10 Web Developer Engineer Interview Questions and Answers for frontend engineers

flat art illustration of a frontend engineer

1. What motivated you to become a frontend engineer?

From a young age, I was always fascinated by the way websites worked and how they were designed. As I grew up, my interest in coding and creating beautiful and functional websites only increased. In college, I took several courses in computer science and programming, which solidified my passion for web development.

During my first job as a web developer, I was tasked with improving the loading speed of a website. By optimizing images and code, we were able to reduce the website's loading time from 5 seconds to just 1.5 seconds. This not only improved the user experience but also increased the website's organic traffic by 25% over the next few months. Seeing the tangible impact my work had on a website and its users was incredibly fulfilling.

Additionally, being a front-end engineer allows me to merge my passion for design and coding. Creating visually stunning and user-friendly websites is something I enjoy doing and seeing the end product live on the web is truly satisfying.

  1. My interest in web development started in my childhood
  2. Computer science and programming courses at college deepened my interest
  3. Reducing website loading times by optimizing images and code during my first job improved user experience and traffic
  4. Merging my passion for design and coding as a frontend engineer is incredibly fulfilling

2. What criteria do you use to decide which frameworks or libraries to use?

When it comes to selecting which framework or library to use, I consider the following criteria:

  1. Functionality: I look for frameworks or libraries with the features required to achieve the project's goals. For example, in a recent project, we needed a mapping interface, so we opted for Leaflet.js, which provided easy-to-use mapping options.
  2. Popularity: I consider how commonly used a framework or library is. Popular options have a large community of developers who contribute to the project's ongoing development and provide resources, support, and bug fixes. In a previous project, we chose React because it was widely used, and we could easily find resources and support online.
  3. Performance: I analyze the load time and execution speed of the frameworks or libraries. In one project, we used jQuery for its easy-to-use DOM manipulation, but later switched to Vanilla JS to improve the site's performance.
  4. Maintainability: I prefer frameworks or libraries with regular updates from their maintainers. This ensures that they remain inspired and improved, which guarantees I can easily maintain the code and quickly adapt to future changes.
  5. Learning curve: I consider the ease of learning to use the framework or library. For example, we chose Angular instead of Vue due to our team's familiarity with Angular, making it easier to learn and develop faster.

Using these criteria has ensured that my team and I choose the most suitable framework or library in every project. In my previous project, we used React and achieved a 73% increase in the website speed, reducing the load time from 5 seconds to 1.5 seconds, resulting in a 59% increase in our conversion rates.

3. How do you approach problem-solving when working on a project?

When faced with a problem while working on a project, I follow specific steps to find a solution. First, I analyze the problem, breaking it down into smaller components to gain a better understanding. Then, I research possible solutions or approaches, utilizing my past experiences and best practices.

  1. Assess the problem: I first try to understand the problem and its scope. I take some time to study the documentation and previous codebase to get a better context.
  2. Break it down: I proceed to break the problem into small, manageable chunks to tackle each issue sequentially.
  3. Research and Learn: Depending on the situation and resources available, I research the problem online, books or with the team to find existing solutions, gather insights, learn new techniques or libraries.
  4. Develop a strategy and prototype: I then develop an approach or strategy on how to solve the problem. If necessary, I create a prototype to experiment with different solutions once I have some implementation ideas in mind.
  5. Test and Debug: Once the prototype is created, I test it, and I identify the bug and clarify any confusions. I make sure the code meets the requirements and is optimized.
  6. Iterate and Improve: I strive to make the code leaner and more optimized as I move forward, trying to incorporate feedback from colleagues, stakeholders, or users.
  7. Document and Share: Finally, I document my solution, detailing the steps I followed, the insights I gained, and the decisions I made, to help others in the future.

This process has proven to be effective, and it has helped me solve numerous problems while working on different projects in the past. For instance, while working on a previous project, we were faced with a performance issue that was slowing the app down. I followed the steps outlined above and managed to optimize the code, which led to a 50% increase in overall performance. As a result, our app was more efficient and user-friendly.

4. What do you think are the top 3 skills a frontend engineer should possess?

One of the most important skills a frontend engineer should possess is strong proficiency in HTML, CSS, and JavaScript. These three programming languages are the building blocks of the modern web, and being able to work with them effectively is essential to creating high-quality websites. In addition, a frontend engineer should have excellent design skills. They should be able to create visually appealing layouts, choose appropriate color schemes, and create graphics and icons that enhance the overall user experience. Another essential skill for a frontend engineer is knowledge of responsive design principles. With more and more web traffic coming from mobile devices, it's important to create designs that adapt to different screen sizes and resolutions. Being able to create responsive designs that look great on both desktop and mobile devices is becoming increasingly important in modern web design. For example, I have worked on several projects where I had to implement responsive designs. One project was a website for a local restaurant. The website received a lot of traffic from mobile devices, so ensuring that the design was responsive was a top priority. I used media queries and flexible grids to create a design that looked great on all devices. As a result, the website's bounce rate decreased by 15% and on average users spent 30% more time on the website. Overall, a combination of programming skills, design skills, and knowledge of responsive design principles are crucial for frontend engineers in order to create high-quality websites that meet today's web design standards.

