170 UI Developer Interview Questions for Experienced Candidates

UI developers use front-end technology to bring creative software concepts to life. They are responsible for developing user interfaces that clearly communicate the backend capabilities of the program. In simple words, UI developers are front-end developers who build the user interface or the front end of a website. So, in many ways, they act as the final bridge between the product and the customer.

If you are gunning for a UI developer role, when you start your interview prep, be sure to check out our technical interview checklist, interview questions page, and salary negotiation e-book to get interview-ready!

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In this article, we lay out details about what you can expect at a UI developer interview. Here’s an outline of what we have covered:

• What’s Unique About a UI Developer Interview Process?
• Topics to Prepare for UI Developer Interview
• UI Developer Interview Questions
• UI Developer Behavioral Interview Questions
• UI Developer Interview FAQs

What’s Unique About a UI Developer Interview Process?

The structure for UI developer interviews is slightly different from the other tech interviews at FAANG companies. Candidates are tested for their coding skills, behavioral skills, as well as design skills. Most of the technical questions are based on front-end coding.

UI Developer Interview Process at FAANG Companies

The UI developer interview process is quite similar in all tier-1 tech companies and comprises these main rounds of interviews:

1. Front-End Machine Coding Round
2. Problem-Solving and DSA (Data Structures and Algorithms) Round
3. Javascript and Front-End Technologies
4. Front-End System Design Round
5. Hiring Manager Round

Topics to Prepare for UI Developer Interview

To crack the UI Developer Interview, you need to have a strong background in computer science concepts, along with the front-end frameworks.
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Front-End Concepts:

• HTML and CSS
• JavaScript
• Design patterns

Computer Science Concepts:

• Data structures
• Searching and sorting

As a UI Developer, you also need to have an in-depth knowledge of user interface development frameworks like:

• HTML
• CSS
• JavaScript
• AngularJS
• ReactJS
• VueJS
• Typescript
• AJAX

UI Developer Interview Questions

UI developer coding interview questions include topics like algorithms, data structures, and large-scale distributed systems. You also need to practice UI developer angular interview questions and Javascript interview questions for UI developer interviews. We will cover sample interview questions, and answers for UI developer experienced candidates on each of these topics in the sections ahead.

Common UI Developer Interview Questions and Answers

1. What’s the difference between a UI developer and a UX developer?
‍
The difference between a UI developer and a UX developer is as follows:
‍

UI Developer:‍

• A UI Developer takes care of the designing part of the visual elements, through which one can navigate through the Webpage.
• They must have sufficient business and design knowledge to avoid compromising the business objectives and design purposes.

UX Developer:

• A UX Developer improves the quality of user interaction with the company and its product.
• They must use feedback from customers, user data, and usability results in the design to improve the overall user experience.

2. What can you do to increase page performance?
You can increase the page performance by:

• Reducing the image size
• Clearing the cache
• Reducing the external HTTP Requests
• Coding your site for mobile
• Removing unnecessary widgets

3. What are the effects methods used in jQuery?
Following are some effects methods used in jQuery:

• show(): It displays selected elements.
• hide(): It hides the selected elements.
• toggle(): It shows or hides the selected elements, i.e. it toggles between hide() and show() methods.

4. List the types of filters in AngularJS.
Types of filters used in AngularJS are:

• currency: Format a number to a currency format.
• date: Format a date to a specified format.
• filter: Select a subset of items from an array.
• json: Format an object to a JSON string.
• limit: To Limit an array/string, into a specified number of elements/characters.
• lowercase: Format a string to lowercase.
• number: Format a number to a string.
• orderBy: Orders an array by an expression.
• uppercase: Format a string to uppercase.

5. How do you optimize a website’s assets?
You can optimize a website’s assets by:

• File concatenation
• File compression
• CDN Hosting
• Offloading assets
• Reorganizing and refining code

6. What is the difference between a document and a window?
The Window is the first thing that loads into the browser. It has properties like inner width, inner height, length. The Document gets loaded inside the Window object. It is similar to HTML, PHP, and other documents which are loaded into the browser.

7. What is the difference between a front-end developer and a UI developer?

Front-end developer:
Front-end developers create the client-side of the web interface and make sure all the website’s elements work correctly.

They focus on finishing the complete development process according to the integration of all web application pages.

