Top 25+ Bootstrap Interview Questions and Answers

Bootstrap is a front-end framework that provides a set of tools and components for creating responsive, mobile-first, and user-friendly websites. It is based on HTML, CSS, and JavaScript and uses a 12-column grid system to organise the layout of the web pages.

It also offers pre-designed components such as buttons, forms, navigation, alerts, modals, and more that can be easily integrated and customised in your web projects. Bootstrap is compatible with all modern browsers and devices and has a large and active community of developers and designers.

Bootstrap is preferred for website development for several reasons, such as:

a) It saves time and effort by providing ready-made components and utilities that can be used out of the box or with minimal customisation

b) It ensures consistency and quality by following the best practices and standards of web design and development

c) It enhances the user experience by making the websites responsive, adaptive, and accessible across different screen sizes and devices

d) It facilitates collaboration and communication by using a common language and framework among developers and designers

e) It supports customisation and extensibility by allowing you to modify the default settings, variables, and themes of Bootstrap or create your own components and plugins

The key components of Bootstrap are:

a) Grid system: A 12-column layout system that helps you create responsive and flexible web pages

b) Components: A set of reusable and modular UI elements that include buttons, forms, navigation, alerts, modals, and more

c) Utilities: A set of helper classes that enable you to customise the appearance and behavior of your elements, such as margins, paddings, colors, borders, display, position, and more

d) JavaScript plugins: A set of interactive and dynamic features that add functionality and interactivity to your components, such as dropdowns, carousels, tooltips, popovers, and more

a) Responsive design: Bootstrap uses a grid system and media queries to make the websites adapt to different screen sizes and devices

b) Mobile-first approach: Bootstrap prioritises the mobile devices and optimises the websites for smaller screens and touch inputs

c) Cross-browser compatibility: Bootstrap ensures that the websites work well on all modern browsers and platforms, such as Chrome, Firefox, Safari, Edge, and more

d) Customisation and theming: Bootstrap allows you to customise and theme the framework according to your preferences and needs, by changing the default variables, settings, and themes or creating your own

e) Accessibility and performance: Bootstrap follows the web accessibility guidelines and standards and uses semantic and valid HTML, CSS, and JavaScript to improve the performance and usability of the websites

Class loaders are utility classes that provide visual feedback to the users while loading or processing data. They are often used to indicate the progress or status of an operation, such as loading, saving, uploading, downloading, etc. Bootstrap provides four types of class loaders, namely:

a) Spinner

b) Grow spinner

c) Progress bar

d) Progress spinner

Contextual classes of table are classes that add colour and meaning to the table rows or cells based on the data they represent. They are often used to highlight or emphasise certain rows or cells, such as success, danger, warning, info, etc. Bootstrap provides six contextual classes of table, namely:

a) .table-active: Applies a light grey background colour to the table row or cell

b) .table-primary: Applies a blue background colour to the table row or cell

c) .table-secondary: Applies a grey background colour to the table row or cell

d) .table-success: Applies a green background colour to the table row or cell

e) .table-danger: Applies a red background colour to the table row or cell

f) .table-warning: Applies a yellow background colour to the table row or cell

g) .table-info: Applies a light blue background colour to the table row or cell

h) .table-light: Applies a white background colour to the table row or cell

i) .table-dark: Applies a black background colour to the table row or cell

Bootstrap provides three types of layouts for creating responsive and flexible web pages, namely:

a) Fixed layout: A layout with a fixed width that does not change according to the screen size. It is suitable for websites that have a simple and minimal design and do not require much responsiveness. It can be achieved by us

b) Fluid layout: A layout that has a full width and adapts to the screen size. It is suitable for websites with complex and dynamic designs and requires high responsiveness. It can be achieved using the class .container-fluid on the parent element of the grid system.

c) Responsive layout: A layout that combines the features of both fixed and fluid layouts and adjusts the width and breakpoints of the grid system according to the screen size. It is suitable for websites that have a varied and diverse design and require a moderate level of responsiveness.

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Column ordering is a feature of Bootstrap that allows you to change the order or position of the grid columns without changing the HTML markup. It is useful for creating different layouts and designs for different screen sizes and devices. It can be achieved by using the classes .order-, .order-sm-, .order-md-, .order-lg-, and .order-xl-* on the grid columns, where * is a number from 1 to 12 that represents the order of the column.

You can use the function .container(. to wrap a page content in Bootstrap. This function creates a container element that has a fixed or fluid width and centres the content horizontally. It also adds a horizontal padding to the content to prevent it from touching the edges of the screen. The function .container(. can take one argument, which is either ‘fixed’ or ‘fluid’, to specify the type of the container. If no argument is given, the default type is ‘fixed’.

Pagination in Bootstrap is a component that allows you to divide a large amount of data or content into multiple pages and provide navigation links to access them. It is often used to improve the user experience and performance of websites with much data or content, such as blogs, e-commerce, search results, etc.

Jumbotron is a component that creates a large and prominent box that showcases a key message or call to action on a web page. It is often used to highlight a website's or section's main purpose or feature. It can be created by using the class .jumbotron on a div element and adding a heading and a paragraph inside it. It can also be placed inside a container element to make it responsive and cantered.

