10 Frontend Infrastructure Engineer Interview Questions and Answers for frontend engineers

flat art illustration of a frontend engineer

1. Can you describe your experience with front-end build systems and package managers?


During my time at XYZ Company, I was responsible for leading the implementation of a new front-end build system using Grunt. Prior to this project, the development team was manually compiling all files, which led to inconsistencies and inefficiencies in their workflow.

After implementing Grunt, we saw a significant improvement in development speed and overall code quality. Our team was able to automate repetitive tasks, such as minification and concatenation of CSS and JavaScript files, and optimize image assets. By utilizing Grunt as our build system, we were able to reduce page load times and improve the user experience for our customers.

In terms of package managers, I have experience using both NPM and Yarn. I am proficient in managing packages and dependencies, ensuring compatibility between different versions and reducing the likelihood of conflicts. At my previous job, I led a project where we migrated our package manager from NPM to Yarn, resulting in faster and more reliable installations.

  1. Implemented Grunt as front-end build system, resulting in faster development times and improved code quality.
  2. Automated repetitive tasks such as minification and image optimization with Grunt, leading to faster page load times and enhanced user experience.
  3. Successfully migrated from NPM to Yarn as package manager, improving installation speed and reliability of dependencies.

2. How have you integrated front-end tools and frameworks with backend systems in previous projects?

Sample Answer:

In my previous projects, I have integrated front-end tools and frameworks with backend systems to create seamless user experiences. One example is a project where I integrated Vue.js with a REST API built on Node.js to create a dynamic e-commerce platform.

To accomplish this, I used Axios to make Ajax requests to the API, retrieving and displaying product information, user data, and cart items as needed. I also utilized Vuex for state management to ensure that the application remained responsive and efficient. Additionally, I implemented testing frameworks such as Jest and Enzyme to fully test the application's functionality and ensure that the front-end and back-end systems worked together seamlessly.

The result of these integrations was a smooth user experience that allowed customers to easily browse and purchase products. The application was fast and reliable, with little to no latency between the front-end and back-end systems. Overall, the project was a great success, and user feedback was overwhelmingly positive.

  1. Axios was used to make Ajax requests to the API.
  2. Vuex was used for state management
  3. Jest and Enzyme frameworks were implemented to test the application's functionality

3. What strategies have you used to optimize the performance of websites or web applications?

As a Frontend Infrastructure Engineer, optimizing the performance of websites and web applications is a critical part of my job. Some strategies I have used to achieve this include:

  1. Implementing caching mechanisms: Caching greatly improves the speed and speed of websites by storing frequently accessed files in the server's memory, reducing the time it takes to retrieve those files during subsequent requests. In one instance, I implemented caching in a large e-commerce platform, and it led to a 30% improvement in page load times.

  2. Load balancing: I have worked on websites that receive millions of visitors every day, and ensuring proper load balancing is essential to ensure that the website can handle the traffic without slowing down. By distributing the traffic among multiple servers, load balancing ensures that no single server is overwhelmed, thus improving the website's performance. I once implemented load balancing on a high-traffic website, and it led to a 50% reduction in latency and a 40% increase in throughput.

  3. Minifying files: Minifying is the process of removing all unnecessary characters from files, such as code comments, white spaces, and new lines. Minifying files reduces their file size and consequently reduces the time it takes to load them in the browser. In one project, I minified CSS and JS files, which resulted in a 25% reduction in file size, which led to an 18% increase in page speed.

  4. Image optimization: Images can take up a lot of space on a server, and loading them can be time-consuming. Image optimization involves compressing images without compromising their quality, thus reducing their size and improving their loading times. In one instance, I optimized images on a website, and it resulted in 40% faster loading times and improved the website's overall performance.

I have found that a combination of these strategies guarantees the best results in optimizing website and web application performance.

4. What tools and techniques do you use to ensure cross-browser compatibility?

As a frontend infrastructure engineer, ensuring cross-browser compatibility is crucial to the success of a project. The following are some of the tools and techniques that I use:

  1. BrowserStack: I use BrowserStack to test the website or application on different browsers and devices.
  2. Testing Tools: I also use testing tools like Selenium or Cypress to automate testing on multiple browsers and versions.
  3. Shims and Polyfills: In order to ensure that certain features work smoothly across different browsers, I use shims and polyfills to fill in the gaps.
  4. CSS Libraries: I also use CSS libraries like Bootstrap or Foundation, which have been designed with cross-browser compatibility in mind.

By using these tools and techniques, I have been able to ensure that the websites and applications I have worked on are functional and accessible across different browsers and devices. For example, in my previous job, I was responsible for ensuring that a web application was functional and accessible on Internet Explorer 11, Google Chrome, and Mozilla Firefox. Through my efforts, the application achieved a 99.9% cross-browser compatibility rating, which led to an increase in customer satisfaction and engagement.

5. How do you optimize site accessibility for users with disabilities?

One way to optimize site accessibility for users with disabilities is by incorporating proper semantic HTML tags. Using semantic tags such as
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