JavaScript Functions and Events: Interactive Learning Quizzes

Question 1

Which of the following is NOT a valid syntax to define a function in JavaScript?

Accepted Answer

const function myFunction() {}

Answer

function myFunction() {}

Answer

const myFunction = function() {}

Answer

var myFunction = function() {}

Question 2

Which event listener is used to handle the click event on an HTML element?

Accepted Answer

onclick

Answer

onmouseover

Answer

onfocus

Answer

onchange

Question 3

What is the purpose of the 'this' keyword within a JavaScript method?

Accepted Answer

It refers to the current object the method belongs to

Answer

It refers to the global object

Answer

It is a placeholder for the object to be passed as an argument

Answer

It has no special meaning

Question 4

Which of the following is NOT a reserved keyword in JavaScript?

Accepted Answer

interface

Answer

var

Answer

let

Answer

const

Question 5

Which syntax correctly defines a function named 'greetUser' in JavaScript?

Accepted Answer

function greetUser() {}

Answer

var greetUser = function() {}

Answer

function greetUser = function() {}

Answer

var function greetUser() {}

Question 6

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

Accepted Answer

Register an event listener for a specific event on an element

Answer

Remove an event listener from an element

Answer

Trigger an event on an element

Answer

Check if an event listener exists for an element

Question 7

Which built-in JavaScript event occurs when the mouse hovers over an element?

Accepted Answer

mouseover

Answer

hover

Answer

mouseenter

Answer

mousedrag

Question 8

What is the function of the 'getElementById' method in JavaScript?

Accepted Answer

Retrieve an element by its ID

Answer

Create a new element with the specified ID

Answer

Remove an element from the DOM

Answer

Modify the attributes of an element

Question 9

How do the 'innerHTML' and 'innerText' properties differ in JavaScript?

Accepted Answer

innerHTML includes HTML tags while innerText does not

Answer

innerText includes HTML tags while innerHTML does not

Answer

They are identical and perform the same function

Answer

innerHTML pertains to styling while innerText pertains to content modification

Question 10

What does DOM stand for in JavaScript?

Accepted Answer

Document Object Model

Answer

Data Object Model

Answer

Document Information Model

Answer

Data Information Model

Question 11

Which method is used to change the HTML content of an element?

Accepted Answer

innerHTML

Answer

outerHTML

Answer

textContent

Answer

innerText

Question 12

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

Accepted Answer

To stop the default behavior of an event

Answer

To cancel an event

Answer

To delay an event

Answer

To reverse an event

Question 13

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

Accepted Answer

To attach an event listener to an element

Answer

To remove an event listener from an element

Answer

To trigger an event on an element

Answer

To handle multiple events on an element

Question 14

Which JavaScript keyword is used to define a new function?

Accepted Answer

function

Answer

declare

Answer

define

Answer

create

Question 15

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

Accepted Answer

To add an event listener to an HTML element

Answer

To remove an event listener from an HTML element

Answer

To trigger an event on an HTML element

Answer

To check if an event has occurred on an HTML element

Question 16

Which JavaScript property represents the HTML element that triggered an event?

Accepted Answer

target

Answer

source

Answer

element

Answer

origin

Question 17

What is the key difference between a function parameter and a function argument in JavaScript?

Accepted Answer

Parameters are defined in the function declaration, while arguments are passed when the function is invoked

Answer

Arguments are defined in the function declaration, while parameters are passed when the function is invoked

Answer

Parameters and arguments are interchangeable terms

Answer

There is no difference

Question 18

Which JavaScript operator is used for strict equality comparison?

Accepted Answer

===

Answer

==

Answer

!=

Answer

!=

Question 19

What is the primary function of the 'preventDefault' method in JavaScript event handling?

Accepted Answer

To prevent the default action of an event

Answer

To trigger an event

Answer

To stop the propagation of an event

Answer

To cancel an event

Question 20

In JavaScript, the correct syntax to define a function is:

Accepted Answer

function myFunction(params) { ... }

Answer

myFunction = function(params) { ... }

Answer

myFunction { ... }

Answer

function myFunction := (params) { ... }

Question 21

To obtain an element's inner HTML content, which method is used?

Accepted Answer

innerHTML

Answer

querySelector()

Answer

getElementByTagName()

Answer

getElementById()

Question 22

To correctly declare a JavaScript function called 'greetUser()' that takes a 'name' parameter, which statement should be used?

Accepted Answer

function greetUser(name) {}

Answer

function greetUser => name {}

Answer

function name => greetUser()

Answer

function := greetUser(name) {}

Question 23

The 'document.querySelector()' method in JavaScript is primarily designed for:

Accepted Answer

Selecting the first matching element in the DOM

Answer

Retrieving all matching elements in the DOM

Answer

Creating new elements in the DOM

Answer

Removing elements from the DOM

Question 24

Which JavaScript method converts a string to lowercase representation?

Accepted Answer

toLowerCase()

Answer

toUpper()

Answer

toLower()

Answer

toUpperCase()

Question 25

Which JavaScript array method removes and returns the last element of an array?

