploying on a traditional server: For on-premises or dedicated server deployments, developers can use the web servers like Nginx or Apache to host and serve MEAN stack application.
25. How does Node.js function?
26. What is the term I/O?
I/O, which stands for information and yield, can refer to anything not related to an application. Upon starting the application, it will be loaded into the machine’s memory to run the program.
27. What does “occasion-driven programming” refer to?
In PC programming, occasion-driven writing computer programs is the programming worldview in which stream of the program is controlled by the occasions like a messages from different projects or strings.
28. What is REPL?
REPL stands for “Read-Eval-Print Loop.” It is an interactive programming environment that allows developers to interact with a programming language by entering code, which is then immediately executed, and the results are displayed.
29. What are the security considerations for MEAN stack applications?
Security is the critical aspect of MEAN stack application development. Some security considerations are include:
- Implementing robust authentication and authorization mechanisms to be control access to sensitive data and functionality.
- Validating and sanitizing user input to prevent the injection attacks, like SQL injection and XSS (Cross-Site Scripting).
- Using a secure communication protocols like HTTPS to protect a data transmitted between client and the server.
- Regularly updating the dependencies and applying a security patches to avoid vulnerabilities.
30. Why are reliable styles essential and what apparatuses can be utilized to guarantee it?
Reliable style helps to colleagues alter extends effortlessly without getting used to the another style inevitably. Instruments that can help to incorporate Standard and ESLint.
31. What is the contrast between AngularJS and Node.js?
32. What is Mongoose?
Mongoose is the Object Document Mapper (ODM). This implies the Mongoose enables to characterize objects with the specific pattern that is mapped to a MongoDB archive.
33.What is Aggregation in MongoDB?
Aggregations operations process data records and return computed results. Aggregation operations group values from multiple documents together, and can perform a variety of operations on the grouped data to return a single result.
MongoDB provides three ways to perform aggregation:
- the aggregation pipeline,
- the map-reduce function,
- and single purpose aggregation methods and commands.
34.How do I perform the SQL JOIN equivalent in MongoDB?
Mongo is not a relational database, and the devs are being careful to recommend specific use cases for $lookup, but at least as of 3.2 doing join is now possible with MongoDB. The new $lookup operator added to the aggregation pipeline is essentially identical to a left outer join:
- from: <collection to join>,
- localField: <field from the input documents>,
- foreignField: <field from the documents of the “from” collection>,
- as: <output array field>
35.What is a blocking code?
If an application has to wait for some I/O operation in order to complete its execution any further then the code responsible for waiting is known as blocking code.
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36.How can you avoid callback hells?
To do so you have more options:
- modularization: break callbacks into independent functions
- use Promises
- use yield with Generators and/or Promises
37.What’s the event loop?
38.How does Node.js handle child threads?
If threading support is desired in a Node.js application, there are tools available to enable it, such as the ChildProcess module.
39.When should I use EventEmitter?
Whenever it makes sense for code to subscribe to something rather than get a callback from something. The typical use case would be that there’s multiple blocks of code in your application that may need to do something when an event happens.
40.How TypeScript is optionally statically typed language?
TypeScript is referred to as optionally statically typed, which means you can ask the compiler to ignore the type of a variable. Using any data type, we can assign any type of value to the variable. TypeScript will not give any error checking during compilation.
41.What is ClickJacking?
ClickJacking is an attack that fools users into thinking they are clicking on one thing when they are actually clicking on another. The attack is possible thanks to HTML frames (iframes).
Its other name, user interface (UI) redressing, better describes what is going on. Users think they are using a web page’s normal UI, but in fact there is a hidden UI in control; in other words, the UI has been redressed. When users click something they think is safe, the hidden UI performs a different action.
42.What is Cross-Site Request Forgery?
Cross-Site Request Forgery (CSRF) is an attack that forces authenticated users to submit a request to a Web application against which they are currently authenticated.
A CSRF attack tricks the victim into clicking a URL that contains a maliciously crafted, unauthorized request for a particular Web application. The user’s browser then sends this maliciously crafted request to a targeted Web application. The request also includes any credentials related to the particular website (e.g., user session cookies). If the user is in an active session with a targeted Web application, the application treats this new request as an authorized request submitted by the user.
