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Top 25 Bootstrap Interview Questions and Answers [For Freshers & Experienced]

If you are a mobile web developer, you’ve probably already heard of Bootstrap and its significance in building a fast, responsive and aesthetically designed UI. It is the priority of every business today to deliver an intuitive and flexible user interface and user experience (UI/UX). And Bootstrap helps you do just that! 

Since businesses are keen on developing an adjustable front-end design for devices of varied screen sizes, being skilled at Bootstrap today is worth a huge paycheck. 

So, if you are starting a technical career or are eyeing a higher-up position, here are some of the most commonly asked Bootstrap interview questions and answers to help you land that dream job. So, without further ado, let’s get started! 

Top 25 Bootstrap Interview Questions and Answers

Question 1: What is Bootstrap?

Bootstrap is a highly responsive and easy-to-use front-end framework used to create web applications with HTML, CSS, and JS. It has a quick and intuitive layout for the benefit of its users. Bootstrap allows users to build crisp and aesthetic user interfaces for mobile applications using existing design templates. Its features include Dropdown menus, Buttons, Forms, Glyphicons and Alerts Tab, to name a few.

Question 2: What are the Key Components of Bootstrap?

Bootstrap is loaded with a number of components that make way for an excellent user experience. These include interactive features like pop-ups, dropdown menus, navigation bars, buttons, forms, alerts, etc.

Following are the key components of Bootstrap:

  1. JS Plugins: this is where JS and jQuery plugins are
  2. Customize: used to customize frameworks
  3. CSS: includes CSS files
  4. Scaffolding: contains a grid system, background styles, etc

Question 3: What Makes Bootstrap an Effective Option for Mobile and Web Development?

Bootstrap’s quick and easy to use layout allows for faster development of mobile and web applications. The design templates included are highly responsive and automatically adjust themselves to different screen sizes without any compromise to the essence of a webpage.

Question 4: What are the Various Features of Bootstrap?

Following are some features of Bootstrap:

– It is a free, open-source platform; allows developers to contribute to its improvement. 

– Bootstrap is fast, responsive and extremely easy to use

– It is compatible to use with all browsers

– Bootstrap has a rich library of designs and templates to choose from

Question 5: What are Glyphicons?

Glyphicons in Bootstrap are font-formatted icons that are used to denote actions like a warning, delete, zoom, edit, etc. There are about 200 such icons contained in an individual class. 

The syntax to use these glyphicons is:  

<p><span class = “glyphicons glyphicon-pencil”></span></p>

Question 6: Explain Dropdowns and Button Groups in Bootstrap. 

A dropdown is a dynamic toggle menu that contains a list of linked items under it. It is one of the cleanest design elements of a website. 

The syntax to use these Dropdowns is:

<div class= “dropdown”><!– have your list in this with the class .dropdown-menu –></div>

Button Groups are a series of buttons placed in an adjacent manner. This Bootstrap component requires that division elements with .btn-group class be defined first. After that, the button elements are nested using.btn class.

The syntax is as follows:

<div class=“btn-group”><button class= “btn”>Correct</button></div>

<div class=“btn-group”><button class= “btn”>Wrong</button></div>

Using the above two components, you can create a new component called the Button Dropdown that would enable you to trigger a dropdown using a button element. 

Syntax:

<button class = “btn-default dropdown-toggle”><!— the dropdown component goes here –></button>

Question 7: What are Input Groups? 

Input groups is an extension to the form-control class that allows you to add a text string or include buttons on one of the sides of an input field. 

The .input-group class and .input-group-addon class are used together to implement an Input Group. 

Syntax: 

<div class=”input-group”>

<span class=”input-group-addon” id=”basic-addon1″>@</span>

<input type=”text” class=”form-control” placeholder=”Username” aria-describedby=”basic-addon1″>

</div>

Question 8: What are the Four Contextual Classes to Use with Bootstrap’s Progressive Bar.

Following are the four contextual classes that are used with Bootstrap’s progressive bar:

  1. Progress-success
  2. Progress-info
  3. Progress-warning
  4. Progress-danger

Question 9: How Many Different Button Styles are there in Bootstrap? What are They?

There are 7 different styles in which the Bootstrap button can be used. They are as follows: 

  1. .btn-info
  2. .btn-warning
  3. .btn-danger
  4. .btn-success
  5. .btn-link
  6. .btn-primary
  7. .btn-default

Question 10: Explain Bootstrap Alerts.

Bootstrap alerts are used in the creation of presuming alert messages. This is done mainly to style the messages so they can appear more noticeable to a user.

Following are the four classes in alerts:

  1. .alert-success
  2. .alert-info
  3. .alert-warning
  4. .alert-danger.

