MEAN STACK Interview Questions [WITH EXAMPLE ANSWERS]
MEAN STACK Interview Questions and Answers

MEAN STACK Interview Questions [WITH EXAMPLE ANSWERS]

Last updated on 05th Jun 2020, Blog, Interview Questions

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MEAN STACK is a free and open-source JavaScript software stack for building dynamic web sites and web applications. Because all components of the MEAN stack support programs that are written in JavaScript, MEAN applications can be written in one language for both server-side and client-side execution environments.The development time can be reduced, leading to a lower development cost. Fast MVP development and scalability.

1.What is the Mean Stack?

Ans:

Mean stack is a combination of four popular JavaScript-based technologies MongoDB, Express, AngularJS and Node that allows developers to develop complete web applications.

2.What is Express?

Ans:

 Express is a lightweight web framework for Node.js.It provides robust and scalable solutions to build single and multi-page web applications. Express is inspired by Sinatra (Ruby framework).

3.Explain Mongoose?

Ans:

Mongoose is a MongoDB Object Data Modeling (ODM) library for MongoDB and NodeJS.It provides a straight-forward, schema-based solution to model your application data. It includes built-in typecasting, validation, query building, business logic hooks and more, out of the box.

4.How AngularJS is different from NodeJS?

Ans:

The purpose of Angular and Node Js is totally Different.

AngularJS is a front-end framework that deals with the UI and client side of an application while NodeJs is a runtime environment useful in building server-side applications.

5.How to install express?

Ans:

Run below command to install express:

  • npm install express –save

6.Explain Routing in Express.js?

Ans:

 Routing is a mechanism used by frameworks to decide how a URL/endpoint is responded/handled by the server. Express provides an excellent way to handle applications routing. Below is basic code to handle routing in Express.

  • var express = require(‘express’)
  • var app = express()
  • // respond with “hello world” when a GET request is made to the homepage
  • app.get(‘/’, function (req, res) {
  •   res.send(‘hello world’)
  • });

7.What are the features of Node.js?

Ans:

Node.js is a single-threaded but highly scalable system that utilizes JavaScript as its scripting language. It uses asynchronous, event-driven I/O instead of separate processes or threads. It is able to achieve high output via single-threaded event loop and non-blocking I/O.

8.What is Routing Guard in Angular?

Ans:

Angular’s route guards are interfaces which can tell the router whether or not it should allow navigation to a requested route. They make this decision by looking for a true or false return value from a class which implements the given guard interface.

9.What is Scope in JavaScript?

Ans:

 In JavaScript, each function gets its own scope. Scope is basically a collection of variables as well as the rules for how those variables are accessed by name. Only code inside that function can access that function’s scoped variables.

A variable name has to be unique within the same scope. A scope can be nested inside another scope. If one scope is nested inside another, code inside the innermost scope can access variables from either scope.

10.What is a service, and when will you use it?

Ans:

Angular services are singleton objects which get instantiated only once during the lifetime of an application. They contain methods that maintain data throughout the life of an application, i.e. data does not get refreshed and is available all the time. The main objective of a service is to organize and share business logic, models, or data and functions with different components of an Angular application.

The separation of concerns is the main reason why Angular services came into existence. An Angular service is a stateless object and provides some very useful functions.

11.What is the difference between Linear Search and Binary Search?

Ans:

  • A linear search looks down a list, one item at a time, without jumping. In complexity terms this is an O(n) search – the time taken to search the list gets bigger at the same rate as the list does.
  • A binary search is when you start with the middle of a sorted list, and see whether that’s greater than or less than the value you’re looking for, which determines whether the value is in the first or second half of the list. Jump to the half way through the sublist, and compare again etc. In complexity terms this is an O(log n) search – the number of search operations grows more slowly than the list does, because you’re halving the “search space” with each operation.

12.What is Dependency Injection?

Ans:

Dependency injection makes it easy to create loosely coupled components, which typically means that components consume functionality defined by interfaces without having any first-hand knowledge of which implementation classes are being used.

13.What is Inversion of Control?

Ans:

  Inversion of control is a broad term but for a software developer it’s most commonly described as a pattern used for decoupling components and layers in the system.