43.Name the IDEs that are commonly used for Node.JS development?
The most popular IDE’s that can be used for Node.JS development include:
- Komodo IDE
- JetBrains IntelliJ IDEA
44.Define DATA modeling?
Data modeling is a term used in the context of Mongoose and MongoDB. As the name suggests, data modeling refers to the process of creating a data model for the data at hand so it can be stored in a database. A data model is a conceptual representation of data objects, the relation among different data objects, and the rules that define those relations.
45.Define a Test Pyramid. How can you actualize a Test Pyramid when discussing HTTP APIs?
Usually, full-stack web apps are large and complex. They are designed to expand their functionalities to serve hundreds of different requirements of millions of users. Consequently, as the size of a full-stack codebase and the number of users grow, the cost of dealing with bugs also escalates. This, however, can be successfully mitigated by applying the concept of the test pyramid to your codebase.
The test pyramid approach implies a radical way of thinking as to how different kinds of automated tests can and should be used to create a balanced portfolio. It emphasizes that the number of low-level UnitTests should be much more than high-level BroadStackTests running through a GUI.
When discussing HTTP APIs, you can actualize a test pyramid by following the steps mentioned below:
- Incorporate plenty of low-level unit tests for your model.
- Include fewer joining tests used for determining how your models collaborate with each other.
- Include fewer acknowledgment tests used for testing genuine HTTP endpoints.
46.Explain how does Node.js work?
A Node.js application creates a single thread on its invocation. Whenever Node.js receives a request, it first completes its processing before moving on to the next request.
Node.js works asynchronously by using the event loop and callback functions, to handle multiple requests coming in parallel. An Event Loop is a functionality which handles and processes all your external events and just converts them to a callback function. It invokes all the event handlers at a proper time. Thus, lots of work is done on the back-end, while processing a single request, so that the new incoming request doesn’t have to wait if the processing is not complete.
While processing a request, Node.js attaches a callback function to it and moves it to the back-end. Now, whenever its response is ready, an event is called which triggers the associated callback function to send this response.
47.Is Node.js entirely based on a single-thread?
Yes, it’s true that Node.js processes all requests on a single thread. But it’s just a part of the theory behind Node.js design. In fact, more than the single thread mechanism, it makes use of events and callbacks to handle a large no. of requests asynchronously.
To explain it practically, let’s assume there are 100s of requests lined up in Node.js queue. As per design, the main thread of Node.js event loop will receive all of them and forwards to background workers for execution. Once the workers finish processing requests, the registered callbacks get notified on event loop thread to pass the result back to the user.
48.What is Callback in Node.js?
We may call “callback” as an asynchronous equivalent for a function. Node.js makes heavy use of callbacks and triggers it at the completion of a given task. All the APIs of Node.js are written in such a way that they support callbacks.
For example, suppose we have a function to read a file, as soon as it starts reading the file, Node.js return the control immediately to the execution environment so that the next instruction can be executed. Once file read operation is complete, it will call the callback function and pass the contents of the file as its arguments. Hence, there is no blocking or wait, due to File I/O. This functionality makes Node.js as highly scalable, using it processes a high number of requests without waiting for any function to return the expected result.
49.What are Globals in Node.js?
- The Global keyword represents the global namespace object. It acts as a container for all other <global> objects. If we type <console.log(global)>, it’ll print out all of them.
- An important point to note about the global objects is that not all of them are in the global scope, some of them fall in the module scope. So, it’s wise to declare them without using the var keyword or add them to Global object.
- Variables declared using the var keyword become local to the module whereas those declared without it get subscribed to the global object.
50.How many types of Streams are present in Node.js?
Stream in Node.js are objects that allow reading data from a source or writing data to a specific destination in a continuous fashion. In Node.js, there are four types of streams.
- <Readable>: This is the Stream to be used for reading operation.
- <Writable>:It facilitates the write operation.
- <Duplex>: This Stream can be used for both the read and write operations.
- <Transform> :It is a form of a duplex Stream, which performs the computations based on the available input.