Bootstrap and Foundation are both popular and widely used front-end frameworks that provide a set of tools and components for creating responsive and modern websites. However, they have some differences, such as:

a) Design and style: Bootstrap has a more distinctive and recognisable design and style, with predefined colours, fonts, and themes. Foundation has a more minimal and neutral design and style, with more flexibility and customisation options.

b) Components and plugins: Bootstrap has more components and plugins than Foundation, such as cards, badges, spinners, progress bars, etc. Foundation has fewer components and plugins, but some unique ones, such as orbit, reveal, abide, etc.

c) Grid system: Bootstrap uses a 12-column grid system that can be nested and reordered. Foundation uses a flexible grid system that can have any number of columns and can be nested, reordered, and offset.

d) Mobile-first approach: Bootstrap follows a mobile-first approach, which means that the websites are designed and optimised for mobile devices first and then scaled up for larger screens. Foundation follows a desktop-first approach, which means that the websites are designed and optimised for desktop devices first and then scaled down for smaller screens.

In Bootstrap, you can display the code in two ways, namely:

a) Inline code: A way to display the code within a paragraph or a sentence. It can be achieved by using the tag or the class .code on a span element. It applies a monospace font and a grey background colour to the code.

b) Code block: A way to display the code as a separate block of text. It can be achieved by using the

tag or the class .pre on a div element. It applies a monospace font and a grey background colour to the code and preserves the formatting and indentation of the code.

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The steps for creating basic or vertical forms in Bootstrap are:

Modal plugin is a JavaScript plugin that creates a modal window or a dialog box that overlays the current web page and displays some content or information. It is often used to show a confirmation message, a form, an image, a video, or any other content that requires user attention or interaction.

It can be created by using the class .modal on a div element and adding the required attributes and elements, such as

a) .modal-dialog

b) .modal-content

c) .modal-header

d).modal-body

e) .modal-footer

It can also be triggered by using the data-toggle and data-target attributes on a button or a link element.

Bootstrap Container is a parent element that wraps and centres the content of a web page horizontally. It also adds a horizontal padding to the content to prevent it from touching the edges of the screen.

It can be created by using the class .container or .container-fluid on a div element. The class .container creates a fixed-width container that adapts to the screen size and breakpoints. The class .container-fluid creates a full-width container that spans the entire width of the screen.

Bootstrap collapsing elements are elements that can be toggled to show or hide their content by clicking on a button or a link. They are often used to create accordions, collapsible panels, dropdown menus, navigation bars, and more. They can be created by using the class .collapse on the element that contains the content and adding the data-toggle and data-target attributes on the element that triggers the collapse. They can also be controlled by using the JavaScript methods .collapse(., .show(., .hide(., and .toggle(..

List group is a component that creates a list of items that can be styled and customised in various ways. It is often used to display a simple or complex list of information, such as contacts, comments, links, menus, etc.

It can be created by using the class .list-group on a

• or
  1. element and adding the class .list-group-item on each
  2. element. It can also be enhanced by adding the classes .list-group-flush, .list-group-horizontal, .list-group-numbered, .list-group-action, and .list-group-action-* to change the appearance and behaviour of the list group.

      

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You can add badge to list group in Bootstrap by using the class .badge on a element and placing it inside the .list-group-item element. You can also add the classes .badge-pill, .badge-primary, .badge-secondary, .badge-success, .badge-danger, .badge-warning, .badge-info, .badge-light, and .badge-dark to change the shape and colour of the badge. You can also add the class .align-top, .align-middle, or .align-bottom to change the vertical alignment of the badge.

Media object in Bootstrap is a component that creates a layout that consists of an image or a video on the left or right side and some content on the opposite side. It is often used to display a list of comments, posts, tweets, etc.

It can be created by using the class .media on a div element and adding the classes .media-body and .media-object on the elements that contain the content and the image or video respectively. It can also be nested and aligned by using the classes .media-list, .media-left, .media-right, and .media-middle.

Bootstrap well is a component that creates a box that has a border and a light grey background color. It is often used to highlight or separate some content or information on a web page. It can be created by using the class .well on a div element. It can also be resized by using the classes .well-lg and .well-sm.

You can create Nav elements in Bootstrap by using the class .nav on a

• element and adding the class .nav-item on each
• element. You can also add the class .nav-link on each element to create a link for each nav item. You can also add the classes .active, .disabled, and .dropdown to change the state and behaviour of the nav items. You can also add the classes .nav-tabs, .nav-pills, .nav-fill, and .nav-justified to change the style and layout of the nav elements.

Bootstrap Carousel plugin is a JavaScript plugin that creates a slideshow of images or videos that can be controlled by the user or by the script. It is often used to showcase the features or products of a website or a section.

It can be created by using the class .carousel on a div element and adding the required attributes and elements, such as .carousel-inner, .carousel-item, .carousel-control-prev, .carousel-control-next, .carousel-indicators, and .carousel-caption. It can also be customised by using the data-ride, data-interval, data-pause, and data-wrap attributes on the .carousel element.

Bootstrap well is the same as the answer for question 21. It is a component that creates a box that has a border and a light grey background colour. It is often used to highlight or separate some content or information on a web page. It can be created by using the class .well on a div element. It can also be resized by using the classes .well-lg and .well-sm.

A Bootstrap container is a fundamental layout element that wraps and confines the content within a responsive grid system. Acting as a foundational building block, it ensures consistent padding and margins, facilitating a structured and adaptable design. The container class is integral to Bootstrap's grid system, allowing developers to create responsive and visually cohesive web layouts across various devices. With its flexibility, the Bootstrap container is a key component in crafting modern and user-friendly interfaces in web development.