Front End Developer Interview Questions and Answers for Interview Preparation

The hiring managers of FAANG and tier-1 tech companies frame Front End Developer Interview Questions to look for ??in-depth knowledge of HTML5, understanding of website design principles, testing, debugging, and advanced problem-solving skills. Practicing front end interview questions related to these topics will help you ace your tech interview.

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In this article, we’ll cover some common front end developer interview questions and answers. Front end developers are the creative people behind the translation of static designs into functional web pages, websites, and web applications. They deal with a website's user-facing code, using programming languages like JavaScript and HTML/CSS. It also involves collaborating with many different stakeholders.  

So, to uplevel your interview prep, you must brush up on your technical as well as soft skills. Read on for some important front end developer interview questions and answers.

Here's what we'll cover:

• Common Front End Developer Interview Questions and Answers
• JavaScript Front End Developer Interview Questions and Answers
• CSS Front End Developer Interview Questions and Answers
• HTML Front End Developer Interview Questions and Answers
• More Sample Front End Developer Interview Questions for Practice
• FAQs on Front End Developer Interview Questions

Common Front End Developer Interview Questions and Answers

Here are the most popular front end developer interview questions on webpage and web applications that will help you with your upcoming FAANG interview and every other tech interview.

Q1. How do you ensure that your website or web application is user-friendly?

It is one of the most crucial front end developer interview questions to analyze your understanding of usability and accessibility when designing experiences for end-users.

To ensure that a website/web application is user-friendly:

• Test web applications on various browsers and devices and check whether the experience is usable on all.
• Use popular screen reading software to see whether it is accessible for all users.
• Effective, consistent navigation.
• Review website using automated accessibility assessment tools.

Do you know what the job of a front end engineer at FAANG looks like? Check out these articles on Amazon and Facebook front end engineer roles and responsibilities.

Q2. What resources do you prefer to learn about the latest front end development trends and design?

A hiring manager explores soft skills involving inquisitiveness through such front end developer interview questions. Be specific in your answer.

The best ways to learn about the latest trends in web development are:

• Enrolling in continuing education workshops or online courses
• Participating in StackOverflow forums
• Subscriptions to front end development magazines

Q3. What are the best techniques you have used to increase the performance of a new website?

The most rewarding techniques to improve website performance are:

• Cleaning up excess plugins
• Upgrading web hosting plan
• Enabling Leverage browser caching
• Decreasing HTTP requests
• Enabling GZIP compression
• Minifying JavaScript and CSS files
• Optimizing images
• Changing website theme

Q4. What is a version control system? Which VCS are you familiar with?

Front end developer interview questions also include explanations and comparisons of various types of version control systems or VCS. VCS is a software tool that helps software teams manage changes to source code over time.

It is used for all code, files, and assets that multiple team members will collaborate on from all around the world. Thus, it accelerates product delivery. Types of VCS are: Local, centralized, and distributed VCS.

Some popular VCSs are:

• Git (distributed)
• Mercurial (distributed)
• Subversion (centralized)

JavaScript Front End Developer Interview Questions and Answers

When it comes to front end development, you are expected to have deep expertise in JavaScript. Here are some common JavaScript interview questions for front end developers.

Q1. What is the difference between let, const, and var?

Front end developer interview questions cover various variables in JavaScript. Variables are containers for strong values. Earlier, var was the only variable in JavaScript. In ES6, const and let emerged as additional options.

To get a deeper understanding of the differences between var and let, read this article.

Q2. How does the “this” keyword work in JavaScript?

In JavaScript, “this” is set to the window object. Its value depends on whether or not you are in strict mode. A strict mode “this” will be undefined in a top-level function, while a non-strict mode “this” will be the window object. The value of “this” can be overwritten with the bind method.

Q3. How can you traverse the DOM with JavaScript?

In JavaScript, you can get a DOM node with either getElementById or querySelector. Next, you can call .childNodes, which returns a NodeList. You can traverse the DOM by iterating through the childNodes and calling .childNodes on each one. Also, checking any node's parentNode allows you to walk your way back.

Q4. What is the difference between mutable and immutable objects?

JavaScript Interview questions related to objects are also pretty common at front end developer interviews. Here is the major difference between mutable and immutable objects with examples of each kind:

Q5. What tools do you use to debug JavaScript code?

Debugging and its tools are amongst the most common front end developer interview questions. Although all modern browsers have a built-in JavaScript debugger, the best JavaScript debugging tools are:

• Postman
• ESLint
• JS Bin
• JSON formatter and validator
  

CSS Front End Developer Interview Questions and Answers

Knowledge of advanced CSS is a must to crack front end interviews. Here are some important CSS front end developer interview questions.

Q1. What is a CSS float? State an example of its usage.

A CSS float is a positioning property used with images and layouts. It directs the browser to place a particular element to the right side or the left side of the container. It is useful when a web developer develops a page that dynamically resizes based on the user resolution.

Q2. What is CSS specificity?

