35+ Top Bootstrap Interview Questions & Answers [2024 Edition]
1) Explain what Bootstrap is.
Bootstrap is a framework that enables developers to create interactive web applications with minimal effort. Specifically, this framework focuses more on mobile web applications. It uses HTML, CSS, and Javascript.
2) What are the core components of Bootstrap?
The key components of Bootstrap are:
- CSS: Lots of CSS files included.
- Scaffolding: Includes a grid system, link styles, and a background.
- Layout Components: List of layout components.
- JavaScript Plugins: It contains many javascript and jQuery plugins.
- Customize: For your own version of the framework, you can customize your components.
3) What are the different types of layouts in Bootstrap?
Bootstrap provides two types of layouts:
- Fixed Layout: You will use the fixed layout (940 px) option for a standard screen.
- Fluid Layout: If you wish to create an app that covers the entire screen, then you'll use a fluid layout.
4) Explain what class loaders are in Bootstrap.
Classloader is a part of JRE (Java Runtime Environment), which loads Java classes into the Java virtual environment. In addition, class loaders convert named types into their equivalent binary forms.
5) Why should we use Bootstrap to build websites?
Here are a few reasons why we should use Bootstrap to build websites.
- Mobile Support: It provides full support in one single file for mobile devices rather than a separate file. It facilitates responsive design, meaning that you can easily modify CSS based on the device type or even the size of the screen. It reduces the additional efforts of the developer.
- Easy To Learn: Bootstrap is easy to learn provided you have a little knowledge of HTML and CSS.
- Browser Support: It supports all popular web browsers including Opera, Firefox, IE, Safari, etc.
6) What are offset columns in Bootstrap?
For more specialized layouts, offsets are a helpful feature. They can be pushed over to create more spacing. For instance, .col-xs=* classes do not support offset but can be easily duplicated using an empty cell.
7) Explain what the Bootstrap Grid System is.
Bootstrap includes a flexible, mobile-first fluid grid system that appropriately scales up to 12 columns as the device or viewport size increases. In addition to pre-defined classes, it provides powerful mixins for generating a more semantic layout.
8) What function can you use to wrap a page's content?
To wrap page content, you can use .container, and using that; you can also center the content.
9) What are Class Loaders in Bootstrap?
Class loaders in Bootstrap are mechanisms that load and initialize CSS classes dynamically. They are primarily used for JavaScript-based components and plugins, allowing them to load their stylesheets and scripts only when needed, improving page performance.
10) What are Contextual Classes of Tables in Bootstrap?
Contextual classes in Bootstrap are used to style table rows or cells with different background colors to represent different states or types of data. These classes can help highlight specific rows or columns to make the table more informative.
Common Contextual Classes:
- .table-primary: Blue background (indicates important action)
- .table-secondary: Gray background
- .table-success: Green background (indicates success)
- .table-danger: Red background (indicates danger or warning)
- .table-warning: Yellow background
- .table-info: Light blue background (indicates information)
- .table-light: Light gray background
- .table-dark: Dark gray background
Example:
<table class="table">
<thead>
<tr>
<th>#</th>
<th>Column</th>
</tr>
</thead>
<tbody>
<tr class="table-primary">
<td>1</td>
<td>Primary</td>
</tr>
<tr class="table-success">
<td>2</td>
<td>Success</td>
</tr>
<tr class="table-danger">
<td>3</td>
<td>Danger</td>
</tr>
</tbody>
</table>
11) Explain what pagination in Bootstrap is and how they are classified.
Pagination is how Bootstrap handles unordered lists. The following classes are used to handle pagination:
.pagination: You should add this class to your page to get pagination.
- .disabled, .active: Use .disabled for unclickable links and .active to indicate the current page.
- .pagination-Ig, .pagination-sm: Use these classes for different-sized items.
12) What is the use of Jumbotron in Bootstrap?
In Bootstrap, Jumbotron is generally used to enlarge headings' size and add a margin for landing page content. In other words, it highlights certain content, such as a slogan or marketing headline. To use the Jumbotron in Bootstrap:
Create a container <div> with the class of .jumbotron.
13) What Is the Difference Between Bootstrap and Foundation?
These are two of the well-known front-end frameworks. The differences are as follows :
- Popularity: A high percentage of users use Bootstrap. It has a larger community.
- Customization: The foundation is considered more flexible and customizable, allowing developers more control over the design.
- Components: Both offer a very similar set of components, such as buttons, forms, and navigation, with Foundation more touting its mobile-first front and modular structure.