Their skillset is a superset of a UI developer’s skill set.

UI developer:

UI Developer makes everything on the site look user-friendly.
They focus on the webpage interface elements such as the buttons, menus, and others, not as a complete project.
Their skillset is a subset of a front-end developer’s skill set.

8. Name some plugins available in the bootstrap jQuery plugin library.

Here are some of the plugins available in the bootstrap jQuery plugin library:
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• Alert
• Affix
• Button
• Carousel
• Collapse
• Dropdown
• Modal
• Popover
• Scrollspy
• Tab

UI Developer Interview Questions on Front-End System Design

Below is a list of common front-end systems design questions asked in the technical interview:

1. Design a proximity server.
2. Design a client-server application that lets people play Chess on a social network.
3. How would you design a search engine?
4. Design a URL shortening service like bit.ly.
5. Design a traffic control system.
6. Design a limit order book for trading systems.
7. Design a parking lot.
8. Design an autocomplete feature for a search engine.
9. Design an API rate limiter.
10. Design a ticketing management system for a theatre.

UI Developer Interview Questions and Answers on Data Structures and Algorithms

When it comes to data structures and algorithms, you can expect questions based on the following topics at the interview:

• Arrays
• Trees
• Stacks
• Recursion
• Binary Search
• Insertion Sort
• Bubble Sort
• Selection Sort
• Breadth-First Search
• Dynamic Programming
• Divide and Conquer
• Stacks and Queues

Questions:

1. Find all palindromic decompositions of a given string s. (Solution)
2. Given a variety of coin types defining a currency system, find the minimum number of coins required to express a given amount of money. Assume an infinite supply of coins of every type. (Solution)
3. Sort a given singly linked list in ascending order. (Solution)
4. Given ‘n’ pairs of numbers where: In each pair, the first number is smaller than the second number. If c<f, a certain pair [a,b] takes numbers from two different pairs [c,d] and [e,f].
5. Write a program to find the longest subsequence in two given strings, ‘str1’ and ‘str2’.
6. You’re given two strings, ‘S’ and ‘K.’ Write a program to find the longest common substring.
7. Write a code to convert a given set of integers into their Roman number equivalents.
8. Write a program to find out if a given number “N” is sparse. (A number is said to be sparse if no two bits are in binary representation).
9. Write a program to find the lowest common ancestor of two nodes of a given binary tree “B” with unique values.
10. Given a binary tree “B” with unique values, write a program to find: 1. The longest consecutive sequence. 2. The length of the longest path comprising connected nodes with consecutive values.
11. Given K sorted arrays arr, of size N each, merge them into a new array res, such that res is a sorted array.
12. Given a list of meeting time intervals consisting of start and end times [[s1, e1], [s2, e2], ...] (si < ei). You need to complete canAttendAllMeetings function and return 1 if a person can attend all given meetings else 0.
13. Given an array of numbers nums of size n, find an array of numbers products of size n, such that products[i] is the product of all numbers nums[j], where j != i.
14. Given a string s containing a set of words, transform it such that the words appear in the reverse order. Words in s are separated by one or more spaces.
15. Given a sequence, return its next lexicographically greater permutation. If such a permutation does not exist, then return it in ascending order.
16. Try to solve the problem with a constant amount of additional memory.
17. You are given alphanumeric strings s and t. Find the minimum window (substring) in s, which contains all the characters of t.
18. You are given an array of integers, arr, of size n, which is analogous to a continuous stream of integers input. Your task is to find K largest elements from a given stream of numbers.

UI Developer Front-End Machine Coding Interview Questions

Here are some of the most frequently asked front-end machine coding questions asked during a UI developer interview:

1. Build a front-end program from scratch using CSS, HTML, Javascript.
2. What do you understand about web foundations?
3. Prioritize requirements to write a (given) demo working code.
4. Write an extensible code for a given problem.
5. Write a scalable code for a given problem.