51.What DBMS technologies used for full stack development?
MySQL, Oracle, SQLServer, MongoDB are some of these technologies.
52.Explain software stack?
Software stack represents a group of programs used to bring about a particular result. It consists of an operating system with its applications.
53.Explain application server?
To create web applications as well as server environments for launching applications, application servers are used.
54.Explain referential transparency?
It is used in functional programming. For replacement of an expression, without changing the end outcome of the program, referential transparency is used.
55.Explain the debugging process of a complex program?
Before debugging, it is necessary to analyze the given problem. It is important to check the inputs and outputs. Input and output data sets are checked for potential input and outputs in the test data. Rectification involves avoiding the same error in the next phase and project.
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56.What are the steps in Continuous Integration?
Continuous integration works one step at a time.
- Maintain the notion for the code to be used in a project.
- Automate the build and it has to be self-testing.
- Everyone should integrate code every day on the build.
- As per production requirements build should be updated.
- Automate the deployment process.
57.How to Avoid Calling on Node.Js
Node.js uses a single threaded event indoors to activate the order processes. But if this approach is running longer than expected, it will prevent the whole process.
58.What is a bug – first request?
Error-to-use invitations are mainly used to add errors and data. By default, the first argument always refers to a bug, and the user must check if there is anything wrong with it.
59.The difference between functional and programmer errors in the context of Node.js.
Functional errors are not real bugs. They are computer errors, such as “request time” or “hardware error”. Programming errors are the actual errors in the index.
60.Explain the word I / O in the context of Node.js.
I / O has input and output. It is used to access anything outside the application. Once the I / O application is rejected it will be loaded into machine memory to enable programs.
62.What is the command used for node.js to export external libraries?
The command to import external libraries is “required”, for example, “var http = required (” http “).This will load the HTTP library and the single exported item through the http variable.
63.What does it mean to be “block-prevention” in node.js?
In “Node.js”, “Block-resistance” refers to blocking its IO. The moment uses “libuv” to handle its IO.
- Site-acoustic way In windows, it utilizes complete ports for Unic, which uses epoll or kqueue.
- Creates an unblock request and puts it within the so-called event ring on the request.
64.How does Node.js violate the issue of blocking I / O operations?
Node.js uses the event-based model at its center using an event loop to solve this problem: Texts.
65.Can you specify steps that can be single-tuned in Node.js?
You can async Node.js with the following steps:
- First Class Activities
- Operational system
- Event loops
66.What is Git?
A version control system, Git, allows developers to keep track of any changes made to the codebase. To get the latest out of it, it is vital to understand its important features properly.
67.What are different types of design patterns?
There are the following types:
- Creational patterns: They are used to create objects according to builder, singleton pattern, prototype, abstract factory, singleton pattern, etc.
- Structural patterns: They make the design easy by introducing a simple way for relationship realization among various entities like adapter, facade, bridge, decorator, proxy pattern, etc.
- Behavioral patterns: These are used to identify communication patterns among objects.
68.What is meant by application architecture?
Application Architecture deals with complex application development. It requires deep knowledge of structuring code, data needed in databases, separating files, computational tasks, hosting media files.
69.What is HTML DocType?
It is a command to the browser about the version markup language of page is written in. It is used before the HTML tag. Doctype refers to DTC i.e. document type definition.
70.How is the call different from applying?
Apply is used to call function as an array with arguments. Call uses explicit listing of parameters.
71.What is bootstrap in full-stack development?
Bootstrap represents an open-source kit with tools to develop HTML, JS and CSS content. With the help of SaaS variables, mixins, grids, prebuilt modules, and plugins, it can prototype an idea and build the app.
72.Why is REST important in the HTTP protocol?
REST is very simple and builds upon already existing systems. It uses existing HTTP features to achieve objectives. It eliminates the need to create new standards, technologies, frameworks, etc.
73.Explain CSS icons?
These are provided in vector libraries, scalable and customizable with CSS. Some libraries are bootstrap icons, font awesome and google icons.