- Grid System: While Bootstrap has a 12-column grid system, Foundation offers both a 12-column and a flexible grid system.
14) What Are Bootstrap Collapsing Elements?
The collapse plugin of Bootstrap enables you to toggle content easily across several elements. The element is normally used to make collapsible sections, accordions, or menus.
Example:
<button class="btn btn-primary" data-toggle="collapse" data-target="#demo">Toggle Collapse</button>
<div id="demo" class="collapse">
Collapsible content here.
</div>
15) What are the Contextual classes of a table in Bootstrap?
Here are the contextual classes of a table in Bootstrap:
.active - Applies the hover color to a particular row or cell
.success - Indicates a successful or positive action
.warning - Identifies a warning that might need attention
.danger - Indicates a dangerous or potentially damaging action
16) In Bootstrap, which two codes are used to display code?
In Bootstrap, you can display code in two simple ways:
<code> tag: This tag is used to display an inline code.
<pre> tag: You can insert this into your code if it includes more than one line or a block element.
17) Give an Example of a Basic Grid Structure in Bootstrap
Bootstrap uses a grid system to create layouts of varying complexity. The grid is made up of rows and columns.
Example:
<div class="container">
<div class="row">
<div class="col-md-4">Column 1</div>
<div class="col-md-4">Column 2</div>
<div class="col-md-4">Column 3</div>
</div>
This example creates a 3-column layout where each column takes up 4 out of 12 available grid spaces (making it one-third of the width).
18) What Are the Two Codes Used for Code Display in Bootstrap?
Bootstrap provides two main ways to display code on your webpage:
1. Inline code: Use the <code> tag to display code within a paragraph.
- Example: <p>For inline code, use the <code><code></code> tag.</p>
2. Block-level code: Use the <pre> tag to display code in a block format.
Example:
<pre><code>
<p>This is a paragraph.</p>
</code></pre>
19) What Is a Progress Bar in Bootstrap?
In its simplest form, a progress bar in Bootstrap is for showing how far along a process is complete. Two classes make up a very simple progress bar: .progress and .progress-bar.
Example:
<div class="progress">
<div class="progress-bar" role="progressbar" style="width: 50%;" aria-valuenow="50" aria-valuemin="0" aria-valuemax="100">50%</div>
</div>
This example creates a progress bar that is 50% complete.
20) Describe the typography and links in Bootstrap.
Bootstrap provides a simple graphical presentation, typography, and link style.
Basic Global display − This sets background-color: #fff; on the element.
Typography − Font-family, font-size, and line-height attributes are used as the typographic basis.
Link styles − The attribute link color sets the global link color and underlines the link only on :hover.
21) Describe the types of lists supported by Bootstrap.
Bootstrap supports three types of lists:
- **Ordered Lists **- An ordered list consists of items in a certain order that are prefixed by numbers.
- Unordered Lists - The unordered list is a list without any particular order. It has traditionally been styled with bullets, but you can remove that style using the class .list-unstyled.
- Definition Lists - Definition lists consist of both the dt> element and the dd> element. The dt> element stands for the definition term, while the dd> element is the definition of the dt> element.
22) What Is Normalize in Bootstrap?
Normalize.css is a CSS file that comes with Bootstrap. It's forcing browsers to display all of the elements more consistently and according to modern standards. It prevents bugs and inconsistencies in different browsers.
23) What Is the Bootstrap Panel?
A panel in Bootstrap 3 is a bordered box with padding around its content. It's used to create boxes that hold content like text, tables, or lists.
Example:
<div class="panel panel-default">
<div class="panel-heading">Panel heading</div>
<div class="panel-body">Panel content</div>
</div>
24) How do you create navigation elements in Bootstrap?
Bootstrap offers several options for styling navigation elements. They all share the same markup and base class .nav. You need to follow these steps to create Tabular Navigation or Tabs.
Create an unordered list with the base class of .nav.
Add class .nav-tabs
25) What do you mean by Bootstrap Well?
Bootstrap wells are simply containers that make content appear to sink. In some cases, it can also create an inset effect on the webpage. Therefore, a developer can create a well and also wrap content using div> and class .well.
26) What are the input groups in Bootstrap?
With input groups, you can easily prepend and append text or buttons to form fields. You can also add common elements to a user's input. For instance, you can add the dollar symbol or the @ sign for a Twitter handle.
A .form-control element can be prepended or appended by using the following syntax:
Wrap it in a div> with the class .input-group
In the next step, place your extra content inside a with class .input-group-addon.
