Bootstrap Interview Questions And Answers

Bootstrap is a flexible and versatile toolkit with CSS, HTML, and JavaScript tools. These tools come in handy when developing and creating web applications and pages. It is an open-source and free project built by and for Twitter, and people can find the hosting on GitHub.

When Jacob Thornton and Mark Otto were working at Twitter, they announced and created Bootstrap in August 2011. The primary goal of the project is to simplify interface creation and maintenance. This platform was exactly the way to make several popular design patterns along with online designing and development. It is more than just a framework. The project was initially popular as the Twitter Blueprint but later got a name Bootstrap. It was released as an open-source platform. The folks are still maintaining the platform, along with a helping hand from the GitHub contributors.

Bootstrap has gained significant popularity since 2011 as it is an open-source release. Web developers and designers highly prefer Bootstrap since it is versatile and is easy to use. The primary benefits of the platform are that it is responsive by design and supports a wide range of browsers. It also delivers a consistent design by employing reusable components. The primary benefit is that it is very simple to use and understand. Bootstrap comes with integrated jQuery plugins and a programmatic JavaScript API for rich extensibility, which you can attain through JavaScript. Any editor or IDE, as well as server-side technology and language, can work with this platform.

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Bootstrap works for the development of mobile application development as it comes with several responsive features and design templates that are easy to get familiarize with. In other words, if you want to become an app developer, it is best to turn to Bootstrap since it is the first mobile-approach platform.

Thanks to advancements in digital marketing or website development, companies are now looking for ways that can help them reach their customers more quicker than ever. Usually, enterprises hire high-end developers to build responsive and result-driven websites that can target customers through all platforms, such as mobile and desktop users. To hire the best developers, companies are asking several advanced to basic Bootstrap interview questions and answers to find the best talent amongst the masses.

You should prepare these because when it comes to web development jobs, employers are most likely to add some bootstrap questions. Another thing to remember is that when asking these questions, employers start with basic and easy questions and gradually increase the difficulty of the questions as you progress with your answers.

1 . What is Bootstrap?

Bootstrap is a platform for web development based on a front-end framework. It is used to create exceptional responsive designs using HTML, and CSS. These templates are used for forms, tables, buttons, typography, models, tables, navigation, carousels and images. Bootstrap also has Javascript plugins, which are optional. Bootstrap is mostly preferred for developing mobile web applications.

2 . Explain why Bootstrap is preferred for website development.

Bootstrap has better features as compared to other web development platforms. It provides extensive browser support for almost every known browser such as Opera, Chrome, Firefox, Safari, etc. If you are well-acquainted with CSS and HTML, web development becomes easy on Bootstrap.

Also, it supports mobile applications with the help of responsive design and can adjust CSS as per the device, screen size, etc. Instead of creating multiple files, it creates only a single file reducing the work of a developer.

3 . What are the key components?

The key components of Bootstrap include:

  • CSS: It consists of  various CSS files
  • Scaffolding: It provides a basic structure with the Grid system, link styles, and background
  • Layout Components: This gives the list of layout components
  • JavaScript Plugins: It contains many jQuery and JavaScript plugins
  • Customise: To get your own version of the framework, you can customise your components

4 . List some features.

Some of the features of Bootstrap are:

  • It provides an open-source for use
  • Bootstrap has Compatibility with all browsers
  • It has Responsive designs
  • Easy to use and fast

5 . What are Class loaders?

A class loader is a part of JRE or Java Runtime Environment which loads Java classes into a Java virtual environment. Class loaders also perform the process of converting a named class into its equivalent binary form.

6 . How many types of layout are available here?

There are two major layouts for Bootstrap:

  1. Fluid Layout- This layout is necessary for creating an app that is 100 % wider and covers all the screen width.
  2. Fixed Layout- It is used only for a standard screen (940px). Both layouts can be used for creating a responsive design.

7 . What is a Bootstrap Grid System?