5. Can you describe a project that you have worked on and how you were able to optimize its performance?

During my time at my previous company, I was tasked with optimizing the performance of a website that was experiencing long load times and poor user engagement due to slow loading pages.

  1. To start with, I conducted a thorough audit of the website's code and identified several areas that could be improved upon, such as uncompressed images and redundant JavaScript libraries.
  2. Next, I implemented a content delivery network (CDN) to reduce server response times and minimize the impact of server downtime.
  3. I also utilized browser caching and compression techniques to improve the website's page load times, resulting in a 25% reduction in page load times.
  4. To ensure that the website's performance remained optimized, I set up automated testing and monitoring tools to track and analyze user engagement and identify any potential bottlenecks.

Thanks to these optimizations, the website saw a 30% increase in user engagement, a 15% reduction in bounce rates and an overall improvement in search engine rankings, leading to an increase in organic traffic of 20%.

6. How have you kept your technical knowledge current with the constantly evolving front-end technologies?

Staying current with rapidly evolving front-end technologies is a top priority for any web developer engineer, and I am no exception. To stay up to date with the latest trends and developments, I rely on several different resources and techniques, including:

  1. Reading industry blogs and publications: I regularly read blogs and publications such as CSS Tricks, Smashing Magazine, and A List Apart to learn about new tools, techniques, and best practices.
  2. Participating in online communities: I am an active member of several online communities, including the CSS-Tricks forums, Reddit webdev community, and Stack Overflow. These communities provide a wealth of knowledge and resources, and I contribute by sharing my own experiences and insights.
  3. Attending conferences and meetups: I attend web development conferences and meetups whenever possible, in order to learn from other developers and gain inspiration for new projects. In the past year, I attended Frontend NE, Scotland CSS, and CSS Day.
  4. Trying new tools and techniques: I am always willing to experiment with new tools and techniques to stay ahead of the curve. For example, I recently began working with CSS Grid to create more complex layouts, and I participated in the beta testing of Sketch 55 to try out new features.

By staying informed and engaged with the web development community, I am able to keep my skills and knowledge current and ensure I am always delivering the best work possible to my clients.

7. What is your preferred coding style, and what are some common coding practices that you regularly follow?

My preferred coding style is to write clean and organized code that is easily understandable to my team and future developers. I believe that readability is essential, so I consistently follow proper indentation and commenting conventions to make my code as clear as possible.

One common practice that I regularly follow is utilizing version control systems like Git to keep track of changes and collaborate effectively with my team members. This has helped me coordinate efficiently and quickly resolve code conflicts during team projects.

Another coding practice that I believe is crucial is writing unit tests for all of my code. This ensures that my code is reliable and consistent, and it helps me pinpoint any errors or bugs during development. In the past, by implementing strong unit tests, I was able to catch and fix critical bugs that were missed during manual testing, which saved time and resources.

Lastly, I always aim to strike a balance between elegance and practicality in my code. While I strive to write beautiful and eloquent code, I am also mindful of maintaining efficiency and scalability in my solutions. By doing so, I was able to optimize an application that previously had constant crashes, reducing the crash rate by 70%.

  1. Write clean and organized code
  2. Utilize version control systems like Git
  3. Write unit tests for all of my code
  4. Strike a balance between elegance and practicality in my code

8. In your opinion, what are some of the best tools and techniques for debugging and troubleshooting front-end issues?

Debugging and troubleshooting is an essential part of front-end development, and by using the right tools and techniques, we can save a lot of time and effort. In my opinion, some of the best tools and techniques for debugging and troubleshooting front-end issues are:

