Front-End Developer Interview Questions and Answers

Front end developers are responsible for the client-side of web applications. The first thing a user sees and interacts with when they visit a website is the user interface. Front end developers ensure that the user interface does not just retain aesthetic value but even more, that it maintains high functionality and performance for an optimum experience for users.

This article explains various aspects of the front end developer interview process and particularly the front end interview questions that recruiters may ask and that candidates may expect.

The information covered here is drawn from our experience at ProCoders, being a top IT outstaffing company specializing in software engineering. ProCoders builds tailor-made teams to help our client companies scale software development, that is why we have great experience in making up front end engineer interview questions.

What Do You Need to Know Before Hiring a Front-End Developer?

• When hiring a front-end developer, it’s important to ensure that they have the necessary skills and experience to meet your project’s requirements. That is why it is always helpful to have someone with a tech background as part of the recruitment efforts. They should be tasked with drawing up relevant front-end coding interview questions to evaluate the fitness of candidates for the role.
  In addition to assessing your candidates’ coding abilities and portfolio, it’s crucial to discuss their familiarity with the best web application technology stacks for your particular needs. It’s essential to work with a developer who is well-versed in the latest technologies and can advise on the best options for your project.
• Determine ahead the crop of your team and if you would be hiring a mix of junior, mid-level, and senior developers. This will help in setting proper front-end engineer interview questions for more accurate evaluations.
• A front-end developer is responsible for the client-side and user interface of a software product in order to boost the performance of the application. If the job description extends beyond this, you should consider reviewing the roles or hiring a different professional.

• If you are hiring a team of developers, it is more helpful to simply hire an offshore software development outstaffing agency such as ProCoders to provide you with high-class professionals and infrastructure to build your software efficiently.
• Testing is crucial to the development process. Therefore place a priority upon front end testing interview questions for any skill level of the candidates.

Front End Interview Questions for Developers

Beginners Level Front End Developer Interview Questions (1-2 Years of Experience)

This section covers basic frontend coding interview questions for beginner developers. Of course, at this level, you can’t expect the developers to be proficient in all the technical areas of front end development yet. However, they should be able to answer the most essential questions concerning areas such as user-friendliness and the likes.

In what coding languages do you have the greatest experience?

First, a front end developer must be skilled in at least three or four specific programming languages, namely HTML, CSS, and JavaScript. HTML and CSS are the two most basic components of any website at all. Additional knowledge of JavaScript is required to be able to add better functionality and advanced features to the website.

Besides programming languages, what are other important skills that you have acquired?

Besides being able to code efficiently in the above programming language, a front end developer must also have a working knowledge of Content Management Systems (WordPress, Drupal, Joomla, Magento, etc.), technical Search Engine Optimization (SEO), cross-browser development, responsive and mobile design principles, etc.

Frontend interview questions may also cover soft skills. Soft skills that may also be required include problem-solving, critical thinking, and creativity skills, among others. To actually determine the relevant short skills that a candidate possesses, a short skills test may apply, since an interview is often not enough to fully reveal such info of a person’s personality.

What makes a website user-friendly and how will you design a user-friendly website?

Part of the responsibilities of a front end developer is to ensure that they build websites with optimal user experience. So, they usually have to work the most with a UX designer, among other professionals on the team.
Some factors that enhance the user-friendliness of a website include the following:

• Using an intuitive navigation bar
• Implementing responsive design layout for optimal mobile viewing
• The use of accessible features to make the website more inclusive of the physically challenged and the elderly
• Ensuring faster loading times.

How did you resolve a technical challenge that you have encountered in the past?

Pay attention to the candidate’s recount and award more points if the candidate cites their first-hand experience. The purpose of this question is to assess the candidate’s capacity for problem-solving and to have a feel of their approach to resolving challenges.

One of the most common challenges for developers is having to learn new technologies. Therefore, a typical perfect answer to this question would focus on a candidate’s learning challenges as well as the tools and methods they used to resolve the issues. Some front end testing interview questions may also feature in this section.

Mid-Level Front End Interview Questions (2-4 Years of Experience)

Examples of frontend coding interview questions for mid-level developers.Of course, a person at this stage is neither supremely skilled, nor a total novice. Therefore, the questions should reflect a balance between technical questions and fundamental knowledge questions.

How do you structure/organize CSS, HTML, and Javascript content?

Frontend interview questions in this regard aim to establish the robustness of a developer’s coding process and whether their methods align with global coding standards and best practices. Like every developer worth their salt knows, it is not enough that a program simply works, the code should be clean and well-organized too.

Good code organization reflects in how a developer neatly writes code, keeps separate files for style sheets, functionality, content, etc., and ensures that updates can be flexibly made. Most importantly, since every developer has their own ideal structure, a candidate should be able to justify why they organize their code in a specific way.

What are some methods to decrease page load time and speed up the website?

