MEAN Stack Interview Questions and Answers

Answer:

MEAN stack is an open-source technology, made up of four JavaScript-based technologies that help in the development of web apps and dynamic websites that are highly efficient and available.

MEAN is the abbreviation for

• MongoDB – The Database used to store data in document form
• ExpressJS – The middleware that facilitates and smoothens the back-end development
• AngularJS – An SPA (Single Page Application) power-packed frontend
• js – Single-Threaded Server-side scripting utilized to construct adaptable projects.

Answer:

The advantages of using the MEAN Stack are:

•  Isomorphic code: The use of JavaScript throughout the project makes the code isomorphic i.e. the backend and frontend both are implemented using the same tech and therefore become easy to go back and forth.
• Seamless-Communication: JSON is used both in AngularJS and Node JS. Even MongoDB is a component-based relational database that allows you to store documents in JSON format. This makes the communication between multiple components of the application seamless.
• Open Source: All the technologies used in MEAN Stack are open source and are available for free, therefore, reducing the development cost and helping cap the development approach using useful libraries and public repositories available online.
• Cloud Compatible: In case your project requires implementing cloud functionalities within the app, MongoDB is a good option to choose. Thus making MEAN a profitable share to have, at the same time reducing the cost of disk space.
• Fast And Reusable: The open and non-blocking architecture of Node.js makes it very fast. Another component of MEAN, Angular, is an open-source JavaScript framework that makes it easy to test, maintain, and reuse code.

Answer:

This should be answered in multiple points, keeping in mind the power of this technology stack becomes advantageous to web applications and their development.

• The purpose of using the MEAN stack is to create a full-stack web application that is fast, efficient, and easy to maintain.
• The MEAN stack is based on the JavaScript language, which makes it easy to develop and deploy web applications.
• The stack provides a complete development environment for web applications, assisting developers to create dynamic, data-driven web applications with minimal effort.
• Additionally, the MEAN stack enables developers to rapidly develop, test, and deploy full-stack web applications.

Answer:

In Node.js, the REPL (short for Read-Eval-Print-Loop) is a command-line interface that allows you to run JavaScript code directly from the terminal. It is useful for testing small snippets of code and exploring the language and its API.

Answer:

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

Answer:

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.

Answer:

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, and ordered fields, and to be efficient for encoding and decoding within different languages.

Answer:

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.

Answer:

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.

Answer:

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.

Answer:

Dependency Injection is a software design concept that allows you to use or inject a service in ways that are independent of any client consumption. By doing so, you essentially prevent the client from modifying dependencies when the underlying service changes.

The primary purpose of dependency injection is to separate the creation of clients’ dependencies from their behavior, thereby letting you design loosely coupled programs. In a loosely coupled program, the components usually consume functionality defined by interfaces without having any prior knowledge of which implementation classes are being used.

 Dependency injection allows you to modify or tweak the behavior of an application by altering the components that implement the interfaces defining an application’s features.

Answer:

Nose.js is essentially a single-thread process and does not involve child threads. Developers do not have to worry about thread management in Node.js. However, there are certain tasks like asynchronous I/O where the developers are exposed to child threads. Such threads do not executive JavaScript code applications. Also, the main loop doesn’t get blocked. This is why thread management is not an issue in Node.js. However, if developers need thread support, they can use the ChildProcess module.

Answer:

TypeScript is referred 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.

Answer:

• In Blue Green Deployment, you have TWO complete environments. One is 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.

Answer:

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:

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

Answer:

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

Answer:

The key difference between GraphQL and REST is that GraphQL does not have devoted resources, but everything is considered as a graph and therefore is linked and can be queried to an app’s exact needs.

Answer:

Angular applications comprise HTML templates along with the standard components. As the browser cannot understand these components and HTML templates directly, Angular apps must first be compiled before you can execute them in a browser. The Angular ahead-of-time (AOT) compiler changes the TypeScript code and Angular HTML into JavaScript code during the build phase before the browser downloads and executes the code. Compiling the Angular application in the build stage boosts a faster launch of Angular apps in the browser.

Following are the benefits of using AOT:

•  The browser can download a pre-compiled version of the application. The browser downloads executable code to render the Angular application immediately, without waiting for the app to compile first.
• The compiler inlines the CSS style sheets and external HTML templates within the application JavaScript with AOT, thus, removing separate AJAX requests for source files.
• The AOT compiler detects and reports any template binding errors during the build stage.
• Since AOT compiled HTML components and templates into JavaScript files before serving them as clients, there are no more templates left to read and no more risky client-side HTML/JavaScript evaluation requirements. This decreases the possibility of any injection attacks.

Answer:

In TypeScript, a Decorator indicates a special kind of declaration that is usually associated with a class declaration, accessor, method, property, or parameter. Decorators are functions that consider their target as an argument. They enable you to execute arbitrary code about the target execution or even swap the target with a new definition altogether.

Answer:

In MongoDB, indexes facilitate and support efficient query execution. Without indexes, MongoDB has to execute a collection scan wherein it needs to scan each document in a collection and choose the suitable documents matching the query statement. However, if an appropriate index has been assigned to each query, MongoDB can utilize the index to restrict the number of documents it has to evaluate.