Front-End and Javascript UI Developer Interview Questions

Here are some of the most frequently asked front-front end and Javascript related questions asked during a UI developer interview:

1. Explain Hoisting in JavaScript.
2. Explain Closures in JavaScript.
3. Explain Callbacks in JavaScript.
4. Explain async functions in JavaScript.
5. Explain the difference between '==' and '===' in JavaScript.
6. Explain the purpose of constructors in JavaScript.
7. Explain NaN in JavaScript.
8. Explain var, const, let keywords in JavaScript.
9. Explain the difference between 'null' and 'undefined' in JavaScript.
10. Explain the different data types in JavaScript.
11. Explain 'strict mode' in JavaScript.
12. Explain Arrow Functions in JavaScript.
13. Explain Object Destructuring in JavaScript.
14. Explain Spread Syntax or Spread Operator.
15. Explain Rest Syntax or Rest Operator.
16. Explain Higher-order functions in JavaScript.
17. Explain the difference between map() and forEach() in JavaScript.
18. Explain the purpose of the 'this' operator in JavaScript.
19. Explain events in JavaScript.
20. Explain setTimeout and setInterval methods in JavaScript.
21. Explain debouncing and throttling in JavaScript.
22. Explain event bubbling in JavaScript.
23. Explain the different scopes in JavaScript.
24. Explain Scope Chain in JavaScript.
25. When can you have an error that says Undefined Value on the screen?
26. How is the button configuration in the Confirmation box different from the Alert box in JavaScript?
27. On a client machine, how do you detect the server using JavaScript?
28. What, according to you, are the differences between Java and JavaScript?
29. What are timers in JavaScript?
30. What is the use of Void (0)?
31. How can a page be forced to load another page in JavaScript?
32. What is the role of deferred scripts in JavaScript?

More UI Developer Interview Questions for Practice

Below are a set of interview questions that may be asked to UI developer job candidates:

UI Developer HTML Questions

1. Does HTML need a compiler?
2. Explain Semantic HTML.
3. Which is the best HTML debugging tool?
4. How do you use HTML5 New tags in IE8?
5. Explain web accessibility.
6. Explain the difference between <b> and <strong> tag.
7. Explain the difference between <i> and <em> tag.
8. Explain the difference between <article> and <section> tag.
9. Explain Meta Viewport.
10. How do you check for errors in HTML?
11. Is it possible to make the HTML Source Code not viewable?
12. How are active links different from normal links?
13. What happens if the list-style-type property is used on a non-list element like a paragraph?
14. When is it appropriate to use frames?
15. What are the new FORM elements which are available in HTML5?
16. What are the two types of Web Storage in HTML5?
17. Explain some new input types provided by HTML5 for forms.
18. Is <!DOCTYPE html> tag a HTML tag?
19. What is SVG?
20. What is the difference between XHTML, HTML4 and HTML5?

UI Developer AJAX Interview Questions

1. What are the security issues with AJAX?
2. What are the differences between synchronous and asynchronous requests?
3. What is the purpose of XMLHttpRequest?
4. What is the role of a callback function in AJAX?
5. List some tools available for debugging AJAX applications.
6. What is the difference between JavaScript and AJAX?
7. What are the different ready states of a request in AJAX?
8. What are the types of postback in AJAX?
9. Explain JSON in AJAX.
10. How do you test AJAX code?

UI Developer CSS Interview Questions

1. What is the difference between reset.css and normalize CSS?
2. What is the CSS Box Model?
3. How will you check for coding errors in CSS?
4. What is the difference between display none and visibility hidden?
5. How do you center align a div tag in CSS?
6. How do you vertically align a div in CSS?
7. Suggest three ways to reduce the load time of a page.
8. Suggest any three position-property attributes.

UI Developer Angular Interview Questions

1. How do Angular applications work?
2. What are the differences between AngularJS and Angular?
3. What are the advantages of AOT compilations?
4. What is string interpolation in Angular?
5. Explain Promises in Angular.

UI Developer Interview Questions for 6 Years Experience

1. What are floats, and how do they work?
2. Suggest three plugins present in the Bootstrap jQuery plugin library.
3. Which CSS class will you employ to span 16 columns on medium screens and 10 columns on large screens?
4. How will you verify whether a variable is set in PHP or not?
5. What’s the difference between require() and include() in errors?
6. What is a CSS reset?
7. How will you use an AJAX request?
8. How will you use HTML5 new tags in IE8?
9. How will you test website performance?

UI Developer Behavioral Interview Questions

Behavioral interviews are an integral part of the hiring process for UI developers. You can also expect a lot of questions about your past projects in this round. We’ve compiled the different types of behavioral questions to help you prepare for the UI developer interview.

