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31+ Bootstrap Interview Questions And Answers

Bootstrap is a popular open-source front-end toolkit used for creating responsive, mobile-first websites. It includes pre-designed HTML and CSS templates for various UI components such as buttons, forms, modals, and more. Bootstrap helps developers quickly build and customize web applications with ease, ensuring consistency across different devices. Below are essential interview questions for both beginners and advanced users of Bootstrap.


Most asked Bootstrap interview questions



What is Bootstrap and why is it used?

Bootstrap is a free and open-source framework for developing responsive and mobile-first websites. It includes HTML, CSS, and JavaScript-based design templates for UI components, enabling easier and faster development.


How do you include Bootstrap in a project?

Bootstrap can be included in a project by linking to its CDN in the HTML section or by downloading and hosting the Bootstrap files locally.


What are the advantages of using Bootstrap?

The advantages of using Bootstrap include responsive design, consistent UI components, cross-browser compatibility, and faster development time. It also has abundant documentation and community support.


Explain the grid system in Bootstrap.

The grid system in Bootstrap is based on a 12-column layout. It uses a series of containers, rows, and columns to layout and align content. Columns can span multiple rows and be nested. Classes like .col-*, .col-sm-*, and .col-md-* help define how columns should behave on different devices.


How do you create a button using Bootstrap?

<button type='button' class='btn btn-primary'>Click Me</button>

You can create a button using Bootstrap by using the btn and btn-primary classes.

<button type='button' class='btn btn-primary'>Click Me</button>


What are Bootstrap's responsive breakpoints?

Bootstrap's responsive breakpoints include xs (extra small), sm (small), md (medium), lg (large), and xl (extra large). These breakpoints help design responsive layouts for different screen sizes.


What is the use of the .container class in Bootstrap?

The .container class creates a responsive fixed-width container for your content. The width of the container varies based on the screen size due to its responsive behavior.


How can you center a div using Bootstrap?

You can center a div using Bootstrap classes like .d-flex, .justify-content-center, and .align-items-center.

<div class='d-flex justify-content-center align-items-center'>Centered Content</div>


What is the purpose of Bootstrap's navbar component?

The navbar component in Bootstrap provides a responsive and customizable navigation bar, essential for guiding users through the website. It includes support for branding, navigation links, and forms.


How do you create a form using Bootstrap?

You can create a form using Bootstrap by using classes like .form-group, .form-control, and .btn.

<form><div class='form-group'><label for='email'>Email:</label><input type='email' class='form-control' id='email'></div><button type='submit' class='btn btn-primary'>Submit</button></form>


What are 'cards' in Bootstrap?

Cards in Bootstrap are flexible and extensible content containers that include options for headers, footers, content, and various styles with the .card class.


How do you add an image carousel in Bootstrap?

You can add an image carousel in Bootstrap using the .carousel, .carousel-inner, .carousel-item, and additional control classes.

<div id='carouselExample' class='carousel slide' data-ride='carousel'><div class='carousel-inner'><div class='carousel-item active'><img src='img1.jpg' class='d-block w-100'></div><div class='carousel-item'><img src='img2.jpg' class='d-block w-100'></div></div><a class='carousel-control-prev' href='#carouselExample' role='button' data-slide='prev'><span class='carousel-control-prev-icon' aria-hidden='true'></span></a><a class='carousel-control-next' href='#carouselExample' role='button' data-slide='next'><span class='carousel-control-next-icon' aria-hidden='true'></span></a></div>


How can you make a table responsive using Bootstrap?

To make a table responsive, wrap it with the .table-responsive class.

<div class='table-responsive'><table class='table'><!-- table content --></table></div>


What are glyphicons and how are they used in Bootstrap?

Glyphicons are a set of icon fonts that were used in Bootstrap 3 for adding icons to buttons, labels, and more. In Bootstrap 4 and later, use Font Awesome or other icon libraries instead.


How do you add a modal in Bootstrap?

A modal in Bootstrap can be added using the .modal and related classes. Programmatic control can be managed with jQuery.

<button type='button' class='btn btn-primary' data-toggle='modal' data-target='#myModal'>Open Modal</button><div class='modal fade' id='myModal' tabindex='-1' role='dialog'><div class='modal-dialog' role='document'><div class='modal-content'><div class='modal-header'><h5 class='modal-title'>Modal Title</h5><button type='button' class='close' data-dismiss='modal'><span>&times;</span></button></div><div class='modal-body'>Modal Body</div><div class='modal-footer'><button type='button' class='btn btn-secondary' data-dismiss='modal'>Close</button><button type='button' class='btn btn-primary'>Save changes</button></div></div></div></div>

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How do you customize the default Bootstrap styles?

You can customize Bootstrap styles by overriding the default CSS rules with your own styles or by using Bootstrap’s SASS variables and mixins to modify the behavior and appearance.


Explain the use of the .sr-only class in Bootstrap.

The .sr-only class is used to hide an element visually but keep it accessible to screen readers. This is useful for improving accessibility without affecting the visual layout of a page.


How can you implement a custom theme in Bootstrap?

To implement a custom theme in Bootstrap, you can customize the SASS variables or add custom CSS on top of Bootstrap. You can also use the Bootstrap Theme Template as a starting point for your theme.


What does the following Bootstrap code do?

<div class='container-fluid'><div class='row'><div class='col-md-8'>Content 1</div><div class='col-md-4'>Content 2</div></div></div>

This code creates a fluid container with two columns. The first column (Content 1) spans 8 out of 12 columns on medium and larger devices, while the second column (Content 2) spans 4 out of 12 columns.


How do you use Bootstrap’s utility classes for spacing?