It is known as Syntactically Awesome StyleSheet. It represents a CSS preprocessor and adds elegance to language. It permits the use of variables, mixins, nested rules, inline imports etc. With the help of Saas, huge stylesheets remain organized. You can run small stylesheets quickly with Sass.
Mixin represents a code block to group CSS declarations, to be reused on the site.
76.Explain anonymous functions?
These are functions without names. They are invoked automatically with a variable name.
77.What are the tasks to do with the use of the Event Ring?
- I / O Functions
- heavy calculation
78.Explain how “Control Flow” controls functional calls.
Control the execution order:
- Collect data
- integration limit
- Call the next step in the program
79.Why is Node.js single thread?
For the Async process, Node.js was created explicitly as a test. It is very much believed that Performance and scaling can be achieved through a single oscillation process typical web loads than regular thread-based implementation.
80.What is the control flow function?
Many asynchronous function is known as a common piece of code running between calls
81.Types of API functions in Node.js?
Node.js has two types of API functions
- Asynchronous, non-preventive operations
- synchronize and prevent operations
Multi-threading is used to improve CPU performance. It is based on execution of multiple threads and processes that the operating system supports.
83.Explain 3-tier model?
Three tier model consists of three layers for any application. Presentation layer which is associated with front end part and deals with user interface, business layer and is associated with back-end part, it deals with data validation. Third layer is the database layer and it deals with storage of data.
84.How is null different from undefined?
Null represents an object of no value. Whereas undefined represents a type.
86.What is an event cycle in Node.js?
Modify call events to activate and manipulate external events Used. So, in the I / O calls, node.js can switch from another request.
87.What is the difference between Node.js against Ajax?
Multi-threading is used to improve CPU performance. It is based on execution of multiple threads and processes that the operating system supports.
88.What is ‘Callback’ in Node.js?
The callback function is used in node.js to handle many of the server’s requests. If you have the server is going to take a long time to read a big file and if you do not want to get a server When dealing with other requests, read that big file and repeat the function. Call the backup function allows the server to cope with the pending request first and a function is called when it is present Concluded.
89. Explain the role of the request process in Node.js.
In Node.js, the request function is used to satisfy many requests from the server. If there is a large file that will take long for the server to perform, you can make a request to ensure that other requests to the server are uninterrupted.
90.Event-driven programming definition.
This program is a programming example that is characterized by events by news programs of other programs.
91.What is the biggest drawback of Node.js?
The biggest disadvantage is the fact that it is challenging to process a single thread to measure multiple core servers.
92. Explain REPL at Node.Js
REPL REAL REAL Print Loop It accepts, evaluates, and prints results. REPL provides the UNIX / Linux shell or a window console, which will include the command and the system, as a result we will respond to the output. REPL performs the following tasks.
93.What is the request on Node.Js?
We can call “callback” a coherent equivalent to a call. Node.js utilizes callbacks at large and stimulates the end of the given task. All APIs in Node.js are written to support callbacks.
94.What is a foot blade?
Initially, you can report a reputation after you know about it. Anger hell is a very hard tower, which is hard to read and maintain.
95.Explain LAMP stack?
LAMP stands for Linux, Apache, MySQL, PHP. It is used for web services. Its components support each other. Facebook is one of the web applications that runs on it.
96.What is MERN stack?
97.How will you define Continuous Integration?
It is the process of using codes built for testing. Developers should integrate a code daily during the phase of building. Every code is analysed automatically. Once this phase is over, code is deployed to team production and no human intervention is introduced. It is helpful in quick detection of problems.
98.What is semantic HTML?
HTML is used to define the loop of a webpage. Semantic HTML focuses on meaning or semantics of the information presented on the page. Search engines can find the significant text in the page and rank it accordingly..
99.Explain CSS Box model?
CSS Box model is used to decide the layout of content on the web page. Each element to be shown on the web page is represented as a rectangular box. Margin, edge, padding, and content edges are used with specific size and color, etc. for the content to be displayed on the screen.
100.How is REST different from SOAP?
These are two APIs with the following differences:
- REST is an architectural style with no official standard. SOAP is a protocol and with the official standard.
- REST makes use of numerous standards such as HTTP, JSON, URL, XML whereas SOAP uses mainly XML and HTTP.