  1. Google Chrome Developer Tools: Google Chrome Developer Tools is a set of web authoring and debugging tools built into Google Chrome. With this tool, we can inspect and debug HTML, CSS, and JavaScript. We can also use it to diagnose network issues, performance problems, and memory leaks. Additionally, it can help us to identify unused CSS, which can significantly improve page speed load times.
  2. Visual Studio Code Debugger: Visual Studio Code Debugger is an excellent tool for debugging JavaScript code. It allows us to step through the code line by line and set breakpoints to stop the code at a particular point. We can also configure the debugger to watch specific variables and properties, which can be helpful for tracking down tricky issues.
  3. Linting tools: Linting tools can analyze our code for common errors, such as syntax errors and undefined variables. One example of such a tool is ESLint. By using these tools, we can catch errors before they cause trouble, which can save us a lot of time in the long run.
  4. Network analysis tools: Network analysis tools can help us diagnose performance issues by analyzing network delays, request sizes, and server response times. For example, we can use the Network tab in Google Chrome Developer Tools to identify slow-loading assets or integration issues with third-party services.
  5. Debugging remote devices: As more users access websites from different devices, debugging and troubleshooting issues on these devices is becoming increasingly important. Tools like BrowserStack can help us to easily test our site on a wide range of devices and browsers, including mobile devices, which can help us to identify and fix issues specific to these devices.

By using these tools and techniques, we can save a lot of time and effort when debugging and troubleshooting front-end issues, which can lead to better-performing websites and happier users.

9. How would you optimize a website for performance, and what key metrics would you track?

Optimizing Website Performance and Tracking Metrics

As a web developer engineer, optimizing website performance is a crucial task to ensure that users have a seamless experience while browsing the site. Here are the key steps I take:

  1. Minimizing HTTP Requests: To reduce the number of HTTP requests, I combine multiple stylesheets into one and use CSS sprites for images. This can reduce loading time by about 30%.
  2. Caching: To speed up the website even further, I use browser caching, which stores frequently used files on the user’s device, reducing the need for repeated requests. This can decrease load time by up to 75%.
  3. Compressing Files: Compressing files can help reduce the time it takes to download them. I use Gzip, which can reduce file sizes by up to 70%. This can lead to much faster page load times.
  4. Optimizing Images: Images can be a significant factor for slowing down a website. To optimize images, I use tools like Photoshop or plugins like WP Smush, which compresses images without sacrificing quality. This can lead to a 50% reduction in file size and faster page load times.

After the site is optimized, it’s essential to track key metrics to ensure it’s performing optimally. Here are the key metrics I track:

  • Load Time: I use tools like GTMetrix or Google PageSpeed Insights to monitor load time. A fast load time is essential for search engine rankings and user experience, so I aim for a load time of around 2 seconds or less.
  • Bounce Rate: Bounce rate is the percentage of users who leave the site after only visiting one page. A high bounce rate can signal that the site is slow or not user-friendly. I aim for a bounce rate of less than 50%.
  • Conversion Rate: Conversion rate is the percentage of visitors who take action on the site, such as making a purchase or filling out a form. A high conversion rate is critical for e-commerce sites, so I track this metric carefully.
  • Error Rate: Finally, I monitor the error rate to ensure that the site is functioning correctly. Error rates should be less than 0.5%, indicating that users are not running into issues while browsing the site.

By following these steps and monitoring these metrics, I can ensure that the site is optimized for performance and providing an exceptional user experience.

10. Finally, what are some of the challenges you’ve faced when delivering web content across multiple devices, and how did you overcome them?

As a web developer engineer, I have faced several challenges when delivering web content across multiple devices. One of the main challenges is ensuring that the website is responsive and can adapt to varying screen sizes.

  1. One approach I have used to overcome this challenge is through the use of CSS media queries. By setting different styles for different screen sizes, I can ensure that the website is optimized for each device. For example, I may set a breakpoint for mobile screens and adjust the font size and layout to make it more readable on a smaller screen.
  2. Another challenge is ensuring that images and other media are optimized for different devices to avoid slow load times. To overcome this, I use tools such as Google's PageSpeed Insights to identify optimization opportunities. I optimize images and compress files to reduce their size while maintaining quality.
  3. Finally, ensuring compatibility across different browsers and operating systems is also a challenge. I address this by testing my web content across different platforms using browser testing tools such as BrowserStack. These tools allow me to ensure that my web content is compatible with a wide range of devices and platforms.

By taking these steps, I have been able to successfully deliver web content across multiple devices without sacrificing user experience. For example, on a recent project, using these techniques, I was able to decrease page load times by 30% and increase mobile user engagement by 20%.


Congratulations, you've made it through 10 interview questions for web developer engineers! As you prepare to land your dream remote frontend engineer job, don't forget to write a compelling cover letter to introduce yourself to potential employers. Crafting an impressive CV is also important, so check out our guide on writing a resume for frontend engineers. If you're actively searching for a new remote frontend engineer job, look no further than Remote Rocketship's job board. Our website is specifically designed to help match you with great remote opportunities. Good luck with your job search!

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