The performance of a website is the most important factor in front end development. A front end developer should be skilled enough in ways to make a website load faster. Some of the ways in which front end developers boost the performance and speed of a website include the following:

• Compress heavy images to optimize them
• Reduce external HTTP requests by removing unnecessary images, code lines (JavaScript and CSS, particularly), and plugins.
• Minify JavaScript, CSS, and HTML code lines. If the minified version is hard to read, you may simply use it for production while keeping a cleaner version for development.
• Use prefetching or prerendering to load resources before they are needed

What are some testing best practices in front end development?

Front end testing interview questions are crucial. A good developer (front end, back end, full stack) must be familiar with testing processes and identify how different methods of testing achieve different results. For example, manual testing for web applications and automated testing are common among developers, so your candidate should know what that is and what method (or methods) will fit your project best.

It features unit testing, functional testing, and end-to-end testing. Unit testing analyzes individual parts of the code while a functional test analyzes the interaction between different parts of the code. The latter is also called an integration test. The end-to-end test compares the front end and the back end of the application.

Although testing is listed under mid-level, really, front end testing interview questions can be asked for any level of developers. Testing itself has multiple levels; so you can still adapt the questions for the relevant skill measure and experience.

Advanced Level Front End Developer Interview Questions (More 4 Years of Experience)

List of front end engineer interview questions for advanced level developers and engineers. Questions for senior developers need to be highly practical as you want to understand how the person would handle highly technical parts of a project. There is an implicit assumption that senior developers are well-versed in the basics already. So, you need not bother with those sorts of questions.

How and when can you use JavaScript functions?

The most common JavaScript functions include .forEach(), .map(), .filter(), .reduce() and .find().

• The forEach function is used in for loops to make the code more easily readable.
• The map function is for transforming and creating new arrays
• The reduce function eliminates other elements from an array to reduce it to a single value.
• The filter function is used to create new arrays with the callback feature
• The find function is used to determine the value of the first element in an array that fulfills an established condition.

What are HTTP methods and how are they used?

Take note that these are two frontend interview questions fused into one. Pay attention to how the candidate answers each part. HTTP methods are requests to specify the performance of a certain action and facilitate smooth interaction between the client-side and the server-side. Most of these methods are verbs. Hence, they are commonly known as HTTP verbs. Some of the most popular methods include:

• GET: these requests are used to retrieve data
• HEAD: performs the same function as the GET method but results are returned without the response body
• POST: these requests are used to send data
• DELETE: according to its name, these requests are used to delete specified resources
• OPTIONS: these requests return data and specify the communication options for some specified resource

What are the benefits of using a CDN?

Using a content delivery network can help you to improve the performance of a website. It also provides security by offering protection against DDoS attacks.

The highest benefit of using a CDN is that it results in optimal loading speeds, boosting the reliability and functionality of the website. Some of the most popular CDNs in use in the world right now include Cloudflare, Microsoft Azure, Google Cloud, Amazon CloudFront, etc.

How to Prepare for a Front End Developer Interview (if you are a Developer)

• Ahead of the interview, try to find out the format it will take in order to prepare well and even simulate interview scenarios. Some interviews might feature a live test and things like that.

• As a front end developer, you should definitely expect front end developer interview questions relating to HTML, CSS, and JavaScript, which all form the building blocks of web application development. Even if you are a beginner, you should at least, understand the basics
• Finally, don’t prepare for front end interview questions alone. Interviewers may ask you questions about general computer knowledge. Don’t be thrown off balance.

How to Prepare for a Front End Developer Interview (if you are an Employer)

• Evaluate their portfolio and look out in particular for relevant industry experience or, if the developer has never worked in your industry, transferable skills and knowledge from other sectors that they may have worked.
• Ask them specific front end developer interview questions regarding what they would do to improve your website or application. It is expected that a candidate must be familiar with your company and its products. Therefore, they should come with some basic ideas or a general overview of how they will make an impact on the company. This is crucial for senior developers mostly.

• Talk to the developer’s past clients/employers to determine what the candidate’s work ethic is like. It might also provide some context for the front end engineer interview questions to ask the candidate during the interview.
• Don’t forego testing for soft skills critical to development success. Development is technical but most employers make mistakes when they focus too much on the technical side, to the detriment of analyzing important soft skills such as critical thinking, communication, problem-solving, teamwork, leadership, etc.
• A good front-end developer should not only know how to code, but they must also be smart and know how to apply creative solutions to problems. They should be skilled in implementing responsive design, testing and debugging, boosting site performance, etc.

Conclusion

Front end development is a critical part of the web development process. Therefore you need to hire carefully. On Upwork, for instance, hiring front end developers costs an average of $15 to $35 per hour. To discover the best professionals, you need to be well prepared to ask the right frontend coding interview questions.

To find a more optimal approach to hiring front end developers and particularly, building a development team, it is better to hire an outstaffing agency offshore like ProCoders, operating from Ukraine. This helps to reduce your hiring costs while maintaining the high quality of the project. At ProCoders, we have developers available already but you are also free to conduct your own frontend interview questions and see that they are of high quality. Talk to us today!