Question 11: How do you Create a Vertical or Basic Form in Bootstrap?

Following are the steps to create a vertical basic form in Bootstrap: 

Step 1: To the parent <form> element, add a role form.

Step 2: Add labels and controls inside a <div> with class.form-group

Step 3: Add the .form-control class to every text URL <input>, all <textarea> as well as  <select> elements. 

Question 12: What is Pagination in Bootstrap?

As the label suggests, Pagination allows you to split the contents of your website into different pages to ease navigation. 

Syntax: 

<ul class = “pagination”><!—List elements goes here –></ul>

Question 13: What is a Bootstrap Container?

The bootstrap container is essentially a container to add an HTML code. This container site then becomes a part of the page where the content can be added. This makes your UI faster and more responsive. 

Also Read Bootstrap vs Material UI

Question 14: List Any Three Components of Bootstrap. 

  1. Navbar: acts like a header for navigation on your website

Syntax: <nav class = “navbar”><!—Code your navigation DOM elements –></nav>

  1. Jumbotron: behaves like a viewport; can assume full screen to concentrate on a key content

Syntax: <div class = “jumbotron”><!—Write your content within DOM elements here –></div>

  1. Progress bars: displays feedback highlighting the progress of an action

Syntax: <div class=”progress-bar” role=”progressbar” aria-valuenow=”60″ aria-valuemin=”0″ aria-valuemax=”100″ style=”width: 60%;”>

Question 15: What are the Two Types of Layouts in Bootstrap?

  1. Fluid Layout
  2. Fixed Layout

Question 16: What is Fluid Layout? 

Fluid Layout is a useful feature when the total width of the screen needs to be used in the design. When you choose this option, the layout adjusts itself as per the browser size.

Question 17: What is the Fixed Layout? 

A Fixed Layout is different from the Fluid Layout such that it doesn’t adjust itself as per the size of the browser. However, it is still fast and responsive at 940px. 

Question 18: What is the Modal Plugin in Bootstrap?

An inherited window placed as a layer over the parent window is known as the Modal window. This window adds value to the user experience by making it functional. The plugin used to create Modal windows is called the modal plugin.

Question 19: What are the Bootstrap Collapsing Elements?

You can collapse any Bootstrap element without JavaScript code. This can be done by adding data-toggle= ”collapse” to the controller element. The data-target is also included to give it control to collapse the element. 

To use this Bootstrap feature, use .collapse(options).

Question 20: Define a Bootstrap Well?

Bootstrap well is similar to the Bootstrap container and helps the content look more suppressed and clean on the page. It can also be used to wrap the content by adding .well class.

Question 21: What is the Carousel Plugin in Bootstrap.

The Carousel Plugin allows you to create sliders on your web pages. Sliders allow large blocks of contents to be recessed to a small space on the page. 

A few carousel plugins you can use are: 

.carousel(options)

.carousel(‘pause’)

.carousel(cycle’) 

.carousel(‘prev’)

.carousel(‘next’)

Question 22: Explain the Output of the Following Code.

<div class=”progress”>

<div class=”progress-bar progress-bar-success” style=”width: 65%”>

<span class=”sr-only”>75% successfully completed</span>

</div>

<div class=”progress-bar progress-bar-warning” style=”width: 20%”>

<span class=”sr-only”>30% completed with warnings</span>

</div>

<div class=”progress-bar progress-bar-danger” style=”width: 15%”>

<span class=”sr-only”>15% did not complete</span>

</div>

</div>

Answer: The output of the above code would show a full width and fully populated result on the progress bar. This is because Bootstrap piles multiple bars into a single bar when placed in the same progress parent element. Also, the total progress bar sum is 100%. 

Question 23: State the Codes used for Code Display in Bootstrap?

Answer: There are two codes used for code display. They are:

  1. <code> tag 
  2. <pre> tag

Question 24: Explain Normalize in Bootstrap. 

Bootstrap normalize is a feature on Bootstrap using which a small CSS file is employed to increase cross-browser consistency.

Question 25: What is the Method to Customize Links of Pagination in Bootstrap?

Use .disabled for links that are not clickable and use .active for referencing the current page.

Checkout: Bootstrap vs Material UI

Conclusion 

We hope these questions and answers helped you brush up on your knowledge of Bootstrap. Good luck with that interview!

If you’re interested to learn more about full-stack software development, check out upGrad & IIIT-B’s PG Diploma in Full-stack Software Development which is designed for working professionals and offers 500+ hours of rigorous training, 9+ projects and assignments, IIIT-B Alumni status, practical hands-on capstone projects & job assistance with top firms.

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