14.What does Containerization mean?

Ans:

Containerisation is a type of virtualization strategy that emerged as an alternative to traditional hypervisor-based virtualization.

In containerization, the operating system is shared by the different containers rather than cloned for each virtual machine. For example Docker provides a container virtualization platform that serves as a good alternative to hypervisor-based arrangements.

15.How does the Centralized Workflow work?

Ans:

The Centralized Workflow uses a central repository to serve as the single point-of-entry for all changes to the project. The default development branch is called master and all changes are committed into this branch.

16.Compare SQL databases and MongoDB at a high level.

Ans:

 SQL databases store data in the form of tables, rows, columns and records. This data is stored in a pre-defined data model which is not very much flexible for today’s real-world highly growing applications. MongoDB in contrast uses a flexible structure which can be easily modified and extended.

17.What is BSON in MongoDB?

Ans:

 BSON is a binary serialization format used to store documents and make remote procedure calls in MongoDB. BSON extends the JSON model to provide additional data types, ordered fields, and to be efficient for encoding and decoding within different languages.

18.What are Indexes in MongoDB?

Ans:

 Indexes support the efficient execution of queries in MongoDB. Without indexes, MongoDB must perform a collection scan, i.e. scan every document in a collection, to select those documents that match the query statement. If an appropriate index exists for a query, MongoDB can use the index to limit the number of documents it must inspect.

19.What is the difference between Classes and Interfaces in Typescript?

Ans:

We use classes as object factories. A class defines a blueprint of what an object should look like and act like and then implements that blueprint by initialising class properties and defining methods. Classes are present throughout all the phases of our code.

Unlike classes, an interface is a virtual structure that only exists within the context of TypeScript. The TypeScript compiler uses interfaces solely for type-checking purposes. Once code is transpiled to its target language, it will be stripped from interfaces.

A class may define a factory or a singleton by providing initialisation to its properties and implementation to its methods, an interface is simply a structural contract that defines what the properties of an object should have as a name and as a type.

20.What is “Decorators” in TypeScript?

Ans:

A Decorator is a special kind of declaration that can be attached to a class declaration, method, accessor, property, or parameter. Decorators are functions that take their target as the argument. With decorators we can run arbitrary code around the target execution or even entirely replace the target with a new definition.

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    21.What is CORS and how to enable one?

    Ans:

    A request for a resource (like an image or a font) outside of the origin is known as a cross-origin request. CORS (cross-origin resource sharing) manages cross-origin requests. CORS allows servers to specify who (i.e., which origins) can access the assets on the server, among many other things.

    Access-Control-Allow-Origin is an HTTP header that defines which foreign origins are allowed to access the content of pages on your domain via scripts using methods such as XMLHttpRequest.

    For example, if your server provides both a website and an API intended for XMLHttpRequest access on a remote website, only the API resources should return the Access-Control-Allow-Origin header. Failure to do so will allow foreign origins to read the contents of any page on your origin.

    22.What is Cross Site Scripting (XSS)?

    Ans:

    By using Cross Site Scripting (XSS) technique, users execute malicious scripts (also called payloads) unintentionally by clicking on untrusted links and hence, these scripts pass cookies information to attackers.

    23.How to bundle an Angular app for production?

    Ans:

    OneTime Setup:

    • npm install -g @angular/cli
    • ng new projectFolder creates a new application

    Bundling Step:

    • ng build –prod (run in command line when directory is projectFolder)
    • flag prod _bundle for production

    bundles are generated by default to projectFolder/dist/

    24.What’s new in Angular 6 and why shall we upgrade to it?

    Ans:

    Angular Elements : Angular Elements is a project that lets you wrap your Angular components as Web Components and embed them in a non-Angular application.

    • New Rendering Engine: Ivy – increases in speed and decreases in application size.
    • Tree-shakeable providers : a new, recommended, way to register a provider, directly inside the @Injectable() decorator, using the new providedIn attribute
    • RxJS 6: Angular 6 now uses RxJS 6 internally, and requires you to update your application also. RxJS released a library called rxjs-compat, that allows you to bump RxJS to version 6.0 even if you, or one of the libraries you’re using, is still using one of the “old” syntaxes.

