Top Basic and Advanced Node js Interview Questions

Certified Security Modules can assess any third part codes that are catered into the software. A test pyramid is a metaphor that is used to make a bunch of software tests of different granularity. For example, unit testing, component testing, integration testing, system testing, end-to-end testing, UI testing. Despite having stable modules, Node.js still has immaturity within tools.

In JavaScript, the questions on back-end development equal the questions on Node.js, so there is no need to create a separate block of questions on the back-end. However, there is a need to see if the developer knows how to work with databases. Jason is a full-stack software engineer with experience building scalable web applications and features from scratch, using various stacks and frameworks. His focus is on the digital economy and SMB SaaS. He’s a strong communicator and has worked on large-scale project … The message queue is a queue that consists of asynchronous events (like callback functions of setTimeout, fetch responses, etc.) to be processed when the call stack is empty. It allows other code to be run in the meantime and prevents any blocking.

Thepackage.json file in Node.js is the heart of the entire application. It is basically the manifest file that contains the metadata of the project where we define the properties of a package. It is always advantageous to have a certification in the technology that you’re applying for.

How does the event loop work?

The asynchronicity in Node.js works due to its event-based, non-blocking I/O model. This list isn’t exhaustive, and interviewing typically includes an assessment of soft skills and technical ability through a take-home assignment or live coding exercise. You probably shouldn’t use a callback-based library in an application that uses Promises. Consistency is essential when developing applications as part of a bigger team. Experience with tools like EditorConfig, Prettier or ESLint ensures that the candidate knows about basic ways of keeping a code style and usage of certain patterns consistent. Using the async keyword in front of a function name wraps the return value of that function inside a Promise.

Thus, Node.js has a single-threaded model with event looping. Node.js interview questions are essential for preparing for a software developer interview. A lot of frameworks use blocking IO, they use pool of threads to perform concurrent operations. Each thread requires ≥ 1MB of memory, it means that number of threads are limited by server. If we are talking about some web-server application, blocking web-servers use at least 1 thread for each request.

David has been developing websites and web applications for all of his adult life. As a software engineer, he’s worked for many diverse software companies from early-stage startups to Google. David is experienced with many web frameworks and environments, but he particularly enjoys developing with Meteor.js. He appreciates the importance of quality code as well as the need to meet scheduling demands.

Node.js Developer interview questions

First of all, a developer can deal with nested callbacks by writing comments to explain complex lines of code. It not only helps the writer of the code to keep track of the series of callbacks, but it’s also so that someone else may be able to make sense of the code. One can also reduce code clutter by declaring functions beforehand, assigning names to functions for organization, using modules, using helpers from Async.js, etc.

Blocking is not a problem for short-running operations that can be run asynchronously, like handling HTTP requests. Process – It is one of the global objects but can turn asynchronous function into an async callback. It can be accessed from anywhere in the code, and it primarily gives back information about the application or the environment. Node.js is a single-threaded but highly scalable system that utilizes JavaScript as its scripting language.

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The Cluster module is one of the core Node.js modules and it allows running multiple Node.js worker processes that will share the same port. It is a pattern caused by intensively nested callbacks which are unreadable and unwieldy. It typically contains multiple nested callback functions which in turn make the code hard to read and debug. It is caused by improper implementation of the asynchronous logic. When running an application, callbacks are entities that have to be handled. In the case of Node.js, event loops are used for this purpose.

  • First of all, a developer can deal with nested callbacks by writing comments to explain complex lines of code.
  • So this mechanism saves execution time and increases performance of the application .
  • However, this architecture is easy to scale and fast to develop.
  • These asynchronous functions require a callback function to tackle errors and process the result.
  • This Edureka video on will introduce you to all the popular and trending technologies in the market which you should focus on in 2023.

The connect module in Node.js is used to provide communication between Node.js and the HTTP module. This also provides easy integration with Express.js, using the middleware modules. Coming to the fork() method, it can be considered as an instance of the already existing spawn() method. Spawning ensures that there is more than one active worker node to handle tasks at any given point in time.

Explain the concept of middleware in Node.js?

This gives the interviewer the impression that you have worked on the technology and that you are serious about using it for your career growth. More than this, it adds immense value to your resume and your knowledge on the topic at the same time. This line of questioning can be easily answered based on your previous experiences. Make sure to keep it concise and detailed as required when answering this question.

Node.js Developer interview questions

Server XSS (cross-site scripting) is a security threat when unreliable user input is included in an HTML response generated by the server. This input can be sent from a request or a stored location. The server-side code is vulnerable when a server XSS occurs, and the browser renders this response. To prevent server XSS, you should encode context-sensitive server-side output. Long polling is when the server holds a client’s connection open until new data is available. In the original client/server model, the web client is always the initiator of transactions — it’s the one to request data from the server.

What is the difference between Node.js and JavaScript?

Whether they are a beginner or a guru in Node.js programming, question them about work experience and past projects. These preparatory Node.js technical interview Middle+ Node.js Developer job questions enable you to determine who is the right fit for the job. An event loop in Node.js handles all the asynchronous callbacks in an application.

Whereas, the fork() in Node.js is a special instance of spawn() that executes a new instance of the V8 engine. This method simply means that multiple workers are running on a single Node code base for various task. Before I start off with this Node.js Interview Questions article, let me put forth a request to the readers who might have attended Node.js interviews in recent past. So, if you have come across such questions which were asked in interviews but are missing in this article, feel free to put those questions in the comment section below. We will try and answer those at the earliest so that others can also benefit from it. Here, the interviewer wants to know your understanding of the job role and the company architecture and your knowledge on the topic.

This completes our list of important Node.js interview questions for interview preparation. You must check out domain-specific preparation strategies and questions on the interview questions page. Internal exception handler run-time failure (code – 7) when there has been an exception when the bootstrapping function was called.

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Posted: Tue, 25 Oct 2022 07:00:00 GMT [source]

We created them to help you test your understanding of the popular programming language, or guide your initial technical screening with Node.js candidates. Glassdoor has 20 interview questions and reports from Node js developer interviews. Top 5 Node.js developer interview questions with detailed tips for both hiring managers and candidates.

I don’t give the exact definitions in google but I explained everything . Don’t know whether they know the definitions only or concepts . It’s also worth noting that using let instead of var in the for loop declaration can reduce the loop’s run time by over 50%. But such a change assumes you know the difference between let and var and whether this will have an effect on the behavior of your specific loop. In Node.js, however, declaring any variable outside of any function’s scope binds it only to the module’s own scope which therefore makes it much easier and faster to resolve. The time required to run this code in Google Chrome is considerably more than the time required to run it in Node.js.

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