Software

10 questions full stack developers should expect in a job interview

Full stack developers are in high demand. Here are some tips on how to answer the most common questions and land the right job.

Full stack developers top the list of best tech jobs in America in 2018 in terms of salary, number of job postings, and opportunities for growth—and are also one of the hardest to fill tech positions. With an average base salary of $$111,640, companies that are investing in this position want to make sure they bring the right candidate on board.

"When I ask interview questions, I am not looking for a particular answer or expertise in each one," said John Maglione, senior talent acquisition specialist at WWT Asynchrony Labs. "Rather, these questions help me gain a solid understanding of where the candidate may be experience-wise with relation to the length of their career, because tenure, doesn't always translate to a deeper understanding of the discipline."

Here are 10 interview questions that full stack developer candidates may expect to be faced with in their job search.

SEE: IT Hiring Kit: Programmer (Tech Pro Research)

1. What's your favorite language, and why?

This is a good question to warm a candidate up before diving into more technical ones, said Jason Ayachi, co-founder of RampUp.

"For a full stack developer, we're looking for them to answer with a variety of languages rather than just having one favorite language," Ayachi said. "We also love to hear that they're playing around with a few new languages. This shows us that they're really engaged with the industry and have a curious-passionate mind."

2. Provide an example of a web application that you've built and what technologies were used to build it. What considerations did you make when deciding on the tech stack to use?

"This question is asked to get a sense of how a developer thinks and also speaks to what considerations they make when settling on a toolset," said Paul Wallenberg, unit manager of technology recruiting services at LaSalle Network. "Interviewee should respond as specifically as possible, even if the decision was made because of pre-determined architectural standards or a company-mandated technology preference."

A related question might be whether or not a candidate considers themself heavier on the front-end or back-end, said Christy Cifreo, senior recruiter at Synergis. "Give an example of a recent project to include how and why you developed either on the front-end or back-end," Cifreo said. "We would want to get some basics of where they are most experienced. Depending on the specific job, we might be looking for someone that has more experience in one area over the other."

3. How do you stay aware of new technologies related to full stack web development?

This question is asked to find out how involved or uninvolved a candidate is in the technology community, Wallenberg said. Interviewees should respond by describing a few meetups they are part of related to JavaScript, or personal projects that they have displayed in GitHub, for example.

A related question might be, "What have you learned that's new in the last year?"

"The world of development is changing all the time—as the word 'development' suggests. Therefore, it is vital that a full stack developer has his or her finger on the pulse of what's happening," said Steve Pritchard, HR manager at Cuuver.com. "You need to be able to come back at the interviewer with a new software you have tested recently or a new skill you have acquired in the field. Showing that you have an up to date knowledge of development and that you are keen to keep learning, will show them that hiring you means their website will not be stuck in the dark ages with a full stack developer who hasn't learned anything new since 2010."

SEE: Job description: Java developer (Tech Pro Research)

4. Provide an example of when you found an inefficiency in someone else's code, and how you addressed it.

This question is meant to find out how good a candidate's quality assurance checking is, as well as how comfortable they are pointing out flaws or bugs to others, said Mike Lannen, founder and creative director of Eternity.

5. What is your familiarity with design patterns?

"Asking this question gives us an idea of how a candidate's background has prepared them to be able to understand common problems typically addressed in creating software, and how formal their understanding of maintenance and code reuse is," Maglione said. It also helps the employer gain an understanding of how much a full stack developer understands clean, readable code, he added.

6. Tell me about a time you've struggled to implement or debug something at each part of the stack.

"This is one of the few questions where it's good to talk about times you've struggled," Pritchard said. "Development is a complicated minefield in many ways, so pretty much every experienced developer has had problems with it of various kinds. If they haven't struggled, they aren't really all that experienced."

As a job candidate, you should explain why you struggled in as much technical detail as possible, and how you remedied the situation, Pritchard said. "This will show the interviewer that you have a grasp on why you had difficulties, that you learned from it, and that you understood the problem," he added.

A related question may be, "Tell me about the most puzzling programming challenge you solved over the past year, and how you tackled it."

"One way to respond to this question is to present yourself as someone who welcomes teamwork," said Jennifer Roddy Selden, national director of recruiter innovation and performance at Randstad Technologies. "Maybe the programming challenge you experienced required help from your coworkers. Explain to your interviewer how you tackled this obstacle as an individual, but in equal importance, how you were able to build team camaraderie during this task. Responding with this approach can position you as a strong cultural fit for the team."

7. What kind of role do you enjoy most?

For more senior developers, it's important to let a potential employer know how much you want to stay in a purely technical role, and how much you want to move toward management, according to Gary Verhaegen, a full stack developer at Sparrho. This helps make sure you are a good fit for the company.

A related question would be, "Do you enjoy working in a paired programming environment, or do you prefer to work alone?" This question can help determine how much team collaboration a candidate has experience with, Cifreo said.

8. How would you store a user's password for an online portal?

This question seems simple, yet quickly reveals a full stack developer's security knowledge, said Paul Leduc, director of technology at RingPartner. "There are lots of ways to store passwords, but only a few could be considered secure from front-end to back-end," Leduc said. "Ideally, a developer would be able to articulate which specific security features are essential and explain how the user's data would be protected from the UI through to the back-end and databases. This is also a great opportunity for a developer to highlight how she or he has handled a similar scenario in the past, which provides insight on character and helps the interviewer see how the candidate could be a culture fit."

9. What projects are you currently working on? What side projects are you working on?

The underlying question here is "How much do you code?" said Ayachi. "Good developers almost always have several side projects they're working on just for fun," he added. "One of our best candidates had designed a really in-depth analytics website for his daily burrito intake. It was really impressive."

10. What technologies, programming languages, and frameworks would you use if you had to develop a project from scratch in only one month?

The objective of this question is to challenge the candidate to answer a complex question in a short amount of time, said Cristian Rennella, vice president of HR and co-founder of elMejorTrato.com. "This way you can distinguish the best full stack developers, because those who can answer this question in a clear and simple way will be the most appropriate," Rennella said. "Those who have a difficult time to transmit their thoughts will be the least."

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Image: iStockphoto/seb_ra

About Alison DeNisco Rayome

Alison DeNisco Rayome is a Senior Editor for TechRepublic. She covers CXO, cybersecurity, and the convergence of tech and the workplace.

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