    25.What is AOT?

    Ans:

    The Angular Ahead-of-Time compiler precompiled application components and their templates during the build process. Apps compiled with AOT launch faster for several reasons.

    • Application components execute immediately, without client-side compilation.
    • Templates are embedded as code within their components so there is no client-side request for template files.
    • You don’t download the Angular compiler, which is pretty big on its own.
    • The compiler discards unused Angular directives that a tree-shaking tool can then exclude.

    26.What is Redux and how does it relate to an Angular app?

    Ans:

    Redux is a way to manage application state and improve maintainability of asynchronicity in your application by providing a single source of truth for the application state, and a unidirectional flow of data change in the application. ngrx/store is one implementation of Redux principles.

    27.What is a Grid System in CSS?

    Ans:

     A grid system is a structure that allows for content to be stacked both vertically and horizontally in a consistent and easily manageable fashion. Grid systems include two key components: rows and columns.

    Some Grid Systems:

    • Simple Grid
    • Pure
    • Flexbox Grid
    • Bootstrap
    • Foundation

    28.How is responsive design different from adaptive design?

    Ans:

     Both responsive and adaptive design attempt to optimize the user experience across different devices, adjusting for different viewport sizes, resolutions, usage contexts, control mechanisms, and so on.

    Responsive design works on the principle of flexibility — a single fluid website that can look good on any device. Responsive websites use media queries, flexible grids, and responsive images to create a user experience that flexes and changes based on a multitude of factors. Like a single ball growing or shrinking to fit through several different hoops.

    Adaptive design is more like the modern definition of progressive enhancement. Instead of one flexible design, adaptive design detects the device and other features, and then provides the appropriate feature and layout based on a predefined set of viewport sizes and other characteristics. The site detects the type of device used, and delivers the pre-set layout for that device. Instead of a single ball going through several different-sized hoops, you’d have several different balls to use depending on the hoop size.

    29.What’s the difference between a blue/green deployment and a rolling deployment?

    Ans:

    • In Blue Green Deployment, you have TWO complete environments. One is the Blue environment which is running and the Green environment to which you want to upgrade. Once you swap the environment from blue to green, the traffic is directed to your new green environment. You can delete or save your old blue environment for backup until the green environment is stable.
    • In Rolling Deployment, you have only ONE complete environment. The code is deployed in the subset of instances of the same environment and moves to another subset after completion.

    30.Explain the main difference between REST and GraphQL

    Ans:

     The main and most important difference between REST and GraphQL is that GraphQL is not dealing with dedicated resources, instead everything is regarded as a graph and therefore is connected and can be queried to app exact needs.

    31.Could you explain the difference between ES5 and ES6

    Ans:

    • ECMAScript 5 (ES5): The 5th edition of ECMAScript, standardized in 2009. This standard has been implemented fairly completely in all modern browsers
    • ECMAScript 6 (ES6)/ ECMAScript 2015 (ES2015): The 6th edition of ECMAScript, standardized in 2015. This standard has been partially implemented in most modern browsers.

    32.What does MongoDB not being ACID compliant really mean?

    Ans:

     It’s actually not correct that MongoDB is not ACID-compliant. On the contrary, MongoDB is ACID-compliant at the document level.

    Any update to a single document is:

    • Atomic: it either fully completed or it does not
    • Consistent: no reader will see a “partially applied” update
    • Isolated: again, no reader will see a “dirty” read
    • Durable: (with the appropriate write concern)

    What MongoDB doesn’t have is transactions – that is, multiple-document updates that can be rolled back and are ACID-compliant.

    33.What is Aggregation in MongoDB?

    Ans:

     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?

    Ans:

    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:

    • {
    •    $lookup:
    •      {
    •        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?

    Ans:

    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?

    Ans:

    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?

    Ans:

    The event loop is what allows Node.js to perform non-blocking I/O operations — despite the fact that JavaScript is single-threaded — by offloading operations to the system kernel whenever possible.

    38.How does Node.js handle child threads?