Many front end developer interview questions will require you to know about CSS selectors. Through specificity, a browser decides which CSS property values are the most relevant to an element, and they will be applied. CSS specificity refers to the importance of every selector. It is based on the matching rules composed of different sorts of CSS selectors.

Q3. What is FlexBox? What is the use of FlexBox?

Flexbox or Flexible Box is a W3 specified layout system for CSS. It allows the automatic arrangement of responsive elements inside a container depending upon the screen size.

CSS flexbox layout allows:

• Easy HTML formatting
• Makes it simple to align items vertically and horizontally using rows and columns
• Items easily "flex" to different sizes and fill the available space making responsive design easier.

Q4. What is a CSS grid? What is the difference between FlexBox and CSS Grid?

CSS Grid layout is a W3 system for making entire page layouts. It creates complex responsive web design grid layouts easily and consistently across browsers. While Grid is ideal for grids and full pages, flexbox is great for groups of items on a page.

The basic difference between CSS Flexbox and Grid layout is that flexbox allows a one-dimensional layout — either a row or a column. On the contrary, Grid allows a two-dimensional layout — rows and columns simultaneously. Such questions on comparing two items or features are common at front end developer interviews.

Q5. What does the CSS preprocessor do? What are the different CSS preprocessors?

A CSS preprocessor is a program that allows you to generate CSS from the preprocessor's unique syntax. CSS preprocessors compile the code written using a special compiler. Next, they create a CSS file, which the main HTML document can reference. The popular CSS preprocessors are:

• Sass
• LESS
• Stylus

Q6. What are pseudo-elements?

Pseudo-elements are certain keywords that allow you to style and specify specific parts of an element rather than the entire thing. For instance, you can style before, the first letter, or the line of a component.

For more CSS questions, check out the top 25 CSS Interview Questions.

HTML Front End Developer Interview Questions and Answers

It goes without saying — you have to be adept at HTML to crack front engineering interviews. Here are some common interview questions on HTML.

Q1. What is the difference between a tag and an attribute?

Here are the main differences:

Q2. What does DOCTYPE do? Is it mandatory?

The DOCTYPE declaration is a mandatory instruction to the web browser. It tells the browser the version of HTML in a webpage, ensuring that the webpage is parsed the same way by various web browsers. Without the DOCTYPE, the browsers enter Quirks Mode.

Q3. What are empty elements in HTML?

An empty element/self-closing element/void element in HTML is the one that cannot have child nodes, i.e., it doesn't have any embedded or text elements. Example: the <br> element, which represents a line break.

Q4. What does semantic HTML mean?

Semantic HTML means using the most appropriate tag for a task. Semantic markup is HTML that introduces meaning to the web page instead of a simple presentation. For example, a <p> tag implies that the enclosed text is a paragraph.

Did you know that the average salary of a Google Front End Developer is $156,806 per year? Read these articles on Google and Amazon front end developer salaries to learn more.

More Sample Front End Developer Interview Questions for Practice

Here are a few more front-end developer interview questions on JS, CSS, HTML, and web design for your practice:

1. What are the pros and cons of extending built-in JavaScript objects?
2. What are the benefits of using spread syntax, and how is it different from the rest of syntax?
3. Give an example for destructuring an object or an array.
4. What are the ways to integrate CSS into an HTML page?
5. How would you fix browser-specific styling issues?
6. What do you know about styling SVG?
7. What is the use of the Clearfix CSS property?
8. What is progressive rendering?
9. Explain the difference between layout, compositing, and painting.
10. What are the differences between Long-Polling, Server-Sent Events, and Websockets?
11. What are the best tools to find a performance bug in your code?
12. How can you test JavaScript code?

This completes the list of important front end developer interview questions and answers. In addition to these, you must also practice some coding problems to ace your front end interview.

FAQs on Front End Developer Interview Questions

Q1. How do I prepare for front end developer interview questions?

To prepare for front end developer interview questions, practice coding, learn about JavaScript, HTML, CSS, algorithms, and data structures. Also, research about the tech company you are applying for. Having a strong command on these topics can help you crack every interview with ease and confidence.

Q2. What are some must-learn topics for answering front end developer interview questions?

If you are a front end developer, you are expected to know HTML, CSS, JavaScript, ES6, Chrome DevTools, and Git version control.

Q3. Do I need to know algorithms and data structures for front end developer interview questions?

Yes. You must know basic algorithms and data structures for front end developer interview questions. Hiring managers expect you to know things like filtering and sorting a data set.

Q4. What front end skills do you require for front end developer interview questions?

To ace front end developer interview questions, you should be well-versed with HTML, CSS, JavaScript, frameworks, libraries, version control, cross-browser testing, web performance optimization, and SEO. To crack FAANG interviews, you should also be good at solving coding problems and front-end-based scalable system design questions.

Q5. Are front end developer interview questions easy?

Front end developer interview questions might look easy, but they are not that simple. They require a thorough knowledge of various languages and technologies. Therefore, you must have a solid preparation strategy to ensure you cover all ground.

Ready for your Front End Developer Interview?

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