Top 25 Bootstrap Interview Questions & Answers

1) Explain what is Bootstrap?

Bootstrap is a HTML, CSS, and JS framework for building the rich web applications with minimal effort. This framework emphasis more on building mobile web applications.

2) Explain why to choose Bootstrap for building the websites?

There are few reason why we choose Bootstrap for building websites

• Mobile Support: For mobile devices it provides full support in one single file rather than in separate file. It supports the responsive design including adjusting the CSS based on the different types of device, size of the screen etc. It reduces extra effort for developers.
• Easy to learn: Writing application in bootstrap is easy if you know CSS and HTML
• Browser Support: It supports all the popular browsers like Firefox, Opera, Safari, IE etc.

3) What are the key components of Bootstrap?

The key components of Bootstrap are

• CSS : It comes with plenty of CSS files
• Scaffolding : It provides a basic structure with Grid system , link styles and background
• Layout Components : List of layout components
• JavaScript Plugins: It contains many jQuery and JavaScript plugins
• Customize: To get your own version of framework you can customize your components

4) Explain what are class loaders in Bootstrap?

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

5) What are the types of layout available in Bootstrap?

In Bootstrap there are two types of Layout available

• Fluid Layout: Fluid layout is used when you want to create a app that is 100% wide and use up all the width of the screen
• Fixed Layout: For a standard screen you will use fixed layout (940 px) option

6) Explain what is Bootstrap Grid System?

For creating page layout through a series of rows and columns that house your content Bootstrap Grid Sytem is used.

7) What are offset columns in Bootstrap?

For more specialized layouts offsets are a useful feature. For more spacing they can be used by pushing column over.

For example, .col-xs=* classes do not support offset but they are easily replicated using an empty cell

8) What is column ordering in Bootstrap?

Column ordering is one of the feature available in bootstrap and you can easily write columns in an order and show them in another one. With .col-md-push-* and .col-md-pull-*

the order of the column can be easily changed.

9) What function you can use to wrap a page content?

To wrap a page content you can use .container and using that you can also center the content.

10) Explain what pagination in bootstrap is and how they are classified?

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

• .pagination: To get pagination on your page you have to add this class
• .disabled, .active: Customize 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

11) What is the use of Jumbotron in Bootstrap?

In bootstrap, Jumbotron is generally used for content that you want to highlight like some slogan or marketing headline etc. in other words it is used to enlarge the size of the headings and to add a margin for landing page content

To use the Jumbotron in Bootstrap

• Create a container <div> with the class of .jumbotron

12) What is the difference between Bootstrap and Foundation?

Bootstrap	Foundation
– Bootstrap offers unlimited number of UI elements	– In Foundation UI element options are very limited in numbers
– Bootstraps uses pixels	– Foundation use REMs
– Bootstrap encourages to design for both desktop and mobile.	– Foundation encourages to design mobile first
– Bootstrap support LESS as its preprocessor	– Foundation support Sass and Compass as its preprocessor

13) In Bootstrap what are the two ways you can display the code?

In bootstrap you can display code in two ways

• <code> tag : If you are going to display code inline, you should use <code> tag
• <pre> tag: If you want to display the code as a standalone block element or it has multiple lines then you should use <pre> tag

14) 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

15) Explain what is Modal plugin used for in Bootstrap?

A modal is a child window that is layered over its parent window. Using a custom Jquery Plugin, Bootstrap Modal are created. To enrich user experience and to add functionality to users, modal windows are created with the help of Modal plugin.

16) Explain what is Bootstrap Container?

Bootstrap container is a class which is useful and creates a centred area within the page where our site content can be put within. The advantage of the bootstrap .container is that it is responsive and will place all our other HTML code.

17) Explain what is Bootstrap collapsing elements?

Bootstrap collapsing elements enables you to collapse any particular element without writing any JavaScript code or the accordion markup. In Bootstrap to apply collapsing elements you have to add data-toggle= “collapse” to the controller element along with a data-target or href to automatically assign control of a collapsible element. Likewise, you can use .collapse (options), .collapse (‘show’) or .collapse (‘hide’)

18) Explain what is list group in Bootstrap and what is the use of it?

List groups are components to display both simple and complex element with custom content

For example, a simple list group is created using class .list-group to address the list, and class .list-group-item to address individual item.

19) How you can add badge to list group in Bootstrap?

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

20) Explain what media object in Bootstrap is and what are their types?

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

They are of two types

• .media
• .media-list

21) Explain what is Bootstrap well?

Bootstrap well is a container <div> that makes the content to appear sunken or an inset effect on the page. In order to create a well, wrap the content that you would like to appear in the well with a <div> containing the class of .well.

22) Explain how you can create Nav elements in Bootstrap?

Bootstrap offers various options for styling navigation elements all of them use the same markup and base class .nav.

To create Tabular Navigation or Tabs

• Start with a basic unordered list with the base class of .nav
• Then add class .nav-tabs

23) Explain what is the use of Bootstrap Carousel plugin?

The Carousel plugin is used to add a slider to your site. It is useful in condition where you want to display huge amount of contents within a small space on the web pages. Some of the standard carousel includes

• .carousel (options)
• .carousel (‘cycle’)
• .carousel (‘pause’)
• .carousel (‘number’)
• .carousel (‘prev’)
• .carousel (‘next’)