Top 50 Mean stack interview questions 2018

Top 50 Mean stack interview questions 2018

1.What’s the MEAN Stack?
The term MEAN stack refers to a collection of JavaScript based technologies used to develop web applications. MEAN is an acronym for MongoDB, ExpressJS, AngularJS and Node.js. From client to server to database, MEAN is full stack JavaScript.

2.What is Express?
Express is one the most prevalent and generally utilized web systems in Node.js advancement zone. Express is a negligible web server based on Node.js that gives all the basic usefulness required for conveying web applications to the program and cell phones. ExpressJS enables you to deal with Routes, Server, and I/O stuff effortlessly.

3.What is Node.js?
Node.js is a headless JavaScript runtime. It is literally the same JavaScript engine (named V8) that runs inside of Google Chrome, except that with Node.js, you can run JavaScript from the command line instead of in your browser.

4.What is DATA Modeling?
Data modeling, in the context of Mongoose and MongoDB, is defining what data can be in a document, and what data must be in a document. When storing user information you might
want to be able to save first name, last name, email address and phone number. But you only need first name and email address, and the email address must be unique. This information is defined in a schema, which is used as the basis for the data model.

5. Servers dedicated for advertisement.
Again, we have got servers that are dedicated to handle thousands of requests which can be used for downloading the advertisements from the central host and the perfect answers for handling these tasks are Node.JS.

6. Servers dedicated for streaming.
Another ideal situation to use Node.js is for the multimedia system streaming servers wherever shopper fireplace request’s towards the server which is used to transfer totally different multimedia system contents from it.
Summarizing the whole, using Node.js is a smart choice, after you want high levels of concurrency, however, less quantity of dedicated C.P.U. Time.
Last however not the smallest amount, since Node.js uses JavaScript internally, therefore it fits best for building client-side applications that additionally use JavaScript.

7. When Node.js shouldn’t be used?
Node.js can be used for the spread of applications. However, it’s one rib framework. Therefore we shouldn’t be using it for cases wherever the appliance needs a long interval. In case the server is performing some calculation, at that time it won’t be allow to method the other requests. So, Node.js is the best option once when there is a process that wants less dedicated C.P.U. Time.

8. What are the IDEs which can be used for Node.JS development?
The most common types of IDE’s that can be used for Node.JS development applications are:

1. Cloud9
2. JetBrainsWebStorm
3. JetBrainsInteliJ IDEA
4. Komodo IDE
5. Eclipse
6. Atom

These are the best IDE’s which you can use for developing Node.JS programs. Each of them is top choices of IDEs which can be used for developing Node.js.

9.What Is The Difference Between Nodejs, AJAX, And JQuery?

The one common trait between Node.js, AJAX, and jQuery is that all of them are the advanced implementation of JavaScript. However, they serve completely different purposes.

Node.Js – It is a server-side platform for developing client-server applications. For example, if we’ve to build an online employee management system, then we won’t do it using client-side JS. But the Node.js can certainly do it as it runs on a server similar to Apache, Django not in a browser.

AJAX (Aka Asynchronous Javascript And XML) – It is a client-side scripting technique, primarily designed for rendering the contents of a page without refreshing it. There are a no. of large companies utilizing AJAX such as Facebook and Stack Overflow to display dynamic content.

JQuery –It is a famous JavaScript module which complements AJAX, DOM traversal, looping and so on. This library provides many useful functions to help in JavaScript development. However, it’s not mandatory to use it but as it also manages cross-browser compatibility, so can help you produce highly maintainable web applications.

10.What’s the difference between operational and programmer errors?
Operation errors are not bugs, but problems with the system, like request timeout or hardware failure.
On the other hand programmer errors are actual bugs.

11.What’s a test pyramid? How might you actualize it when discussing HTTP APIs?
A test pyramid portrays that when works test cases there ought to be significantly more low-level unit tests than abnormal state end-to-end tests.

12.When discussing HTTP APIs, it might come down to this:
A great deal of low-level unit tests for your models
Less joining tests, where your test how your models collaborate with each other
Significantly less acknowledgment tests, where you test the genuine HTTP endpoints

13.Explain callback in Node.js?
A callback work is called toward the culmination of a given errand. This enables other code to be keep running meanwhile and keeps any blocking. Being an offbeat stage, Node.js intensely depends on callback. All APIs of Node are composed to help callbacks.