Bootstrap includes a responsive, mobile-first fluid grid system that appropriately scales up to 12 columns as the device or viewport size increases. It includes predefined classes for easy layout options, as well as powerful mixins for generating more semantic layouts.

8 . Why do we use Jumbotron?

Jumbotron is used for highlighting content in bootstrap. It could either be a slogan or probably a headline. It increases the heading size and gives a margin for the content of the landing page.

9 . What are the two codes used for code display?

There are two simple ways to display code in Bootstrap:

  • <code> tag: This tag is used to display an inline code.
  • <pre> tag: If you have a code with several lines or even a block element, you can display it using this.

10 . Explain the typography and links.

Bootstrap sets a basic global display (background), typography, and link styles.

  • Basic Global display − It sets background-colour: #fff; on the <body> element.
  • Typography − This uses the @font-family-base, @font-size-base, and @line-height-base attributes as the typographic base
  • Link styles − It sets the global link colour via attribute @link-colour and applies link underlines only on :hover.

11 . What is a progress bar?

Progress bar is used with HTML tag style in HTML element using <progress> keyword. In bootstrap we use html5 <progress> with CSS classes that have special features in bootstrap, that are only made for the progress bar.

12 . How do you make images responsive?

Bootstrap allows you to make the images responsive by adding a class .img-responsive to the <img> tag. This class applies max-width: 100%; and height: auto; to the image so that it scales nicely to the parent element.

13 . What is the difference between Bootstrap and Foundation?

Bootstrap: 

  • Bootstrap offers an unlimited number of UI elements
  • Bootstraps uses pixels
  • It encourages to design for both desktop and mobile
  • Bootstrap support LESS as its preprocessor

Foundation: 

  • In Foundation UI element options are very limited in numbers
  • Foundation use REMs
  • Foundation encourages to design mobile first
  • It supports Sass and Compass as its preprocessor

14 . What are Bootstrap collapsing elements?

Bootstrap collapsing elements enable you to collapse any particular element without writing any JavaScript code or the accordion markup. To apply collapsing elements in bootstrap, you need to add data-toggle= “collapse” to the controller element along with a data-target or href to automatically assign control of a collapsible element. Also, you can use .collapse (options), .collapse (‘show’) or .collapse (‘hide’) for the same.

15 . Explain types of lists supported.

Bootstrap supports three types of lists such as:

  1. Ordered lists − An ordered list is a list that falls in some sort of sequential order and is prefaced by numbers.
  2. Unordered lists − An unordered list is a list that doesn’t have any particular order and is traditionally styled with bullets. If you do not want the bullets to appear then you can remove the styling by using the class .list-unstyled.
  3. Definition lists − In this type of list, each list item can consist of both the <dt> and the <dd> elements. <dt> stands for definition term. Subsequently, the <dd> is the definition of the <dt>.

16 . What is the media object in Bootstrap and what are their types?

Media objects in Bootstrap help you to put media objects like image, video or audio to the left or right of the content blocks. Media elements can be created using the class .media and the source is specified in using the class .media-object. Media-objects are of two types.

The two types of media object are:

  • .media
  • .media-list

17 . Explain the layout types?

Here is the list of layouts available in Bootstrap. 

  • Fluid-Layout- Also referred to as .container fluid layout, it can measure the unit of block content along with the images. 
  • Fixed-layout-This layout is also referred to as the .container layout. It facilitates a responsive container with fixed width.

18 . Give an idea about the offset columns?

In Bootstrap, offset is used to push columns over to facilitate more spacing. One has to use the .col-md-offset-* classes to utilise offsets on large displays. You can move columns to the right with the usage of .offset-md-* classes. To be precise, offset in Bootstrap works like a blank column.

19 . Bootstrap for website building – why should you choose?

There are many reasons for choosing bootstrap for website building.