UI Developer Interview Questions on Collaboration and Teamwork

1. What makes good teamwork?
2. How do you feel about working in a team?
3. What makes your teamwork skills different from anyone else’s?
4. Do you prefer teamwork or working independently?
5. What aspects do you think you can change about yourself to become a better team member?
6. How will your previous team describe you as a team member?
7. What kind of personalities do you prefer in your team to work with?
8. How do you deal with a situation where your co-worker is not putting in the level of effort expected from them?
9. What is your preferred style of communication within your team?
10. Tell me about a time you worked well as part of a team.
11. What role have you played in team situations?
12. Have you ever had difficulty working with a manager or other team members?
13. Tell me about a challenging workplace situation that you had to deal with.
14. How would you rate your collaboration skills?
15. What strategies would you use to motivate your team?
16. What would you contribute to our team culture?
17. Tell me about a time you went above and beyond for the team.
18. What would you do if your co-worker took credit for your work?
19. How do you handle a situation when your team is frustrating to work with?

UI Developer Interview Questions on Work-Life Balance

1. What is the best way to maintain a work-life balance?
2. How often do you think employees need vacations? Do vacations help restore harmony to a person’s work-life?
3. Describe a time you were stressed about a project’s outcome and how you coped to achieve the desired result.
4. How do you handle stress and pressure at work, especially amid tight deadlines?
5. Do you indulge in outdoor activities? If yes, how do you think it helps with your work?
6. How important is mental health, according to you? What activities do you do to tend to your mental health actively?

UI Developer Interview Questions on Relationships with Superiors/Managers

1. Describe your boss in one line.
2. According to you, what are the qualities of an ideal boss?
3. What was the biggest criticism you received from your boss? What did you do about it?
4. What if your boss is making a wrong decision regarding a client you know well about? How will you deal with this situation?

UI Developer Interview Questions on Adaptability

1. The culture of this company is quite different from your last organization. How are you planning to get settled?
2. How hungry are you for control? How do you react to situations you have no control over?
3. How will you accommodate sudden, last-minute changes from the client?
4. What strategy will you adopt to implement new technology or processes within your team?
5. How will you deal with resistance from your team on change?
6. What if one of the teammates follows inefficient practices? Have you ever compromised in such situations? What is your take on the same?

UI Developer Interview Questions for 6 Years Experience on Past Projects?

1. What was the most challenging project you have worked on?
2. Have you ever worked on a project and not been able to meet the deadline?
3. What’s the biggest mistake you have made on a project?
4. Have you ever been challenged by your colleagues on a decision you made?
5. Describe an instance when the client was not satisfied with the project’s result.
6. What has been your most successful project so far?
7. Tell me about the last project that you worked on.
8. Have you ever worked on a project and not been able to meet the budget?
9. Tell us about an instance when you had to convince someone to achieve a goal.
10. What, according to you, is one of the biggest mistakes you made in your past projects? How did it change your approach towards work?

UI Developer Interview FAQs

Q1. How do I prepare for my UI developer interview?
A. UI developer interviews vary across levels in the company and regions, so you should start by visiting the career or job openings page on their website and understand the role requirements. You could also sign up for a technical interview preparation course where experts will guide you through the technical interview process at FAANG companies.

Q2. What is the career scope of a UI developer?

‍‍‍A. A UI developer can gain some experience to become an IT project manager. If you are a UI developer with experience and want to move to a management role, you need to develop skills such as relationship building, working in a team, communication, and motivating and influencing others.

Q.3 What is the average salary of a senior UI developer in the U.S.?
A. On average, a UI Developer in the US earns around $119,224 (ranging between $106,922 and $130,083).

Q4. What are the 4 Cs of UI design?

A. The 4 Cs of UI design is given as: 

• Consistency
• Context
• Continuity
• Complementary 

Q5. What is the difference between a UI designer and a UI developer?

A. UI designers focus on the application's visual elements, while UI developers take care of the application's general operation and performance. 

UI developers are in charge of the programming and coding processes that go into creating an application, particularly in relation to how the end user interacts with the software. 

UI designers are responsible for using their knowledge of the program's operation to produce an aesthetic experience that is as compatible as possible with the application's functionalities.

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