UI Developer Interview Questions

ui developer interview questions

Are you looking for a career in UI development? Well, then the future is yours. UI developers are the third most in-demand professionals today in the IT industry.

In this blog, we have collected the frequently asked Top 20 UI Developer Interview Questions and answers to help you get acquainted with the nature of questions you may encounter in your next UI developer interview.

Frequently Asked UI Developer Interview Questions [Updated 2020]

  • What is Semantic HTML, and why use it?
  • How static, relative, absolute, fixed, sticky, initial, and inherit position will differ?
  • How block, inline, and inline-block are different?
  • Explain web accessibility.
  • What are bold and strong tags used for?
  • What is JavaScript Hoisting?
  • What is HTML?
  • What is a responsive website?
  • what is event bubbling and event capturing?
  • What’s the difference between HTML and XHTML?
  • What is an AJAX request?

Whether you’re a beginner or experienced, this Best UI developer interview questions will definitely be helpful to take your career to the next level in 2020.

Let’s get started.

UI Developer Interview Questions and Answers

Q1) What is Semantic HTML, and why use it?

Ans. Semantic HTML is also known as semantic markup. It is the right use of HTML to reinforce the content meaning on a web page, rather than just defining its appearance. In simple words, it introduces a definition to the context rather than presentation.
By using HTML tags that have more meaning, you will be creating pages that have more necessary data than those that simply enclose around with <div> tags.

Q2) How static, relative, absolute, fixed, sticky, initial, and inherit position will differ?

Ans. There are several types of positioning. Let’s see what all of these types indicate.
Static – This one is a default value. In this, all the elements render in order, as they appear in the document.

  • Absolute: in this, the element positioned relative to its ancestor element.
  • Relative – In this, the element is positioned relative to its normal position.
  • Fixed – In this, the element is positioned relative to the browser window.
  • Sticky – In this, the element is positioned based on the user’s scroll position.
  • Initial – It sets a property to its default value.
  • Inherit – It inherits property from its parent element.

Q3) How block, inline, and inline-block are different?

Block: It always starts on a new line and loads up horizontal space left and right on the web page. We can add margins and paddings on top, right, left, and bottom sides of the block element.

Inline: It won’t start on a new line and available on the same line as the content and tags beside them. We can add margins and padding only on the left and right on an inline element.

Examples: <strong>, <img> tags.

Inline-block: They are just similar to inline elements, and have margins and padding on all four sides.

Q4) Explain web accessibility.

Ans. Web accessibility is referred to as providing website access for differently-abled and disabled persons so that they can easily use the web, navigate, understand and interact with the web.

Q5) What are bold and strong tags used for?

Ans. Bold and strong tags are elements of HTML tags. They are specifically used for highlighting relevant sections or words on a web page. The bold tag stands for bold and strong tag stands for highlighted.

Q6) What is JavaScript Hoisting?

Ans. Hoisting is a JavaScript mechanism, where assigned functions and variable declarations are moved or hoisted to the top of their scope before code execution. This clearly means that no matter where functions and variables are declared, they will be transferred to the top of their scope despite whether their scope is local or global.

Q7) What is HTML??

Ans. HyperText Markup Language is one of the most popular languages used for creating websites, along with elements viewed on a web browser.

Q8) What is a responsive website?

Ans. A responsive website has been designed to adapt or respond, based on types of computing devices and technology used by visitors for displaying the site. Any website is meant to be responsive when it looks good at any size and fits in all types of screen resolution device types.

Q9) What is event bubbling and event capturing?

Event bubbling and event capturing are the two most important terms in JavaScript. Event flow represents the order in which event is received on the web page.
Event bubbling is when the event starts from the target element to its parent, then all its ancestors on the way from the bottom to top. Currently, all modern browsers support event bubbling as the default way of event flow.
The event which starts from the top element to the target element is called event capturing. Modern browsers won’t support event capturing, we can achieve it using Javascript.

Q10) What’s the difference between HTML and XHTML?

Ans. HTML and XHTML languages are used for creating web pages, while HTML stands for hypertext markup language and XHTML stands for extensible hypertext markup language. XHTML is XML based. The HTML is SGML based and compared to HTML, it is strict and doesn’t allow users to get away with any structure lapses or coding.

Q11) What’s the differences between a document and a Window?

A window is a primary thing that gets loaded into the browser. Window object includes all the major properties like innerWidth, length, name, innerHeight, and more.
The document object is your HTML, ASPX, PHP, or another document that will be loaded into the browser. The document gets loaded inside the Window object and has the properties available to it like URL, title, etc.

Q12) Why is no compiler required for HTML?

Ans. The compilation is needed when to convert code to assembly level and then machine level. As HTML is a front end language, it doesn’t need a compiler.

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Q13) List the plugins available in the Bootstrap jQuery plugin library.


  • Affix
  • Button
  • Alert
  • Popover
  • Tooltip
  • Modal
  • Carousel
  • Collapse
  • Dropdown
  • Scrollspy
  • Tab

Q14) What is an AJAX request?

Ans. AJAX is a technique for creating dynamic and fast web pages, allowing webpages to get updated synchronously by exchanging small amounts of data. It is used to post or get data from a remote server without any need to reload the page.

Q15) How is normalize.css different from Reset.css?

Ans. Normalize.css is a small CSS file used for providing a better cross-browser consistency in the default styling of HTML elements. It’s a modern, HTML5-ready, alternative to the traditional CSS reset.
Reset.css (or “CSS Reset”) eliminates all browser default styles, such as padding, border, and margin. It resets the styling of all HTML elements to a consistent baseline.

Q16) How do you check whether a variable is set or not in PHP?

Ans. Using this command – isset($var)

Q17) How does float work?

Ans. Float is used to push the element to left or right. The float property can have one of four values such as inherited, none, left, and right.

Q18) How local storage, session storage, and cookies differ from each other?

Local storage: It allows maximum data storage limit with no expiration date.
Session storage: It stores the data associated with a session and data disappears when the user closes the browser or tab.
Cookies: For this, the data size should be less than 4KB. They are stored mostly for server-side reading.

Q19) What’s the difference between a UI developer and a front-end developer?

Front-end developer creates websites using HTML, JavaScript, CSS, client-side technologies, making sure all functions of the website work properly. UI developers similarly use the HTML, client-side technologies, etc. and makes the site user friendly.

Q20) What’s the difference between require and include?

Ans. The difference between require and include arises when you encounter an error: require will emit a fatal error (E_COMPILE_ERROR) and halt the script, whereas include will emit a warning (E_WARNING) and the script will continue.

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