JavaScript Fundamentals: Master the Basics of Web Development

Question 1

Which of the following is NOT a primitive data type in JavaScript?

Accepted Answer

Symbol

Answer

String

Answer

Number

Answer

Boolean

Question 2

Which JavaScript data structure should you use to efficiently store a collection of key-value pairs?

Accepted Answer

Object

Answer

Array

Answer

Set

Answer

Map

Question 3

Which of the following is NOT a control structure used to control the flow of a JavaScript program?

Accepted Answer

const

Answer

if-else

Answer

while

Answer

try-catch

Question 4

Which JavaScript event listener is used to capture the click event?

Accepted Answer

onclick

Answer

onmouseclick

Answer

onkeydown

Answer

onhover

Question 5

What is the data type of the result of the following JavaScript expression: typeof(10)?

Accepted Answer

Number

Answer

String

Answer

Boolean

Answer

Object

Question 6

Which control structure allows code execution only when a specific condition is true?

Accepted Answer

if statement

Answer

switch statement

Answer

for loop

Answer

while loop

Question 7

What is the primary purpose of the 'break' statement within a JavaScript loop?

Accepted Answer

Terminates the current loop iteration

Answer

Terminates the entire loop

Answer

Skips the current loop iteration

Answer

Pauses the loop execution

Question 8

Which JavaScript method is used to append an element to the end of an array?

Accepted Answer

push()

Answer

pop()

Answer

shift()

Answer

unshift()

Question 9

Which JavaScript function is used to instantiate a new object?

Accepted Answer

new Object()

Answer

create()

Answer

make()

Answer

init()

Question 10

What is the primary function of the 'this' keyword in JavaScript?

Accepted Answer

Refers to the current object

Answer

Refers to the global object

Answer

Refers to the parent object

Answer

Has no special meaning

Question 11

Which JavaScript event is triggered when a user interacts with an HTML element by clicking it?

Accepted Answer

onclick

Answer

onmouseover

Answer

onkeydown

Answer

onload

Question 12

What is the primary purpose of a JavaScript function?

Accepted Answer

To group and reuse code

Answer

To store data

Answer

To create objects

Answer

To control program flow

Question 13

Which data type is used to store true or false values in JavaScript?

Accepted Answer

Boolean

Answer

String

Answer

Number

Answer

Array

Question 14

What is the primary purpose of using the 'this' keyword in JavaScript?

Accepted Answer

To refer to the current object

Answer

To define a new object

Answer

To call a function

Answer

To create a new array

Question 15

What is the key difference between 'const' and 'let' variables in JavaScript?

Accepted Answer

Const variables cannot be reassigned, while let variables can

Answer

Let variables cannot be reassigned, while const variables can

Answer

There is no difference between const and let variables

Answer

Const variables are block-scoped, while let variables are not

Question 16

What is the primary purpose of the Document Object Model (DOM) in JavaScript?

Accepted Answer

To represent the structure of an HTML document

Answer

To define the styling of an HTML document

Answer

To handle user interactions on an HTML document

Answer

To generate reports on an HTML document

Question 17

In JavaScript, what is hoisting? Provide an example to illustrate your answer.

Accepted Answer

Hoisting is a mechanism where variable and function declarations are automatically moved to the top of their scope.

Answer

Hoisting only applies to variable declarations, not function declarations.

Answer

Hoisting significantly enhances the performance of all JavaScript code.

Question 18

**Event Bubbling and Capturing in JavaScript**

Explain how event bubbling and event capturing work in JavaScript. Discuss their significance and practical applications in web development.

Accepted Answer

Event bubbling and capturing are mechanisms that control how events travel through the DOM.

Accepted Answer

Event bubbling allows events to move up from the target element to its ancestors, while event capturing allows events to be handled before reaching the target element.

Answer

Event capturing is not more efficient than event bubbling.

Answer

Event bubbling and capturing apply only to DOM events.

Question 19

Which of the following is a valid data type in JavaScript?

Accepted Answer

String

Answer

Character

Answer

Long

Answer

Double

Question 20

What is the purpose of the 'let' keyword in JavaScript?

Accepted Answer

Declares a variable with limited scope

Answer

Creates an object

Answer

Defines a function

Answer

Assigns a value to a variable

Question 21

What is the purpose of the 'prototype' property in JavaScript?

Accepted Answer

Inherits properties and methods from a parent object

Answer

Returns a value

Answer

Defines a new object

Answer

Calls a method

Question 22

Which of the following is NOT an advantage of using JavaScript in web development?

Accepted Answer

Improved security

Answer

Reduced page load times

Answer

Enhanced accessibility

Answer

Increased interactivity

Question 23

What is the difference between a 'const' and a 'var' variable in JavaScript?

Accepted Answer

Const cannot be reassigned, var can be

Answer

Const has a broader scope than var

Answer

Var cannot be reassigned, const can be

Question 24

Which of the following is the correct syntax to access an element by its ID using JavaScript?

Accepted Answer

document.getElementById('elementId');

Answer

document.getElement('elementId');

Answer

document.querySelector('#elementId');

Answer

getElementById('elementId');