Equipped with a great grid system

To create a good page layout, good grids are of utmost necessity. Bootstrap comprises great mobile grid systems which are responsive too. Grid systems are also a practical choice when you want to hide some content.

Compatibility

Bootstrap is compatible with all leading browsers and IE versions. It comes with HTML5 and CSS 3 which are the future of web designing.

Facilitates documentation

Bootstrap renders impressive documentation and demos which makes the process of web designing quite smooth.

20 . Explain Bootstrap container?

Bootstrap containers play a decisive role in implementing the responsive behaviours of your layout. It sets the margin of the content within a specific page. It comprises row elements and these row elements are column containers. With a Bootstrap container, the developer can pad the content inside the page.

21 . Why is bootstrap vital for mobile web development?

Bootstrap is vital for mobile web development for 3 reasons.

  • It redesigns the elements to employ flat design and also the first approach of mobiles
  • As the layout depends on percentage, it helps in keeping the mobile support in the front position.
  • It offers grid systems to describe layouts. This system consists of 12 columns along with different sizes of various devices like mobiles, tablets, IPad, laptops, and desktops. All these devices have pre-decided sizes that are capable of taking the accountability of responsive components. Thus, you need not use CSS.

22 . Bootstrap navbar – what do you know?

With the help of the Bootstrap navbar, you can design a standard navigation bar. You can also add links inside the navigation bar.

23 . What is normalising?

Normalise in Bootstrap refers to the phenomenon where the browsers can be made to display elements in a consistent manner. It is also referred to as browser reset.

24 . Explain Scrollspy Plugin?

The Bootstrap Scrollspy is a mechanism related to the navigation elements. It can automatically highlight the navigation links which are reliant on the scroll position. This indicates the visitors and which portion of the page they are currently in. It makes the web page more elegant and fast.

25 . Give an idea about bootstrap breadcrumb?

With breadcrumb, you can highlight the current location of the web page within the domain of navigational hierarchy. Breadcrumb automatically adds the separators via the CSS framework.

26 . Explain bootstrap well-properly?

Bootstrap well is a container in < div > that makes the content look sunken. To build it, wrap the content that you want in the well with a < div > having the class of .well. Its size can be changed by optional classes like well-lg in association with .well class. Thus, the padding is affected and the size becomes either small or large according to the class.

27 . Why is the affix Plugin significant in bootstrap?

The affix Plugin allows the element to be locked within a particular area in a page. This Plugin is most commonly used with navigation menus and with social icon buttons. This makes them stick as a particular area when the user is scrolling up and down the page.

28 . Why is the modal Plugin vital?

In the realm of the Bootstrap framework, a modal is a child window. The parent window layers it from above. The main purpose of the modal Plugin is to display content from a different source that can interact without entirely leaving the parent window.

29 . State clearly about Bootstrap carousel Plugin?

If you want to insert a slider into your website, use Bootstrap carousel. This flexible and responsive way lets you add any images, iframes, videos, or any content that you wish.

30 . What is the transition Plugin?

Transition Plugin in Bootstrap is used to facilitate the simple effects of transition. To incorporate this Plugin in an individual manner, you have to use the transition.js with other JS files.

31 . Explain glyphicons in bootstrap?

Glyphicons are icon fonts or pictograms that are suitable for use in web projects. In Bootstrap, they are used as a custom font that has more than 260 glyphs instead of letters. Glyphicons are not free. They need proper licensing. However, the creator has made them accessible free of cost. Glyphicons are commonly used in buttons, toolbars, texts, and buttons.

32 . Input groups in bootstrap – explain?

Bootstrap input groups resemble a container that can be used to improve an input by giving buttons, icons, or texts. The .input-group-add on class ascribes an image or assistance text succeeding to the input field.

33 . Explain what pagination in bootstrap and how they are classified?