14. Define Event Emitter of Node.js
The event module present in the Node.Js would allow you to create and manage custom events. In this context, it is important to note that the event module comprises of the class of game emitter that can be used to handle and raise custom events. You should also be aware of the fact that when an event emitter comes across an error, it usually emits an error event. On the other hand, when a new user gets added, it sends out a demonstration by the name of a new user. Moreover, when the new user gets removed, it sends a demonstration by the name of remote user.

15. What do you mean by NPM of Node.js?
The full form of NPM is Node Package Manager. It is associated with the two main functionalities which are listed below:

It usually works as a command line utility to install the packages. It also carries out version management and dependency management of various Node.Js packages.
It also works as an online repository in the case of Node.Js packages. These are also present in the .org file of Node.Js.

Apart from the questions mentioned above, always take into account the multi-core platforms of the Node.Js architecture. You also have to take into account the callback handler so that you can excel in the interview session.

17. What does it signify “non-obstructing” in node.js?
In node.js “non-blocking” implies that its IO is non-blocking. Hub utilizes “libuv” to deal with its IO in a stage rationalist manner. On windows, it utilizes finish ports for UNIX it utilizes epoll or kqueue and so on. Along these lines, it makes a non-blocking demand and upon a demand, it lines it inside the occasion circle which call the JavaScript ‘callback’ on the fundamental JavaScript string.

18. What is the type of request that is utilized as a part of node.js to import outside libraries?
Summon “require” is utilized for bringing in outer libraries, for instance, “var http=require (“http”)”. This will stack the http library and the single sent out protest through the http variable.

19. Say the structure most regularly utilized as a part of node.js
“Express” is the most well-known structure utilized as a part of node.js

20. What are the upsides and downsides of Node.js?
Advantages:
a) If your application does not have any CPU concentrated calculation, you can construct it in JavaScript through and through, even down to the database level in the event that you utilize JSON stockpiling object DB like MongoDB.
b) Crawlers get a full-rendered HTML reaction, which is significantly more SEO well disposed instead of a solitary page application or a web sockets application keep running over Node.js.

Disadvantages:
a) Any concentrated CPU calculation will square node.js responsiveness, so a strung stage is a superior approach.
b) Using social database with Node.js is viewed as less good

21. What is an occasion circle in Node.js?
To process and handle outside occasions and to change over them into callback summons an occasion circle is utilized. Along these lines, at I/O calls, node.js can change starting with one demand then onto the next.

22. What is the upside of utilizing node.js?
a) It gives a simple method to construct adaptable system programs
b) Generally quick
c) Great simultaneousness
d) Asynchronous everything
e) Almost never pieces

23. What are the two sorts of API works in Node.js?
The two kinds of API works in Node.js are
a) Asynchronous, non-blocking capacities
b) Synchronous, blocking capacities

24. What are the Challenges with Node.js?
Accentuating on the specialized side, it’s a touch of test in Node.js to have one process with one string to scale up on multi centre server.

25. What does it signify “non-hindering” in node.js?
In node.js “non-blocking” implies that its IO is non-blocking. Hub utilizes “libuv” to deal with its IO in a stage sceptic way. On windows, it utilizes fulfilment ports for UNIX it utilizes epoll or kqueue and so forth. In this way, it makes a non-blocking demand and upon a demand, it lines it inside the occasion circle which calls the JavaScript ‘callback’ on the fundamental JavaScript string.

26. What is node.js?
Node.js is a Server side scripting which is utilized to construct adaptable projects. Its various favorable circumstances over other server side are dialects, the noticeable being non-blocking I/O.

27.How node.js functions?
Node.js takes a shot at a v8 situation, it is a virtual machine that uses JavaScript as its scripting dialect and accomplishes high yield by means of non-blocking I/O and single strung occasion circle.

28. What do you mean by the term I/O?
I/O is the shorthand for information and yield, and it will get to anything outside of your application. It will be stacked into the machine memory to run the program, once the application is begun.

29. What does occasion driven programming mean?
In PC programming, occasion driven writing computer programs is a programming worldview in which the stream of the program is controlled by occasions like messages from different projects or strings. It is an application engineering system partitioned into two areas 1) Event Selection 2) Event Handling

30. Where would we be able to utilize node.js?
Node.js can be utilized for the accompanying purposes
a) Web applications (particularly constant web applications)
b) Network applications
c) Distributed frameworks
d) General reason applications

31. What’s a test pyramid? By what method may you complete it while talking about HTTP APIs?
A test pyramid depicts that when works test cases there should be essentially more low-level unit tests than strange state end-to-end tests.