Accepted Answer

pop()

Answer

unshift()

Answer

push()

Answer

shift()

Question 26

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

Accepted Answer

References the current object in its context

Answer

References the global object

Answer

References the window object

Answer

References the document object

Question 27

What is the primary function of the 'call' and 'apply' methods in JavaScript?

Accepted Answer

Pass arguments to a function

Answer

Create a new function

Answer

Add an event listener to an element

Answer

Modify the DOM directly

Question 28

What type of event occurs when a user releases a key on the keyboard?

Accepted Answer

keyup

Answer

keypress

Answer

input

Answer

keydown

Question 29

Which method is used to add an event listener to an element?

Accepted Answer

addEventListener

Answer

listenForEvent

Answer

handleEvent

Answer

addEvent

Question 30

What is the purpose of the `this` keyword in JavaScript?

Accepted Answer

It refers to the current object context.

Answer

It is used to access global variables.

Answer

It represents the parent object of the current object.

Answer

It stores a reference to the window object.

Question 31

What is the expected output of the following code snippet: `const a = 5; a += 10; console.log(a);`?

Accepted Answer

15

Answer

5

Answer

NaN

Answer

10

Question 32

**Let** and **Const** are two JavaScript keywords used to declare variables. What is the **key difference** between them?

Accepted Answer

**Const** is used for declaring **constants** that cannot be reassigned, while **let** is used for declaring **variables** that can be reassigned.

Answer

**Let** is used for declaring constants that cannot be reassigned, while **const** is used for declaring variables that can be reassigned.

Question 33

Which of the following is a **valid** regular expression to match a **valid email address**?

Accepted Answer

^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$

Answer

^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+$

Question 34

In JavaScript event handling, what is the primary purpose of the **`preventDefault`** method?

Accepted Answer

To prevent the **default action** associated with the event from occurring.

Answer

To stop the event from bubbling up the DOM tree.

Answer

To cancel the event listener.

Question 35

What is the **proper syntax** for defining a JavaScript function?

Accepted Answer

**function functionName() {}**

Answer

**func functionName {}**

Answer

**def functionName {}**

Answer

**fun functionName() {}**

Question 36

In JavaScript event handling, what does the **`this`** keyword refer to?

Accepted Answer

The **current DOM element** that triggered the event.

Answer

Stores the value of **`self`**

Answer

Defines a new variable with the event object

Question 37

Which DOM method is used to **attach an event listener** to an element?

Accepted Answer

.**addEventListener**()

Answer

.**addEvent**()

Answer

.**getEvent**()

Answer

.**handleEvent**()

Question 38

What is the **key difference** between using **`onclick`** and **`.addEventListener`** for event handling in JavaScript?

Accepted Answer

**`.addEventListener`** allows attaching **multiple** event handlers, while **`onclick`** allows only **one**.

Answer

**`onclick`** is more efficient

Answer

**`addEventListener`** is only supported in modern browsers

Question 39

Which of the following is the **correct** way to **call** a JavaScript function?

Accepted Answer

**functionName()**

Answer

execute functionName

Answer

call functionName

Question 40

When using JavaScript's **`preventDefault()`** method in event handling, what is its **main purpose**?

Accepted Answer

To **prevent** the **default action** of the event.

Answer

To stop the propagation of the event

Answer

To trigger the default action of the event

Answer

To add a new event to the element

Question 41

Which of the following is the **correct** way to **pass an argument** to a JavaScript function?

Accepted Answer

**functionName(argument)**

Answer

functionName argument

Answer

argument functionName

Answer

invoke functionName with argument

Question 42

In a JavaScript function, what is the primary purpose of the 'return' statement?

Accepted Answer

To return a value or result from the function

Answer

To define a new variable

Answer

To call another function

Answer

To end the execution of the function

Question 43

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

Accepted Answer

click

Answer

onClick

Answer

handleClick

Answer

clickEvent

Question 44

Within JavaScript event objects, what does the 'target' property represent?

Accepted Answer

The DOM element that initiated the event

Answer

The timestamp of the event

Answer

The type of event that occurred

Question 45

In a JavaScript event handler, what is the purpose of the 'this' keyword?

Accepted Answer

To refer to the element that triggered the event

Answer

To store event data

Answer

To access global variables

Answer

To define a new variable

Question 46

When a user clicks a button, which event is triggered?

Accepted Answer

onclick

Answer

onload

Answer

onchange

Answer

onmouseover

Question 47

What is the Document Object Model (DOM)?

Accepted Answer

A representation of the HTML document in the computer's memory

Answer

A library for styling web pages

Answer

A programming language for web development

Answer

A tool for debugging JavaScript code

Question 48

Describe the primary difference between a 'for' loop and a 'while' loop in JavaScript.

Accepted Answer

A 'for' loop iterates a specific number of times, whereas a 'while' loop iterates until a condition is no longer met.

Answer

A 'for' loop is always faster than a 'while' loop.

Question 49

In JavaScript, what is the purpose of a semicolon at the end of a statement?

Accepted Answer

To end the statement and minimize potential errors

Answer

To improve the readability of the code

Answer

To execute the next statement immediately

Answer

To declare a new variable

Question 50

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

Accepted Answer

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

Answer

'==' is faster than '==='

Answer

'===' is more versatile than '=='