    Ans:

     Node.js, in its essence, is a single thread process. It does not expose child threads and thread management methods to the developer. Technically, Node.js does spawn child threads for certain tasks such as asynchronous I/O, but these run behind the scenes and do not execute any application JavaScript code, nor block the main event loop.

    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?

    Ans:

     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?

    Ans:

    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?

    Ans:

     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?

    Ans:

    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?

    Ans:

    The most popular IDE’s that can be used for Node.JS development include:

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

    44.Define DATA modeling?

    Ans:

     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?

    Ans:

    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?

    Ans:

     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?

    Ans:

    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.

    Moreover, Node.js has an optimized design which utilizes both JavaScript and C++ to guarantee maximum performance. JavaScript executes at the server-side by Google Chrome v8 engine. And the C++ libUV library takes care of the non-sequential I/O via background workers.

    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?

    Ans:

     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?

    Ans:

    • 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?

    Ans:

     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?

    Ans:

     MySQL, Oracle, SQLServer, MongoDB are some of these technologies.

    52.Explain software stack?

    Ans:

    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?

    Ans:

     To create web applications as well as server environments for launching applications, application servers are used.

    54.Explain referential transparency?

    Ans:

     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?

    Ans:

    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?

    Ans:

    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

    Ans:

    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?

    Ans:

    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.

    Ans:

    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.

    Ans:

    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.

    61.What is the relationship of Node.js with JavaScript?

    Ans:

     Node.js is not a javascript framework, and many of its modules are written here.

    • It allows developers to create new modules for JavaScript.
    • Node.js is a virtual machine, which makes JavaScript to get a high output as a scripting language.

    62.What is the command used for node.js to export external libraries?

    Ans:

    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?

    Ans:

    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.
    • JavaScript ‘request’ in the main javascript thread.

    64.How does Node.js violate the issue of blocking I / O operations?

    Ans:

    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?

    Ans:

     You can async Node.js with the following steps:

    • First Class Activities
    • Operational system
    •  counters
    •  Event loops

    66.What is Git?

    Ans:

    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?

    Ans:

    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?

    Ans:

    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?

    Ans:

    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?

    Ans:

     Apply is used to call function as an array with arguments. Call uses explicit listing of parameters.

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    71.What is bootstrap in full-stack development?

    Ans:

     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?

    Ans:

    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?

    Ans:

    These are provided in vector libraries, scalable and customizable with CSS. Some libraries are bootstrap icons, font awesome and google icons.

    74.Explain Sass?

    Ans:

     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.

    75.Explain Mixin?

    Ans:

    Mixin represents a code block to group CSS declarations, to be reused on the site.

    76.Explain anonymous functions?

    Ans:

    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?

    Ans:

    •  I / O Functions
    • heavy calculation

    78.Explain how “Control Flow” controls functional calls.

    Ans:

    Control the execution order:

    • Collect data
    • integration limit
    • Call the next step in the program

    79.Why is Node.js single thread?

    Ans:

     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?

    Ans:

     Many asynchronous function is known as a common piece of code running between calls

    81.Types of API functions in Node.js?

    Ans:

    Node.js has two types of API functions

    • Asynchronous, non-preventive operations
    • synchronize and prevent operations

    82.Explain multi-threading?

    Ans:

    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?

    Ans:

    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?

    Ans:

    Null represents an object of no value. Whereas undefined represents a type.

    85.Why do node.js quickly draw from JavaScript programmers?

    Ans:

    Node.js draws attention because this is a loop-based server for JavaScript. Node.js gives user, the ability to write javascript on the server, accessing the HTTP stack, file I / O, TCP etc. and databases.

    86.What is an event cycle in Node.js?

    Ans:

    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?

    Ans:

    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?

    Ans:

    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.

    Ans:

    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.

    Ans:

    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?

    Ans:

    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

    Ans:

    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?

    Ans:

     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?

    Ans:

    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?

    Ans:

     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?

    Ans:

     MERN stands for MongoDB, Express, React, Node.js. It is a group of JavaScript technologies. It is used for web application development a lot nowadays.

    97.How will you define Continuous Integration?

    Ans:

     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?

    Ans:

     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?

    Ans:

     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?

    Ans:

    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.

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