While talking about HTTP APIs, it may come down to this:

1. A lot of low-level unit tests for your models
2. Less joining tests, where your test how your models team up with each other
3. Essentially less affirmation tests, where you test the certifiable HTTP endpoints

32. Why are reliable styles essential and what apparatuses can be utilized to guarantee it?
Reliable style helps colleagues alter extends effortlessly without getting used to another style inevitably. Instruments that can help incorporate Standard and ESLint.

33.What is the contrast amongst AngularJS and Node.js?
Angular.JS is a web application improvement structure while Node.js is a runtime framework.

34. What Is Mongoose?
Mongoose is an Object Document Mapper (ODM). This implies Mongoose enables you to characterize objects with a specifically pattern that is mapped to a MongoDB archive.

35. What’s the MEAN Stack?
The notion of MEAN stack alludes to the collection of advancements that are JavaScript based. These are also used to create web applications. MEAN is the abbreviation for ExpressJS, AngularJS MongoDB and Node.js. From customer to server to database, MEAN is full stack JavaScript.

36. What is express?
Express is one the most pervasive and by and large used web frameworks in Node.js headway zone. Express is an insignificant web server in view of Node.js that gives all the essential value required for passing on web applications to the program and PDAs. ExpressJS empowers you to manage Routes, Server, and I/O stuff easily.

37.Can you access DOM in node?
No, you cannot access DOM in node.

38. Using the event loop what are the tasks that should be done asynchronously?
a) I/O operations

b) Heavy computation

c) Anything requiring blocking

39. Why node.js is quickly gaining attention from JAVA programmers?
Node.js is quickly gaining attention as it is a loop based server for JavaScript. Node.js gives user the ability to write the JavaScript on the server, which has access to things like HTTP stack, file I/O, TCP and databases.

40. What are the two arguments that async.queue takes?
The two arguments that async.queue takes
a) Task function
b) Concurrency value

41. What is an event loop in Node.js ?
To process and handle external events and to convert them into callback invocations an event loop is used. So, at I/O calls, node.js can switch from one request to another .

42. Mention the steps by which you can async in Node.js?
By following steps you can async Node.js
a) First class functions
b) Function composition
c) Callback Counters
d) Event loops

43. What are the pros and cons of Node.js?
Pros:
a) If your application does not have any CPU intensive computation, you can build it in Javascript top to bottom, even down to the database level if you use JSON storage object DB like MongoDB.
b) Crawlers receive a full-rendered HTML response, which is far more SEO friendly rather than a single page application or a websockets app run on top of Node.js.
Cons:
a) Any intensive CPU computation will block node.js responsiveness, so a threaded platform is a better approach.
b) Using relational database with Node.js is considered less favourable

44. How Node.js overcomes the problem of blocking of I/O operations?
Node.js solves this problem by putting the event based model at its core, using an event loop instead of threads.

45. What is the difference between Node.js vs Ajax?
The difference between Node.js and Ajax is that, Ajax (short for Asynchronous Javascript and XML) is a client side technology, often used for updating the contents of the page without refreshing it. While,Node.js is Server Side Javascript, used for developing server software. Node.js does not execute in the browser but by the server.

46. What is the difference between Node.js vs Ajax?
The difference between Node.js and Ajax is that, Ajax (short for Asynchronous Javascript and XML) is a client side technology, often used for updating the contents of the page without refreshing it. While,Node.js is Server Side Javascript, used for developing server software. Node.js does not execute in the browser but by the server.

47. What are the Challenges with Node.js ?
Emphasizing on the technical side, it’s a bit of challenge in Node.js to have one process with one thread to scale up on multi core server.

48. What does it mean “non-blocking” in node.js?
In node.js “non-blocking” means that its IO is non-blocking. Node uses “libuv” to handle its IO in a platform-agnostic way. On windows, it uses completion ports for unix it uses epoll or kqueue etc. So, it makes a non-blocking request and upon a request, it queues it within the event loop which call the JavaScript ‘callback’ on the main JavaScript thread.

49. What is the command that is used in node.js to import external libraries?
Command “require” is used for importing external libraries, for example, “var http=require (“http”)”. This will load the http library and the single exported object through the http variable.

50. Mention the framework most commonly used in node.js?
“Express” is the most common framework used in node.js

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