Now place this either before or after the element.
27) What is Bootstrap Breadcrumb?
An excellent way to display hierarchy-based information on a site is through breadcrumbs. When used on a blog, breadcrumbs can display dates of publication, categories, and tags. Breadcrumbs indicate the current link's location in the navigation structure.
In Bootstrap, a breadcrumb is simply an unordered list with the class .breadcrumb. The separator is automatically added by CSS.
28) What is a Bootstrap Container?
Bootstrap containers create a central area on the page where you can place our site content. The bootstrap .container has the advantage of being responsive and will place all our other HTML code.
29) Name some Bootstrap alternatives.
Even though Bootstrap has been one of the most popular front-end frameworks, some other frameworks or Bootstrap alternatives; which are equally good and may suit your requirements better. Here are some alternatives for Bootstrap:
- Foundation by Zurb
- Bulma
- Skeleton
- Pure
- Groundwork
- Cardinal
- Powertocss
- Mueller
- Bootflat
- Materialize
30) Explain the Uses of Carousel Plugin in Bootstrap
A slideshow component for cycling through elements, like a slider: images, or text, is provided by the Bootstrap carousel plugin. This is highly customizable. Options include auto-rotation, captions, controls, and indicators.
Example:
<div id="carouselExample" class="carousel slide" data-ride="carousel">
<div class="carousel-inner">
<div class="carousel-item active">
<img class="d-block w-100" src="image1.jpg" alt="First slide">
</div>
<div class="carousel-item">
<img class="d-block w-100" src="image2.jpg" alt="Second slide">
</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>
31) How Can You Create Nav Elements in Bootstrap?
Bootstrap offers classes to create a variety of navigation bars and menus. Nav elements can be made by using the .nav and .nav-item classes.
Example:
<ul class="nav">
<li class="nav-item">
<a class="nav-link active" href="#">Active</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
</ul>
32) What Are Glyphicons? How to Use Them?
Glyphicons were icon fonts provided in earlier versions of Bootstrap (up to Bootstrap 3). They allowed you to add icons to your project using simple CSS classes.
Example:
<span class="glyphicon glyphicon-search"></span>
Note: In Bootstrap 4 and later, Glyphicons were removed, and developers are encouraged to use other icon libraries like Font Awesome.
33) What Are the Bootstrap Media Objects?
Bootstrap's media object is used to build complex and repetitive components where media (like images or videos) is aligned alongside content (such as text). It’s typically used for comment sections, blog posts, etc.
Example:
<div class="media">
<img src="image.jpg" class="mr-3" alt="...">
<div class="media-body">
<h5 class="mt-0">Media heading</h5>
This is some sample content.
</div>
</div>
34) What Is a Button Group and which class is used for a Basic Button Group?
The button group in Bootstrap is used to group a series of buttons together on a single line. It makes them all look like one piece. The class .btn-group is used to create a basic button group.
Example:
<div class="btn-group" role="group">
<button type="button" class="btn btn-primary">Left</button>
<button type="button" class="btn btn-primary">Middle</button>
<button type="button" class="btn btn-primary">Right</button>
</div>
35) How Do You Create a Modal in Bootstrap?
A modal in Bootstrap is a dialog box/popup window that is displayed on top of the current page. It can be used to show content like forms, alerts, or additional information.
Example:
<!-- Button trigger modal -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">
Launch demo modal
</button>
<!-- Modal -->
<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="exampleModalLabel">Modal title</h5>
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<div class="modal-body">
Modal content goes here.
</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>
36) What Is Bootstrap's Flexbox Grid, and How Is It Different from the Traditional Grid System?
Bootstrap’s Flexbox grid is a more flexible and modern approach to building responsive layouts compared to the traditional float-based grid system used in earlier versions of Bootstrap. The Flexbox grid uses the CSS Flexbox layout model, which allows for more dynamic alignment, distribution, and sizing of grid items.
Differences:
- Alignment: Flexbox allows for vertical and horizontal alignment control within the grid.
- Order: Grid items can be reordered without changing the HTML structure.
- Spacing: Flexbox provides more control over the spacing and distribution of items.
Example:
<div class="container">
<div class="row d-flex align-items-center">
<div class="col-md-6 order-md-2">Content 1</div>
<div class="col-md-6 order-md-1">Content 2</div>
</div>
</div>
This example demonstrates how Flexbox allows for reordering and alignment control within the Bootstrap grid system.
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