JavaScript Programming: Interactive Quizzes for Career and Technical Education

Question 1

Which JavaScript data type is best for storing a collection of key-value pairs?

Accepted Answer

Object

Answer

String

Answer

Array

Answer

Number

Question 2

Which syntax is correct to define a function named 'greetUser' in JavaScript?

Accepted Answer

function greetUser() {}

Answer

fn greetUser() {}

Answer

def greetUser():

Answer

func greetUser() {}

Question 3

In JavaScript, what does the 'this' keyword primarily refer to?

Accepted Answer

The current object

Answer

The last executed expression's value

Answer

A newly created object

Answer

Global variables

Question 4

Which JavaScript data type is designed to hold non-primitive values like arrays and objects?

Accepted Answer

Object

Answer

String

Answer

Number

Answer

Boolean

Question 5

What is the primary purpose of using the 'addEventListener()' method in JavaScript?

Accepted Answer

Adding an event listener to an element

Answer

Removing an event listener from an element

Answer

Dispatching an event

Answer

Creating a new event

Question 6

What is the key distinction between the '==' and '===' comparison operators in JavaScript?

Accepted Answer

'==' compares values, while '===' compares both values and data types

Answer

'==' assigns values, while '===' checks equality

Answer

'==' compares data types, while '===' compares values

Question 7

Which option represents an asynchronous function in JavaScript?

Accepted Answer

async functionName()

Answer

sync functionName()

Answer

await functionName()

Answer

promise functionName()

Question 8

What is the primary function of the 'document.getElementById()' method in JavaScript?

Accepted Answer

Retrieving the HTML element with the specified ID

Answer

Changing the ID of an existing HTML element

Answer

Removing the HTML element with the specified ID

Answer

Creating a new HTML element with the specified ID

Question 9

Which of the following is a valid array method in JavaScript?

Accepted Answer

push

Answer

append

Answer

add

Answer

insert

Question 10

What is the primary purpose of the 'import' statement in JavaScript?

Accepted Answer

Importing modules from separate files

Answer

Creating new modules

Answer

Exporting modules to separate files

Question 11

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

Accepted Answer

Array

Answer

Boolean

Answer

String

Answer

Number

Question 12

The 'this' keyword in JavaScript refers to:

Accepted Answer

Current object

Answer

Function that called it

Answer

Global object

Answer

Previous object

Question 13

Which of the following is a valid declaration of an arrow function?

Accepted Answer

const myFunction = () => {}

Answer

myFunction = () => {}

Answer

var myFunction => {}

Answer

function myFunction => {}

Question 14

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

Accepted Answer

Const cannot be reassigned, let can be reassigned

Answer

Let variables are hoisted, const variables are not hoisted

Answer

Const can only be used in block scope, let cannot

Answer

Const must be initialized, let does not have to be initialized

Question 15

Which array method adds an element to the end of the array?

Accepted Answer

push()

Answer

add()

Answer

append()

Answer

insert()

Question 16

What does the document.getElementById() method do?

Accepted Answer

Returns the element with the specified ID

Answer

Removes an element from the document

Answer

Creates a new element

Answer

Hides an element

Question 17

Which event listener is used to detect a click?

Accepted Answer

addEventListener('click')

Answer

onclick()

Answer

addClick()

Answer

click()

Question 18

What is the purpose of the XMLHttpRequest object?

Accepted Answer

Performs asynchronous HTTP requests

Answer

Creates web pages

Answer

Handles DOM events

Answer

Parses XML data

Question 19

Which built-in method is used for exception handling?

Accepted Answer

try...catch

Answer

error...handle

Answer

catch...throw

Answer

exception...process

Question 20

What is the difference between innerHTML and innerText?

Accepted Answer

innerHTML includes HTML tags, innerText does not

Answer

InnerText is a method, innerHTML is a property

Answer

InnerText is read-only, innerHTML is writable

Answer

InnerText is only for text nodes, innerHTML is for all nodes

Question 21

What is the primary purpose of the 'document.getElementById()' method in JavaScript?

