10 Best Front-end Development Q&A for Coding Interview

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Learn about the 10 best front-end development Q&A with code examples.

Topics covered include the box model in CSS, inline vs block elements, vertical centering in CSS, event delegation in JavaScript, benefits of using a CSS preprocessor like Sass, website performance optimization techniques, cookies vs sessionStorage vs localStorage, the purpose of a CSS framework, and how to make a website responsive using CSS media queries.

Front-end Development Q&A

Grokking the Coding Interview: Patterns for Coding Questions
Grokking the Coding Interview: Patterns for Coding Questions

Prepare for your next coding interview with these front-end development concepts.

Introduction to Front-end Development Q&A

Front-end development is a crucial aspect of web development, and as a front-end developer, it is essential to be well-prepared for coding interviews.

To help you ace your next coding interview, we have compiled a list of the 10 best front-end development questions along with their answers and code examples.

These questions cover a range of topics, from HTML and CSS to JavaScript and frameworks. Let’s dive in to Front-end Development Q&A.

1. What is the box model in CSS?

The box model in CSS describes the layout of elements on a webpage. It consists of four components: content, padding, border, and margin.

The content refers to the actual content of the element, while padding adds space between the content and the border.

The border is a line that surrounds the element, and the margin creates space between the element and other elements on the page.

Code Example:

div {
  width: 200px;
  height: 100px;
  padding: 20px;
  border: 1px solid black;
  margin: 10px;

2. What is the difference between inline and block elements?

Inline elements do not start on a new line and only take up as much width as necessary.

They include elements like <span> and <a>. On the other hand, block elements start on a new line and take up the full width available. Examples of block elements are <div> and <p>.

Grokking the Coding Interview: Patterns for Coding Questions
Grokking the Coding Interview: Patterns for Coding Questions

3. How can you vertically center an element in CSS?

To vertically center an element in CSS, you can use the following code:

.container {
  display: flex;
  align-items: center;
  justify-content: center;

This code uses the flexbox layout to align the content vertically and horizontally within the container element.

4. What is event delegation in JavaScript?

Event delegation is a technique in JavaScript where you attach an event listener to a parent element instead of individual child elements.

This allows you to handle events on dynamically added elements or elements that may not exist when the page loads.

The event is then propagated from the child element to the parent element.

5. What is the difference between == and === in JavaScript?

In JavaScript, == is used for loose equality comparison, while === is used for strict equality comparison.

Loose equality comparison only checks for equality of values, while strict equality comparison checks for both value and type.

Code Example:

console.log(1 == '1'); // true
console.log(1 === '1'); // false

6. What are the benefits of using a CSS preprocessor like Sass?

A CSS preprocessor like Sass provides several benefits, including:

  • Variables: Sass allows you to define variables for reusable values.
  • Nesting: Sass allows you to nest CSS rules, making the code more readable and maintainable.
  • Mixins: Sass allows you to define reusable styles and apply them to multiple elements.
  • Importing: Sass allows you to split your CSS code into multiple files and import them as needed.

7. How can you optimize website performance?

To optimize website performance, you can implement the following techniques:

  • Minify and compress CSS and JavaScript files.
  • Optimize images by reducing their size and using appropriate formats.
  • Enable browser caching to reduce server requests.
  • Use a content delivery network (CDN) to serve static files.
  • Reduce the number of HTTP requests by combining files and using CSS sprites.
Grokking the Coding Interview: Patterns for Coding Questions
Grokking the Coding Interview: Patterns for Coding Questions

8. What is the difference between cookies, sessionStorage, and localStorage?

Cookies, sessionStorage, and localStorage are used to store data on the client-side, but they have some differences:

  • Cookies: Cookies are small text files that are stored on the client’s computer. They have an expiration date and are sent to the server with every request.
  • sessionStorage: sessionStorage stores data for a single session and is cleared when the browser is closed.
  • localStorage: localStorage stores data without an expiration date and remains stored even after the browser is closed.

9. What is the purpose of a CSS framework?

A CSS framework provides a set of pre-written CSS styles and components that can be used to quickly build websites.

It helps in maintaining consistency, responsiveness, and cross-browser compatibility. Popular CSS frameworks include Bootstrap and Foundation.

10. How can you make a website responsive?

To make a website responsive, you can use CSS media queries to apply different styles based on the screen size.

This allows the website to adapt and display properly on various devices, such as smartphones, tablets, and desktops.

Code Example:

@media screen and (max-width: 768px) {
  /* Styles for smaller screens */


Being well-prepared for front-end development Q&A is crucial for acing your coding interviews.

Grokking the Coding Interview: Patterns for Coding Questions
Grokking the Coding Interview: Patterns for Coding Questions

By familiarizing yourself with these 10 best front-end development questions and their answers, along with the provided code examples, you will be better equipped to showcase your skills and knowledge. Remember to practice implementing these concepts in your own projects to reinforce your understanding. Good luck with your next coding interview!








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