Pagination is the handling of an unordered list by bootstrap. To handle pagination it provides following classes

  • .pagination: To get pagination on your page you have to add this class
  • .disabled, .active: Customise links by .disabled for unclickable links and .active to indicate the current page
  • .pagination-Ig, .pagination-sm: Use these classes to get different size item

34 . Explain what are the steps for creating basic or vertical forms?

The steps for creating basic or vertical forms are

  • Add a role form to the parent <form> element
  • Wrap labels and controls in a <div> with class .form-group. To achieve optimum spacing this is needed
  • Add a class of .form-control to all texturl <input> , <textarea> , and <select> elements

35 . How can you add a badge to a list group?

To add a badge to the list group in Bootstrap you have to simply add <span class = “badge”> within the <li> element.

36 . How can you make an image round in Bootstrap 4?

You can use the .rounded class to make an image round.

37 . Name the contextual classes that are used with the progress bar.

The contextual classes used with the progress bar are as follows:

  • The .bg-primary class
  • The .bg-secondary class
  • The .bg-success class
  • The .bg-danger class
  • The .bg-warning class
  • The .bg-info class
  • The .bg-white class
  • The .bg-light class
  • The .bg-dark class

38 . What are responsive utility classes?

Responsive utility classes in Bootstrap are a set of classes that are used to conceal or exhibit the HTML elements based on screen resolution that discerns by media query . For Example: “hidden-md-down”

39 . What are the different button styles?

In Bootstrap, there are lots of styles that we can use with the buttons.

Some of them are:

  • Buttons with colors
  • Buttons with a colored outline
  • Small buttons
  • Large buttons
  • Block-level buttons
  • Button links

40 . What are Bootstrap alerts?

Bootstrap alerts are used to create presume alert messages, which add styles to make the messages more noticeable to the user.

The following contextual classes can be used to create colourful alerts:

  • The .alert-primary class
  • The .alert-secondary class
  • The .alert-success class
  • The .alert-danger class
  • The .alert-warning class
  • The .alert-info class
  • The .alert-light class
  • The .alert-dark class

41 . What are labels?

Labels are used for offering counts, tips, or other things to provide markup on web pages. We use the <label> tag to indicate labels.

42 . What are badges?

Badges are small count and labelling components. We use the .badge class and a contextual class (.badge-*) to create a badge.

43 . How can we make an image responsive?

Add the .img-fluid class to the <img> tag to make an image responsive. It applies the styles, .max-width: 100% and height: auto. So it can match nicely with the parent element.

44 . What is lead?

Lead makes a paragraph stand out. The .lead class is used for this purpose and it enlarges the font and taller increases the line-height as well.

45 . What are the dependencies required to work Bootstrap properly?

 jQuery is the only dependency required to work Bootstrap properly.

46 . What are the different options for adding Bootstrap to your project?

There are several options to add Bootstrap to your project.

They are:

  • Using ready-to-use compiled CSS and JS code.
  • Using source files.
  • Installing via Bootstrap CDN.
  • Installing via package managers such as NPM, Yarn, RubyGems, Composer, etc.

47 . Can we learn Bootstrap without learning CSS?

The simple answer is no. We cannot learn it without learning CSS as it is a CSS framework. Therefore, knowledge of CSS is essential to understand the basic concepts of Bootstrap.

48 . What is flexbox?

Flexbox is a flexible box layout module. You can easily build a flexible layout design using flexbox without using float or positioning.

49 . What do you see as drawbacks?

Bootstrap emphasises standard templates, but standardisation has its limits. Sometimes, projects need greater customization to ensure sites don’t all look the same, and instituting that customization can be time-consuming. Another drawback I’ve occasionally encountered is the template code size. The templates require a lot of code, some of which may prove unnecessary.

50 . What is the Button group and which class is used for the basic button group?

Button groups allow multiple buttons to be stacked together on a single line. You can use this when you want to place items like alignment buttons together.

For the basic button group, .btn-group class is used. Here, you can wrap a series of buttons with class .btn in .btn-group.