Accepted Answer

To retrieve an HTML element by its unique identifier (ID).

Answer

To create a new HTML element.

Answer

To modify the style of an HTML element.

Answer

To add an event listener to an HTML element.

Question 22

Which of the following represents a valid JavaScript function definition?

Accepted Answer

function functionName(parameters) { code }

Answer

def functionName(parameters): { code }

Answer

func functionName() = { code }

Answer

fn functionName(parameters) := { code }

Question 23

In JavaScript, what does the 'this' keyword primarily refer to?

Accepted Answer

The current object instance.

Answer

The parent object.

Answer

The global object.

Answer

The calling function.

Question 24

What is the primary difference between the '==' and '===' operators in JavaScript?

Accepted Answer

'==' checks for value equality, while '===' checks for both value and type equality.

Answer

'==' is generally faster than '==='.

Answer

'===' can only be used with primitive types.

Question 25

Which JavaScript array method is commonly used to add a new element to the end of an array?

Accepted Answer

push()

Answer

insert()

Answer

add()

Answer

append()

Question 26

What is the main purpose of the 'JSON.parse()' method in JavaScript?

Accepted Answer

To convert a JSON string into a JavaScript object.

Answer

To convert a JavaScript object into a JSON string.

Answer

To validate a JSON string.

Answer

To create a new JSON object.

Question 27

Which of the following is NOT a valid event listener in JavaScript?

Accepted Answer

onclicking

Answer

onmouseover

Answer

onsubmit

Answer

onclick

Question 28

What is the primary purpose of using a 'try...catch' statement in JavaScript?

Accepted Answer

To handle errors and prevent code from terminating abruptly.

Answer

To debug code.

Answer

To create custom exceptions.

Answer

To improve code performance.

Question 29

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

Accepted Answer

It represents the current object context.

Answer

It is not used in JavaScript.

Answer

It represents the previous function context.

Answer

It represents the global object.

Question 30

What is the main purpose of the 'document.getElementById()' method?

Accepted Answer

To select an HTML element by its unique ID attribute.

Answer

To remove an HTML element from the document.

Answer

To create a new HTML element.

Answer

To modify the CSS style of an HTML element.

Question 31

Which event type is used in JavaScript to trigger a function when a user clicks on an HTML element?

Accepted Answer

onclick

Answer

onchange

Answer

onload

Question 32

What is the fundamental difference between declaring a variable using 'var' and 'let' in JavaScript?

Accepted Answer

Var has function scope, while let has block scope.

Answer

There is no difference between var and let.

Answer

Let is used for constant variables, while var is used for non-constant variables.

Answer

Var is used for local variables, while let is used for global variables.

Question 33

What is the primary purpose of the 'addEventListener()' method?

Accepted Answer

To attach an event listener to an HTML element.

Answer

To remove an event listener.

Answer

To modify the event target.

Answer

To trigger an event.

Question 34

Which built-in object in JavaScript is specifically designed for working with arrays?

Accepted Answer

Array

Answer

List

Answer

Collection

Answer

Set

Question 35

What is the purpose of the 'JSON.stringify()' method?

Accepted Answer

To convert a JavaScript object into a JSON string.

Answer

To parse a JSON string.

Answer

To convert a JSON string into a JavaScript object.

Answer

To validate a JSON string.

Question 36

In JavaScript, what reserved keyword is used to declare a variable?

Accepted Answer

var

Answer

define

Answer

set

Question 37

Which of the following syntax is correct to define a function in JavaScript?

Accepted Answer

function functionName() { code }

Answer

define functionName() { code }

Answer

function functionName = { code }

Answer

func functionName() { code }

Question 38

In JavaScript, what is the primary purpose of the 'this' keyword?