Bootstrap’s utility classes for spacing include classes like .m-* for margin and .p-* for padding. You can specify the sides (top, right, bottom, and left) and set the spacing value using these classes.


How can you create a responsive navbar that collapses on smaller screens?

To create a responsive navbar that collapses on smaller screens, use the .navbar-collapse and .navbar-toggler classes.

<nav class='navbar navbar-expand-md navbar-light bg-light'><a class='navbar-brand' href='#'>Brand</a><button class='navbar-toggler' type='button' data-toggle='collapse' data-target='#navbarNav'><span class='navbar-toggler-icon'></span></button><div class='collapse navbar-collapse' id='navbarNav'><ul class='navbar-nav'><li class='nav-item'><a class='nav-link' href='#'>Link 1</a></li><li class='nav-item'><a class='nav-link' href='#'>Link 2</a></li></ul></div></nav>


How can you make a sticky footer using Bootstrap?

To create a sticky footer using Bootstrap, use the following code:

.footer { position: fixed; bottom: 0; width: 100%; height: 60px; line-height: 60px; background-color: #f5f5f5; }


How do you use Bootstrap's flex utilities?

Bootstrap's flex utilities allow you to control the layout of elements using flexbox. You can use classes like .d-flex, .flex-column, .justify-content-between, and .align-items-center to align and position flex items.


What are Bootstrap's classes for responsive visibility?

Bootstrap's visibility classes include .d-*-none and .d-*-block for hiding or showing elements based on screen size. For example, .d-md-none will hide the element on medium and larger screens.


Explain how to use Bootstrap’s card decks.

A card deck enables a group of cards to be displayed in a grid layout, with each card having equal width and height. Use the .card-deck class to create a card deck.


How do you reorder columns in Bootstrap?

To reorder columns in Bootstrap, use the .order-* classes. For example, you can use .order-md-1 to place a column first on medium devices.

<div class='container'><div class='row'><div class='col-md-4 order-md-2'>Column 1</div><div class='col-md-4 order-md-1'>Column 2</div></div></div>


How can you add a tooltip in Bootstrap?

You can add a tooltip in Bootstrap by using the data-toggle='tooltip' attribute and initializing tooltips with JavaScript.

<button type='button' class='btn btn-secondary' data-toggle='tooltip' title='Tooltip text'>Hover me</button><script>$(function () { $('[data-toggle='tooltip']').tooltip() })</script>


Describe the process of nesting a grid in Bootstrap.

Nesting a grid involves placing a .row and .col-* inside an existing column. This allows for more complex layouts within a column.

<div class='container'><div class='row'><div class='col-6'>Col 1<div class='row'><div class='col'>Nested Col</div></div></div></div></div>


How do you use Bootstrap’s mix-ins?

Bootstrap's mix-ins are reusable pieces of CSS that can be included in other styles using SASS @include rules. They provide a way to avoid code repetition.


What are Bootstrap’s utility classes for text alignment?

Bootstrap provides utility classes for text alignment such as .text-left, .text-center, and .text-right to quickly align text within elements.


How can you enable responsive embed for videos in Bootstrap?

To create a responsive embed for videos, use the .embed-responsive class combined with appropriate aspect ratio classes like .embed-responsive-16by9.


Bootstrap Interview Tips

Understand the Question First

  • Before you begin to answer a question, ensure you fully understand what is being asked. This not only saves time but also helps in providing a relevant and concise answer. If the question is unclear, don’t hesitate to ask the interviewer for more details.

Stay Calm and Think Aloud

  • Tough interview questions can be intimidating, but it's important to stay calm. Think aloud to let the interviewer understand your thought process. This approach demonstrates your problem-solving skills and often leads to a more constructive conversation.

Relate to Your Past Experience

  • When answering a tough question, try to relate it to your past experience. Providing real-world examples from your previous work can make your answer more powerful and credible. Employers appreciate when candidates can draw from past situations to address new challenges.

It’s Okay to Admit What You Don’t Know

  • If you don’t know the answer to a tough question, it’s better to admit it rather than guessing. Employers value honesty and the willingness to learn. You can follow up by explaining how you would find the answer or handle the situation if it arose in real life.

Practice Common and Tough Questions

  • Preparation is key to handling tough interview questions. Practice common and challenging questions before your interview. The more familiar you are with different types of questions, the better you will perform under pressure. Mock interviews can also help you get accustomed to the interview format and improve your confidence.


What is the salary of Bootstrap developer?

The salary of a Bootstrap developer can vary based on experience, location, and specific project requirements. On average, a Bootstrap developer earns between $70,000 to $120,000 per year in the United States. Rates can also be calculated hourly, typically starting from $45 per hour. Read more

What does a Bootstrap developer do?

A Bootstrap developer specializes in creating responsive, mobile-first front-end web applications using the Bootstrap framework. Their duties include designing and implementing user interfaces, ensuring cross-browser compatibility, and optimizing web pages for performance and user experience. Read more

How do I become a Bootstrap developer?

To become a Bootstrap developer, you should start by learning the fundamentals of HTML, CSS, and JavaScript. Familiarize yourself with the Bootstrap framework and practice building responsive web applications. Building a portfolio showcasing your projects can help demonstrate your skills to potential employers. Read more

Why using FireHire for hiring Bootstrap developers is the best choice?

FireHire stands out in the world of hiring services due to our efficient, risk-free hiring process. With a vast network of over 1600 talents, we connect you with pre-vetted senior Bootstrap developers quickly, typically within 5 days. Our 30-day risk-free replacement guarantee ensures you are completely satisfied with our service, giving you peace of mind.

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