Web Technologies

Question 1

What is the purpose of HTML5’s <canvas> element?</canvas>

Answer 1

The <canvas> element provides a way to draw graphics, animations, and other visual content using JavaScript.</canvas>

Question 2

Explain the box model in CSS.

Answer 2

The box model describes how elements are structured in terms of content, padding, border, and margin.

Question 3

How can you include JavaScript in an HTML page?

Answer 3

You can include JavaScript using the

 tag, either inline or by referencing an external file.

Question 4

What is the difference between null and undefined in JavaScript?

Answer 4

null is a deliberate absence of value, while undefined signifies a variable that has been declared but hasn’t been assigned a value.

Question 5

Explain CSS specificity.

Answer 5

CSS specificity determines which styles are applied when there are conflicting rules. It’s based on the combination of selectors used in the rule.

Question 6

What is event delegation in JavaScript?

Answer 6

Event delegation is a technique where you attach an event handler to a parent element and let it handle events on its child elements, reducing memory consumption and improving performance.

Question 7

What is a closure in JavaScript?

Answer 7

A closure is a function that captures variables from its containing lexical scope, allowing those variables to be accessed even after the outer function has finished executing.

Question 8

Explain the concept of hoisting in JavaScript.

Answer 8

Hoisting is the behavior where variable and function declarations are moved to the top of their containing scope during the compilation phase.

Question 9

How does CSS Flexbox work?

Answer 9

Flexbox is a layout model that allows you to design complex layouts with a more efficient and predictable arrangement of elements in a container.

Question 10

What is the purpose of the localStorage and sessionStorage APIs in JavaScript?

Answer 10

These APIs allow you to store key-value pairs in the browser. localStorage stores data with no expiration, while sessionStorage stores data for the duration of a session.

Question 11

What does AJAX stand for?

Answer 11

AJAX stands for “Asynchronous JavaScript and XML,” a set of techniques for making asynchronous requests to a server from a web page.

Question 12

How do you create an AJAX request in JavaScript?

Answer 12

You can use the XMLHttpRequest object or the more modern fetch API to create AJAX requests.

Question 13

What is JSON?

Answer 13

JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write, and easy for machines to parse and generate.

Question 14

How do you parse JSON in JavaScript?

Answer 14

You can use the JSON.parse() method to convert a JSON string into a JavaScript object.

Question 15

What is CORS, and why is it important?

Answer 15

CORS (Cross-Origin Resource Sharing) is a security feature implemented by browsers to prevent unauthorized requests from different origins. It ensures that requests are made only to trusted sources.

Question 16

What is a single-page application (SPA)?

Answer 16

An SPA is a web application that dynamically updates content on a single web page, providing a more fluid and seamless user experience.

Question 17

What is the virtual DOM in React?

Answer 17

The virtual DOM is a lightweight copy of the actual DOM in memory. React uses it to efficiently update the actual DOM by minimizing direct manipulations

Question 18

Explain two-way data binding in Angular.

Answer 18

Two-way data binding automatically synchronizes data between the model and the view, so changes in the view are reflected in the model and vice versa.

Question 19

What is a component in Vue.js?

Answer 19

In Vue.js, a component is a reusable and self-contained unit that encapsulates both the UI and its behavior.

Question 20

What is the purpose of React Router?

Answer 20

React Router is a library that enables client-side routing in a React application, allowing you to create different “pages” within a single-page application.

Question 21

How does Angular handle dependency injection?

Answer 21

Angular has a built-in dependency injection system that allows you to manage and inject dependencies into components, services, and other parts of the application.

Question 22

What is Vuex in Vue.js?

Answer 22

Vuex is a state management library for Vue.js applications, providing a centralized store to manage the application’s state and data.

Question 23

What is JSX in React?

Answer 23

JSX (JavaScript XML) is a syntax extension for JavaScript used with React to describe what the UI should look like.

Question 24

Explain the concept of props in React.

Answer 24

Props (short for properties) are a way to pass data from a parent component to a child component in React.

Question 25

How do you handle forms and user input in Angular?

Answer 25

Angular provides the ngModel directive and reactive forms to handle user input and form validation.

Question 26

What is the purpose of the tag in HTML?

Answer 26

The tag provides metadata about the HTML document, such as character encoding, authorship, and viewport settings.

Question 27

Explain the concept of event propagation in JavaScript.

Answer 27

Event propagation describes the order in which events are processed as they bubble up from the target element through its ancestors or capture down from ancestors to the target.

Question 28

How can you include an external CSS file in an HTML document?

Answer 28

You can link an external CSS file using the element within the section of the HTML document.

Question 29

What is the purpose of the async attribute in a