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Node.js Interview Questions to Ask a Candidate


Hiring is tough, especially when it comes to candidates with specific proficiencies. Node.js developers are in demand today since the popularity of Node.js keeps growing. According to a global survey, the use of Node.js worldwide is expected to be increasing by 76% annually. Despite computer programming being quite a mature industry with a multi-decade history, a lot of developers are still honing their skills on their own. About 38% of Node.js developers have informal education based on online courses, while 72% of them get their knowledge from StackOverflow.

NodeJS stats


A software company may face a challenge when trying to select a suitable employee from a list of potential candidates. Hence, a list of basic Node.js interview questions is worth always having at hand. Read also our guide on how to hire a rockstar drupal developer. We collected a dozen questions that might help HR specialists conduct better job interviews with Node.js developers. Since the format of the present post is far from a detailed listing of all possible aspects of Node.js divided into different levels of training (senior, middle, junior), we focus on the most essential questions that can reveal the overall educational level of the promising prospects.

  1. What does Node.js have to do with JavaScript? The question might seem too primitive for experienced developers, but it covers many programming fundamentals such as the difference between a programming language and a scripting language along with the scope of applications appropriate for Node.js. Ask your candidate to address the issue as extensively as possible.

  2. Why, in your opinion, was the V8 engine necessary? This question tackles a range of topics: whether Node.js is really single-threaded, how JavaScript is converted into a low-level language, and what performance consequences result from it regarding the applications created with Node.js. A detailed response to this question may also cover some other relevant features of V8 such as the memory structure, functions of Garbage collector, and memory leaks along with methods of addressing them. The discussed basics of V8 can logically lead to the next question: 

  3. How does the Event loop work? Our developers believe this is the most important among the Node.js interview questions. A candidate who really knows their job can explain, for example, how to block the Event loop and what the difference between setImmediate and setTimeout is. This is about how the callback function is executed and why it is looped. A candidate who reveals true expertise in this issue is most probably a well-prepared Node.js developer. Hence, it is possible to skip other purely technical details and move to organizational and personal questions. But if a candidate is not confident enough, the following question should be asked:

  4. What lies behind the single-threaded nature of Node.js? The question aims at making the candidate reflect upon the importance of the fact that Node.js is single-threaded to describe its pros and cons. A candidate should explain that Node.js is appropriate for those developers who face numerous I/O and asynchronous events. Thus, it can hardly fit heavy synchronous computations like in machine learning and the IoT. Finally, the question can be logically extended by the explanation of which applications are appropriate for Node.js and which ones are not.

  5. What disadvantages do you see in using Node.js? The question indirectly touches on some other technologies such as C# and Java, for example. Besides, it covers some obsolete types of Node.js usage such as relational databases. This is about responsiveness under intensive CPU computation. A candidate should clearly see in what applications the effectiveness of Node.js is questionable and why this technology is not a silver bullet in each and every case.

  6. What previous experience do you have with Node.js? This question is a test on integrity. A candidate with no true practice in Node.js can hardly trick professional developers, and the ability to remember theoretical definitions should not be a ticket to the team. At the same time, this is not about performing tasks on the go with a paper and pencil or in some online editor. It is always better to give some “homework” assignments to a candidate to show that experience matters.

  7. Why do you believe you meet our expectations from a Node.js developer? The question encourages candidates to correlate their knowledge of the topic with both the architecture of the company and the job role. It is important to know how clearly a candidate sees the job description through the lens of interests of the company with regards to Node.js.

  8. What is in your opinion an ideal Node.js development workflow? Candidates should describe their vision of the entire process, beginning with identifying the problem and up to the delivery of code to production. Besides, when it comes to a senior developer, team workflow should be addressed: how to communicate with a remote team, how to solve conflicts, how to integrate different time zones, how to combine quick releases with the wishes of developers, etc. This may not be a compulsory one in the list of Node.js interview questions since many senior developers simply write code. But in general, understanding of a team workflow is expected from seniors.

  9. Which Node.js framework do you personally prefer? This specific question can say a lot about the true cognitive distance between the candidate and the Node.js technology. There are different tools that aid the management of data between servers and applications in the realm of Node.js. The most popular one is Express.js, but it’s not the only one candidates can choose. Developers who prefer, for instance, Hapi.js should be able to defend their choice: whether this is about scalability, minimalism, or any other characteristic of the framework.

  10. Do you have any interaction with Node.js beyond work? It is always useful to know how deeply candidates are interested in the technology they are working with: which relevant news channels they monitor, which open-source projects they participate in, which thematic conferences they attend, etc. A wide beyond-work experience in Node.js can add extra points to any candidate.

  11. What is your previous work experience? The question might seem irrelevant, but this is far from the truth. This one can reveal more about a candidate than all previous Node.js interview questions together. It is important not to approach this topic superficially, just for the show. Knowing any relevant information about the candidate won’t hurt.

  12. Do you have any questions to ask us right now? It is a good move for making candidates to re-evaluate their intention to work for the company when the interview is over. In case a candidate appears fairly weak for the job position, the issue can help both the candidate and the interviewer make up for the discomfort of the inevitable refusal. Besides, a suggestion to ask the employer anything disposes to more sincere revelations from candidates.


The above list of Node.js interview questions is not intended to be exhaustive. However, it can be a basis for a personal creative approach of any HR specialist to what we know as a job interview. This list needs to be supplemented by reviewing the code written by candidates. Almost all of them usually have some pieces of their own code that can be checked.

Since AnyforSoft has been engaged in advanced Node.js development for quite a while, the shared exemplary questions reflect our deep expertise based on real-life experience. We hope they will help you find a specialist to take on your project, and you can always contact us in case you have further questions.

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