MEAN Stack Interview Questions and Answers
- What’s the MEAN Stack?
The term MEAN stack refers to a series of technologies based on JavaScript for the development of Web applications. MEAN is an acronym for MongoDB, ExpressJS, AngularJS, and Node.js. MEAN is full-stack JavaScript, from client to server to database.
We can’t do much on the web without MEAN stack. It’s a full package. Furthermore, if we have a good understanding of JavaScript, we can develop an entire website easily and do not have to learn various languages to develop a website.
- Define Node.Js?
It’s a platform or runtime based on JavaScript that’s built on the V8 JavaScript engine of Chrome. It is a single-threaded program that uses competitiveness models based on the loop of events. It registers a callback that allows the applications to run, instead of blocking the execution. So as per it, Node.js can handle all these simultaneous operations without having to execute multiple threads which can be scaled quite well.
It uses C and C++, in addition to JavaScript. These are used for file system interaction. Instead, they continue using HTTP or TCP-based servers. It is now the most common platform for cross-platform or open platform applications, due to its rapidly growing popularity. You can use this to build fast and scalable network apps that can run smoothly on Linux, Microsoft Windows, or OSX.
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- When Node.js shouldn’t be used?
For spreading applications, node.js can be used. However, it’s one rib framework. Therefore, in cases where the system needs a long interval, we should not use it. If the server does some calculation, it will not be able to method the other requests at that time. Therefore, once there is a method that requires less dedicated C.P.U. time, Node.js is the best option.
If an application needs a long processing time, then node.js should be used. The explanation for this is, a single-threaded node is organized. Therefore, if a single application needs any long-running calculations in the background, it will not be able to process any further requests.
- What is DATA Modeling?
In the Mongoose and MongoDB context, data modeling determines what data can be in a database, and what data must be in a document. You might want to be able to save the first name, last name, email address, and telephone number while saving user information. But you only need an email address and a first name, and the email address must be unique. This information is defined as the basis for the data model in a schema.
- Why should we use Nodejs?
For what reason is Node.js so famous? Most of the web applications used a stateless request-and-response mechanism before the introduction of Node.js. To make the work of the developers rougher, they must always be sure that the correct code is written in the place when users work with the system so that the status of the web session is maintained.
But this issue has been resolved with the release of Node.js as users can now work in real-time and have 2-way communication with the server, i.e. anyone, whether the client or server, can start the communication.
- Explain callback in Node.js?
In node.js, the callback function is used to address multiple server requests. Like, if you have a large file that takes time for a server to read and do not want a server to read that big file, the callback is used when other requests are addressed. Call back allows the server to first handle the pending request and to call up a function after the request has been completed.
For example, if we have a file read function, Node.js automatically returns the control to the execution environment after it starts reading the file so that the next instruction can be executed. When the read operation of the file is complete, the callback function is called and the file’s content is passed as its argument. This feature makes Node.js highly scalable; with it, a large number of queries are processed without waiting for any feature to return the expected result.
- Explain the purpose of the ExpressJS package?
Express.js is a framework built on top of Node.js that makes it easier for server-side applications to manage data flow between server and routes. The lightweight and flexible framework offers a wide variety of functions necessary for the development of web and mobile applications. Express.js is developed on the Node.js middleware module called connect. The connection module also uses HTTP to communicate with Node.js. It makes it easy to integrate with Express.js if you work with any connect-based middleware modules.
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- Explain the usage of a buffer class in Node.js?
In Node.js the buffer class is used to store raw data as a whole array. But it is similar to a primitive memory assignment outside the V8 heap. It is a global class that can be easily accessed without importing a buffer module in an application. Buffer classes are used because pure JavaScript is not binary data compatible. Therefore, it’s necessary to handle octet streams when dealing with TCP streams or the file system.
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- Why we use mean stack?
Web applications with Node.js can easily be created, as they offer a good number of JavaScript modules from their humongous library. Mean stack allows developers only to write JavaScript code in one language, which is a simple and quick language on both the client and the server pages.
- Define Event Emitter of Node.js
You can build and manage customized events with the event module present at Node. Js. In this context, it should be noted that the event module contains the game emitter class, which can be used for handling and raising personalized events. Furthermore, you should be aware that when an event emitter detects an error, it will emit an error case. On the other side, it sends a sample with the name of the new user if a new user is added. Also, it sends a demonstration by remote user’s name when the current user is disabled.
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