Accepted Answer

References the current object context

Answer

Calls a function

Answer

Defines a new object

Answer

Returns the value of a variable

Question 39

Which event listener in JavaScript is used to detect a mouse click on an HTML element?

Accepted Answer

onclick

Answer

onmouseover

Answer

onkeydown

Answer

onchange

Question 40

In JavaScript, what does the 'appendChild' method accomplish?

Accepted Answer

Adds a child node to the end of a parent node

Answer

Replaces a child node with another node

Answer

Removes a child node from its parent

Answer

Inserts a child node before a specified reference node

Question 41

Which of the following is a valid loop structure in JavaScript?

Accepted Answer

for(let i = 0; i < length; i++)

Answer

foreach(let i = 0; i < length)

Answer

if(let i = 0; i < length; i++)

Answer

while(let i = 0; i < length)

Question 42

What is the key difference between the '==' and '===' operators in JavaScript?

Accepted Answer

'==' performs type coercion, while '===' checks for strict equality

Answer

'==' is used for object comparison, '===' for primitive value comparison

Answer

'==' is for numerical comparison, '===' for boolean comparison

Question 43

In JavaScript, what is the purpose of the 'async' keyword?

Accepted Answer

Indicates that a function will perform asynchronous operations

Answer

Defines a synchronous function

Answer

Wraps a synchronous function in an asynchronous context

Question 44

In JavaScript, what does the 'this' keyword refer to?

Accepted Answer

The object that the function is currently associated with.

Answer

The global window object.

Answer

A new variable within the function's scope.

Answer

The function itself.

Question 45

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

Accepted Answer

'let' variables can be reassigned, while 'const' variables cannot.

Answer

'const' variables can be reassigned, while 'let' variables cannot.

Answer

Both 'let' and 'const' variables can be reassigned.

Answer

There is no difference between 'let' and 'const'.

Question 46

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

Accepted Answer

A structured representation of an HTML document that allows JavaScript to interact with it.

Answer

A specific type of JavaScript object.

Answer

A collection of JavaScript functions.

Answer

A storage mechanism for user data.

Question 47

Which of these is NOT a built-in method of the Array object in JavaScript?

Accepted Answer

pushAll()

Answer

pop()

Answer

shift()

Answer

push()

Question 48

What is the primary purpose of the 'addEventListener()' method in JavaScript?

Accepted Answer

To attach a function to be executed when a specific event occurs on a web page element.

Answer

To modify the style of an HTML element.

Answer

To create new elements within the DOM.

Answer

To validate user input before submission.

Question 49

Which of the following is a common use case for JavaScript in web development?

Accepted Answer

Adding interactive elements and dynamic functionality to web pages.

Answer

Managing databases.

Answer

Server-side scripting.

Answer

Controlling the operating system.

Question 50

What is the correct syntax to declare a JavaScript variable?

Accepted Answer

var myVariable;

Answer

variable myVariable;

Answer

v myVariable;

Answer

myVariable = var;

Question 51

What data type is returned by this JavaScript expression: `typeof(5 + "5")`?

Accepted Answer

string

Answer

object

Answer

boolean

Answer

number

Question 52

Which built-in function returns the length of a string in JavaScript?

Accepted Answer

length

Answer

size()

Answer

count()

Answer

getLength()

Question 53

What is the output of this code snippet: `console.log(10 % 3)`?

Accepted Answer

1

Answer

0

Answer

10

Answer

3

Question 54

What is the purpose of the `this` keyword within a JavaScript object?

Accepted Answer

It refers to the current object.

Answer

It defines a new object.

Answer

It refers to the parent object.

Answer

It refers to the global object.

Question 55

Which event handler is triggered when a user clicks on an HTML element?

Accepted Answer

onclick

Answer

onload

Answer

onhover

Question 56

What is the role of the `<script>` tag in an HTML document?

Accepted Answer

Embeds JavaScript code within the HTML document.

Answer

Creates a hyperlink.

Answer

Defines a CSS stylesheet.